Abstract
The hybrid structures of graphene with semiconductor materials based on photogating effect have attracted extensive interest in recent years due to the ultrahigh responsivity. However, the responsivity (or gain) was increased at the expense of response time. In this paper, we devise a mechanism which can obtain an enhanced responsivity and fast response time simultaneously by manipulating the photogating effect (MPE). This concept is demonstrated by using a graphene/silicon-on-insulator (GSOI) hybrid structure. An ultrahigh responsivity of more than 107 A/W and a fast response time of 90 µs were obtained. The specific detectivity D* was measured to be 1.46 ⨯ 1013 Jones at a wavelength of 532 nm. The Silvaco TCAD modeling was carried out to explain the manipulation effect, which was further verified by the GSOI devices with different doping levels of graphene in the experiment. The proposed mechanism provides excellent guidance for modulating carrier distribution and transport, representing a new route to improve the performance of graphene/semiconductor hybrid photodetectors.
1 Introduction
Graphene is considered as a promising material for photodetectors because of its unique properties of extremely high carrier mobility and ultra-broadband photoresponse [1], [2], [3], [4], [5], [6]. However, the low optical absorption and short carrier lifetime usually lead to a low photoelectric response for monolayer graphene devices [7]. Optical resonators [8], [9], metal gratings, and plasmonic nanostructures can promote the interaction between graphene and light [10], [11], [12], which improves the light responsivity to a certain degree. But, the problem of low responsivity cannot be thoroughly solved by such optical manipulation methods. Thus, the photogating mechanism [13] based on hybrid structures of graphene with other semiconductor materials, such as quantum dots [14], [15], perovskites [16], carbon nanotubes [17], and MoS2 [18], has been shown to efficiently improve the responsivity. However, the responsivity was increased at the expense of response time, and the overall performance is still restricted by the photogating effect.
Effective control of electron coupling at the heterojunction interface has become a critical issue to improve the photogating effect [18], [19], [20], [21], [22], [23], [24], [25]. One method is to introduce an electric field at the interface to control the Schottky barrier directly. However, slow response speeds are still caused by the long-lived trapping of charges, which are often manifested as hysteresis in gate-voltage sweeps [18], [19], [20], [21], [22], as observed in the Graphene–silicon photodetector [23] and graphene–CQD photodiode [24]. Therefore, it is imperative to develop a new mechanism and method to improve the sensitivity and response speed of photodetectors simultaneously.
In this work, a new mechanism called manipulating the photogating effect (MPE) is proposed, and which is validated by using the graphene/silicon-on-insulator (GSOI) hybrid photodetector in photoconductive mode. By the MPE mechanism, the enhanced built-in potential of heterojunction and carrier concentration gradient in silicon can be controllably manipulated to improve the sensitivity and response speed of the device simultaneously. The experimental results demonstrate that a high responsivity can be obtained without the sacrifice of responding bandwidth for the first time, namely, it does not slow down the photoresponse speed caused by the long-lived trapping of charges [18], [23]. The responsivity of the GSOI device by MPE can reach 107 A/W, which is 10 times higher than that without vertical voltage, and the response time can be shortened from 1000 μs to 90 µs. A detectivity (D*) of 1.46 ⨯ 1013 Jones was measured, which is superior to the reported silicon/graphene hybrid photodetectors [1], [23], [25], [26], [27], [28], [29], [30]. Besides, we analyzed the carrier distribution and coupling behavior of the graphene-silicon interface by using the Silvaco TCAD software. A model between the manipulation law of device and vertical voltage was established, which is consistent well with the experimental results. These results confirm the vital role of manipulation effects in optoelectronic conversion and pave the way to explore novel fast and high-responsivity photodetectors.
2 Results and discussion
The GSOI heterostructure photodetector is schematically shown in Figure 1A. The SOI wafers with lightly doped p-type silicon layers on top of a buried silicon oxide film were employed. A monolayer graphene as the conducting channel was transferred onto the top-silicon surface by wet transfer method. Au films were deposited onto the surface of graphene to form an Ohmic contact (see Figure S1 of Supplementary Material) using electron beam evaporation. Both the source and drain electrodes were patterned via a lift-off process. Subsequently, the graphene film was patterned into strips by bilayer photolithography and dry etching process (see details in the Methods section). Figure 1B shows the SEM image of the GSOI device, in which the surface morphology of graphene is extremely smooth to ensure excellent contact with the underlying silicon.
(a) Schematic view of the graphene/silicon-on-insulator (GSOI) heterojunction device in photoconductive mode. (b) SEM image of the GSOI device. The monolayer graphene strip (10 × 10 µm) directly attaches to the top-silicon, as shown in the dotted wireframe. (c) Energy band diagrams of the photodetector under positive vertical voltage. (d) Energy band diagrams of the photodetector under negative vertical voltage. Electrons and holes are denoted by blue and yellow circles, respectively.
When light illuminates on the GSOI device, photogenerated electron-hole pairs are generated in the top-silicon and separated under the built-in potential at the junction of graphene and silicon. Graphene behaves as a fast transfer channel of photogenerated charge herein. In MPE mechanism, when a vertical voltage is applied, the accumulation of induced charge on the two sides of silicon oxide will be manipulated, which will change the carrier concentration in the top-silicon [31]. The excess electrons or holes will inject into graphene, resulting in a change of sheet current. The energy band diagrams of the photodetector under the positive and negative vertical voltage conditions are as shown in Figure 1C and D respectively. Because the top-silicon is extremely thin (220 nm), the concentration and distribution gradient of carriers in top-silicon can be readily influenced by the induced charges. The remarkable increment of holes or electrons in top-silicon will break the dynamic equilibrium of the heterojunction between the graphene and top-silicon, and greatly alters the Fermi level of graphene. It should be noted that the carrier concentration of graphene is about 1012 cm−2, which is far less than the p-doped silicon (1017 cm−2). Thus, the variation of graphene’s Fermi level is more obvious than silicon that can be ignored [27]. By adjusting the concentration, an increased built-in potential is formed between graphene and top-silicon to improve the separation efficiency of photocarriers. Moreover, the concentration gradient formed by the accumulation of carriers will speed up the diffusion of photogenerated carriers to the heterojunction region. Therefore, both high gain and fast photoresponse can be achieved through the manipulation effect in GSOI heterostructure.
The effects of MPE on lightly p-doped graphene devices were firstly investigated. The bipolarity of such device was exploited [32], [33], and the doping level of graphene was obtained by measuring the transfer curves, as plotted in Figure S2. The relationship of Ids with Vds is shown in Figure 2A, which demonstrates that Vg has a crucial influence on the magnitude and slope of Ids. When Vg is negative, the Ids are relatively large. In contrast, the Ids would become relatively small as Vg turns positive.
(a) Relationship of source-drain current (Ids) with source-drain voltage (Vds) under different Vg in the dark state. The inset shows the curve details of Vg = 10, 30, and 60 V. (b) Ids as a function of the vertical voltage under different optical powers. The inset shows the curve details around the “inflection point”. (c) Time-dependent photoresponse to the periodic chopping of the light source when Vg = 0, 30, and 60 V. The yellow and white region corresponds to the light-adding and non-light period, respectively. The illumination power is 920 µw. (d) Responsivity and photocurrent versus different optical power when Vg = 30 V.
The GSOI photodetector was illuminated by a visible laser with 532 nm wavelength accompanied with one optical attenuator, to obtain an adjustable input power. Figure 2B shows the variation of Ids with Vg under different light powers. As Vg varies from −60 to 60 V, all Ids curves exhibit a similar trend, namely, the photocurrent dramatically decreases from a high value to an “inflection point” around 0 V, and gradually rises afterward as Vg further increases. Such phenomenon can be attributed to the carrier manipulation in the graphene. For the lightly p-doped graphene, the holes play a major role in the conductance of graphene when Vg = 0 V. When a negative Vg is applied, a number of holes accumulate in the top-silicon and inject into the adjacent graphene, thus the Ids produces a noticeable increment. When Vg turns positive and is still smaller than the voltage of the “inflection point”, the Ids declines, because the graphene becomes doped by electrons instead of holes. As the further increase of Vg, abundant electrons will be injected into graphene, leading to a drastic increase of Ids. In short, the "inflection point" corresponds to the transition of the type of majority carrier in graphene. Note that the “inflection point” makes a tiny shift with the increasing of optical power, as shown in the inset of Figure 2B. Because more carriers can be photogenerated and more electrons can be injected into graphene as the optical power increases, therefore, a relatively smaller Vg is required to induce the “inflection point”.
Figure 2C shows the photocurrent response under different Vg as the laser light was chopped on and off, which shows an excellent reproducibility. Note that there is a dramatic enhancement when Vg changes from 0 to 60 V, which shows the vital effect of voltage manipulation. During the illumination, a trend that the photocurrent decreases with time can be observed. The rapid rise is assigned to the photo-generated electrons swept into graphene, whereas the following decreasement with slow speed is ascribed to the hole injection into graphene during the diffusion process [27]. The photocurrent exhibits a gradual enhancement when the incident power ranges from 10−7 to 10−3 W, as shown in Figure 2D. The photocurrent can be up to 3 × 10−5 A when the intensity of light is 0.1 µW. In comparison, the photoresponse of SOI photodetector without graphene is shown in Figure S3, which shows that the introduction of graphene greatly improves the optoelectronic performance. The maximum responsivity of the GSOI device is calculated to be 2 × 107 A/W, by using the formula
In order to systematically clarify the manipulation effect in such GSOI device, the modeling using Silvaco TCAD tools was carried out to compare with the experiment results. The basic parameters of graphene, such as bandgap, affinity, mobility, etc. were redefined by modifying the new material in database, through which the doping effect of graphene in the FET device has been fully proved [34], [35]. The modeling details are shown in Figure S4 of Supplementary Material. Figure 3A shows the experimental and modeled results about the relationship between Ids and Vg in the dark state, which are in good agreement.
(a) Experimental (black line) and simulated (blue line) transfer characteristics in the dark state. The insets are the corresponding schematic views of the carrier transport under the positive and negative voltages. (b)–(d) Simulated holes distribution in silicon when Vg = 0, −30 and 30 V. Insets are the energy band diagrams.
Figure 3B–D shows the distribution of majority carriers (holes) in top-silicon as Vg = 0, −30 and 30 V, respectively. When Vg = 0 V, the carrier distribution in silicon is only affected by the built-in potential and source-drain bias, as shown in Figure 3B. When Vg = −30 V, the induced holes would accumulate around the interface between the silicon dioxide and top-silicon, and the population of holes in top-silicon is larger than the case of Vg = 0 V, as shown in Figure 3C. Within a certain range, the distribution of holes will become denser as the negative vertical voltage increases. The non-equilibrium carriers generated in silicon will cause the injection of holes into graphene. Moreover, the Fermi energy level of graphene will alter more obviously than silicon [27]. The relevant energy band diagram is shown in the inset of Figure 3C, in which an enhanced built-in electric field is formed with the direction towards graphene. Under illumination, the photogenerated carriers are separated into electrons and holes with the assistance of the enhanced built-in potential, and subsequently the holes will be injected into graphene, which gives rise to an increment of the photocurrent.
When Vg = 30 V, the induced electrons would accumulate around the interface of silicon dioxide and top-silicon, and the number of holes in top-silicon exhibits an obvious decrease comparing with the case Vg = 0 V, as shown in Figure 3D. As the vertical voltage increases, fewer holes (or more electrons) will distribute in top-silicon. This process changes the dynamic equilibrium between the heterojunction and leads to electron injection into graphene. Because the holes in graphene act as the majority carriers, the implantation of electrons into the graphene channel would reduce the source-drain current, which is consistent with the experimental results. With the further increase of the vertical voltage, a large number of electrons are injected into graphene, and the type of majority carrier changes to electrons. The source-drain current would exhibit an increment as the vertical voltage further increases. The Fermi level changes greatly, which is also much larger than the variation of Fermi level in silicon. An increased built-in electric field is formed pointing to top-silicon, which corresponds to the situation under positive vertical voltage in Figure 2B. The relevant energy band is shown in the inset of Figure 3D. Under illumination, electrons are injected into graphene, and the source-drain current would be greatly enhanced. More simulation results about current distribution are shown in Figure S5 of Supplementary Material.
This phenomenon can be explained by the change of resistance in the graphene channel [27], [36], [37].
The Rmodulation represents the total resistance of the device, which consists of the contact resistance Rcontact and the channel resistance Rchannel under dark conditions, as expressed by formula (1). e is the elementary charge, W and L are the width and length of the channel, n and μ are the carrier concentration and carrier mobility, respectively, and Δn is the variation of carrier concentration generated by the voltage manipulation. The contact resistance is very small because there is Ohmic contact between graphene and the electrode. The resistance variation in the graphene channel is mainly dominated by Δn. The Fermi level of silicon nearly does not change under different gate voltages, therefore the variation of Schottky barrier height, ∆Φbi, is equivalent to the shift of graphene work function ∆Φg. Eventually, the Fermi energy of graphene can be expressed as
Next, we discuss the effect of the MPE mechanism on the response time. The corresponding rising and falling times have been measured, as shown in Figure 4A, which can be greatly improved by increasing the vertical voltage. The rising time was reduced from 1 ms to about 100 µs, and the falling time was changed from 1.74 ms to about 200 µs, which are much faster than other reported photogating type devices [23]. Note that our GSOI device enables simultaneously high signal amplification and rapid response. Figure 4B shows the 3 dB bandwidth test results of the GSOI photodetector, in which we can find that the bandwidth is greatly improved when Vg = 30 V in comparison with the case of Vg = 0 V.
(a) Response time of the GSOI device versus the vertical voltage, error bars of Ton and Toff represent the rising and falling time, respectively. (b) 3 dB bandwidth measurement results of the GSOI device under 532 nm illumination when Vg = 0 V and Vg = 30 V, respectively. (c) Simulated distribution of electrons in top-silicon when Vg = 0 V. (d) Simulation concentration gradient formed by electrons in top-silicon when Vg = 30 V.
The process of carrier generation and diffusion in the heterojunction region has a great influence on the photoresponse [24]. The slow diffusion speed gives rise to a long response time. The carrier distribution when Vg = 0 V is shown in Figure 4C, and it can be found that there is nearly no concentration gradient. In contrast, we simulated the distribution of electrons in silicon when Vg = 30 V, as shown in Figure 4D. The vertical voltage causes the accumulation of induced carriers near the insulating layer and produces a decreasing concentration gradient when moving away from the bottom of top-silicon. This concentration gradient will generate a driving force for carrier diffusion and makes more photogenerated carriers diffuse into the heterojunction region, so the transport would be accelerated. Besides, the shortening of the falling time can be mainly ascribed to the enhanced concentration difference between the graphene and top-silicon regions under the positive voltage modulation, which leads to the acceleration of the carrier recombination. More experimental and modeling results about the response times are shown in Figure S6 of Supplementary Material, which clearly demonstrates the manipulation effect of voltage.
To further confirm the role of MPE, we have used heavily p-doped graphene as the device channel instead of the lightly doped ones. The corresponding transfer curve of the device can be seen in Figure S2(b) of the Supplementary Material, which demonstrates the graphene is heavily doped. Also, the relationship between Ids and Vg in the dark state has been modeled to clarify the manipulation mechanism (see Figure S7 of the Supplementary Material). The manipulation effect of vertical voltage on the source-drain current under different optical power is shown in Figure 5A. The net photocurrent can be significantly changed under the manipulation of the vertical voltage. Obviously, as the optical power increases, the photocurrent will be enhanced. Note that the variation trend of Ids is similar to the lightly p-doped GSOI device. The difference is that Ids of the heavily p-doped GSOI device always keeps declining as Vg continuously increases because the type of the majority carriers doesn’t change. Therefore, there is no “inflection point”. Detailly speaking, the holes concentration of such graphene is extremely high, the conversion of majority carrier won’t occur with the increase of Vg. The reliability of the mechanism was further verified by utilizing a moderately p-doped graphene device, as shown in Figure S2 of the Supplementary Material.
(a) Ids as a function of Vg under 532 nm illumination light with different optical power. Vg increases from −60 to 60 V. (b) Ids-Time curve of the device when Vg = 0 V, −30, and 30 V. (c) Responsivity versus light power when Vg = 30 and 0 V. (d) Response time at different vertical voltages.
Figure 5B shows the Ids-Time curve of the device when Vg = 0, −30 and 30 V. It can be seen that Vg not only enhances the photo response greatly but also leads to a negative net photocurrent. This effect can be attributed to the manipulation of top-silicon, which alters the relative position of the energy band between silicon and graphene, and ultimately changes the direction of charge transport. Figure 5C shows the relationship of the responsivity with light power, in which the responsivity magnitude can increase by 5–10 times and reach the order of 106 A/W when Vg = 30 V, compared with the case without vertical voltage. The response time under different Vg is shown in Figure 5D, which exhibits an obvious decrease when Vg becomes positive or negative, and it can be as short as 90 µs. To strictly compare the GSOI photodetector with other reported devices, the detectivity was measured through the noise testing platform [38], the relevant formula is expressed as
where D∗ is specific detectivity, A is device area and NEP is the noise equivalent power. The noise test method is described in detail in Figure S8 of Supplementary Material. Note that the measured detectivity is up to 1.46 × 1013 Jones. Alternatively, we can also directly calculate the detectivity by formula
Summary of device parameters of several typical graphene photodetectors previously reported, and our device, including responsivity, response speed, and normalized detectivity.
| Types of devices | Responsivity | Response speed | Normalized Detectivity |
|---|---|---|---|
| Graphene–metal junction [28] | 6.1 mA/W | 4 ps | – |
| Graphene–silicon heterojunction [41], [42] | 0.435 A/W | 160 µs | 2.1 × 108 Jones |
| Graphene–silicon heterojunction in conductor mode [27] | 104 A/W | 60 µs | – |
| Graphene–silicon in QCR mode [23] | 106–107 A/W | 1.8 ms | 7.69 × 109 Jones |
| Graphene-dioxide silicon /silicon [26] | 103 A/W | 400 ns | 1.1 × 1010 Jones |
| Graphene–silicon-on-insulator [43] | 0.23 A/W | 20 ns | 7.83 × 1010 Jones |
| Graphene-n-type silicon heterojunction [44] | 0.73 A/W | 750 µs | 5.77 × 1013 Jones (calculated) |
| Our device: Graphene/silicon-on-insulator (GSOI) in conductor mode | 107 A/W | 90 µs | 1.46 × 1013 Jones (measured) 1 × 1014 Jones (calculated) |
3 Conclusion
In this paper, a mechanism based on GSOI hybrid structure was proposed for the first time to obtain an adjustable built-in potential between graphene and silicon, which brings in an enhanced responsivity and fast response time. At the same time, due to the voltage manipulation, the concentration gradient of major carriers from the silicon to graphene is generated, which makes the photogenerated carriers diffuse rapidly to the depletion layer, thus the response time can be shortened. By manipulation, the responsivity can be increased from 105 to 107 A/W, and the response time is decreased from about 1000–90 µs for the GSOI device. The reliability of this manipulation mechanism is verified by a series of experiments and simulations with different doping types of graphene. The GSOI structure and manipulation mechanism in this paper pave the way to explore novel photodetectors with intriguing performance.
4 Methods
4.1 Device fabrication
For the photodetector fabrication, the SOI substrates were chosen, in which the thicknesses of top-silicon and bottom-silicon are 220 and 500 µm, respectively, and the thickness of the middle oxide layer is 2 µm. The primary specification parameter of the SOI can be seen in Section S9 of the Supplementary Material. The phosphorus doping concentrations for both silicon layers are 1 × 1015 cm−3. To transfer graphene films onto the patterned substrates, the graphene-coated Cu foil was firstly spin-coated with polymethyl methacrylate (PMMA) and baked on a hot plate at 150 °C for 10 min. Subsequently, a mixed solution of hydrochloric acid and Hydrogen peroxide was used as an etchant, to remove the copper films. Lastly, the PMMA films were dissolved by using acetone after the accomplishment of the transfer process.
To make the electrodes, two kinds of photoresists, namely LOR and S1805, were successively spin-coated onto the graphene surface. After that, these photoresists were exposed and developed in AZ300 solution. Au film (50 nm) was sputtered onto the graphene surface by using e-beam evaporation, and will not directly contact with the top-silicon. Both the source and drain electrodes were obtained by dissolving the unexposed photoresists using the acetone solution.
To make the graphene film into strips, a second bilayer photolithography process was utilized. After the development, the uncovering graphene was etched by using oxygen for about 30 s. Lastly, the GSOI devices with the graphene strips of 10 × 10 μm) were obtained by dissolving the remaining photoresists in AZ400 solution.
4.2 Test characterization
The chip package was inserted into a socket located inside a home-built chamber connected to a Keithley semiconductor analyzer (SCS4200) for electrical measurements under ambient conditions. Three probes were connected to SUM 1, SUM 2, and SUM three of SCS 4200. When measuring the manipulation curve, the source-drain bias was applied to 1 V, and the gate voltage was scanned from −60 to 60 V. The vertical voltage and source-drain bias remained unchanged when measuring the transient characteristics photoresponse. The response time was measured by a 7510-oscilloscope, which can guarantee the precise measurement of photoresponse with subtle magnitude.
4.3 Numerical simulation
The simulation model was solved by the finite element method based on a two-dimensional system. Simulations of the structures have been carried out by self-consistently solving the 2D electrostatic and transport equations. In particular, we solve
Among them, Jn and Jp are the current densities of electrons and holes, q is the single-electron charge, ε is the dielectric constant, n and p are the concentration of free electrons and holes. μn and μp denote the mobility of electrons and holes, Dn, and Dp represent the diffusion coefficient of electrons and holes, respectively, and ψ is the potential. Assume that
Because the device is in steady-state when it works stably, it can be considered that the concentration of electrons and holes does not change as the time varies. Thus,
U denotes the difference between net production rate G and compound rate R, thus
Among them,
The intensity attenuation of monochromatic light through semiconductor materials can be expressed as follows:
where I0 is the intensity of the incident light, and α is the absorption coefficient of the material. Generally, the absorption coefficient has a relationship with the wavelength. Given the relationship between photon absorption and electron-hole pair generation, carrier generation rate and light attenuation in semiconductors can be judged. Therefore, the light generation rate can be obtained as follows
The GL0 in the above formula is the optical absorptivity on the semiconductor surface. For the reciprocal 1/α of the absorptivity, it is a dimension of length, representing the average penetration depth in the material.
When a light source is added to Silvaco TCAD to irradiate the semiconductor devices, the reflection and projection coefficients of each optical path, the loss caused by absorption and other factors will be accumulatively analyzed in the calculation. The following formulas will be used for light generation in materials:
The physical quantities represented by the parameters in the formula are as follows: P is the intensity of the beam, which includes all factors affecting the reflection, transmission of the beam and attenuation due to the absorption in the propagation process; η0 is the internal quantum efficiency, i.e. the number of electron holes produced by each incident photon; y is the relative distance of propagation in the solution process; h, c, and λ are Planck constants, light speed, and incident light wavelength, respectively; α is the absorption coefficient of the material.
Surface recombination is considered as a possible loss mechanism at the semiconductor interface, especially for bulk heterojunction materials with high mobility. Contact current is the equation of excess carrier concentration. That is to say, electron current density
The properties of the contact end depend on the surface recombination rate
Funding source: Natural Science Foundation of Chongqing, China
Award Identifier / Grant number: cstc2019jcyjjqX0017
Funding source: National Key R&D Program of China
Award Identifier / Grant number: 2017YFE0131900
Acknowledgments
This work was supported by the National Key R&D Program of China (2017YFE0131900), and Natural Science Foundation of Chongqing, China (cstc2019jcyjjqX0017).
References
[1] F. H. L. Koppens, T. Mueller, Ph. Avouris, A. C. Ferrari, M. S. Vitiello, and M. Polini, “Photodetectors based on graphene, other two-dimensional materials and hybrid systems,” Nat. Nanotechnol., vol. 9, pp. 780–793, 2014, https://doi.org/10.1038/nnano.2014.215.Search in Google Scholar
[2] P. Avouris and M. Freitag, “Graphene photonics, plasmonics, and optoelectronics,” IEEE J. Sel. Top. Quantum. Electron., vol. 20, 2014, Art no. 6000112, https://doi.org/10.1109/jstqe.2013.2272315.Search in Google Scholar
[3] F. Bonaccorso, Z. Sun, T. Hasan, and A. C. Ferrari, “Graphene photonics and optoelectronics,” Nat. Photon., vol. 4, pp. 611–622, 2010, https://doi.org/10.1038/nphoton.2010.186.Search in Google Scholar
[4] N. Guo, W. D. Hu, T. Jiang, et al., “High-quality infrared imaging with graphene photodetectors at room temperature,” Nanoscale., vol. 8, pp. 16065–16072, 2016, https://doi.org/10.1039/c6nr04607j.Search in Google Scholar
[5] L. Tong, X. Y. Huang, P. Wang, et al., “Stable mid-infrared polarization imaging based on quasi-2D tellurium at room temperature,” Nat. Commun., vol. 11, p. 2308, 2020, https://doi.org/10.1038/s41467-020-16125-8.Search in Google Scholar
[6] Q. J. Liang, Q. X. Wang, Q. Zhang, et al., “High-performance, room temperature, ultra-broadband photodetectors based on air-stable PdSe2,” Adv. Mater., vol. 31, 2019, Art no. 1807609, https://doi.org/10.1002/adma.201807609.Search in Google Scholar
[7] R. R. Nair, P. Blake, A.N. Grigorenko, et al., “Fine structure constant defines visual transparency of graphene,” Science., vol. 320, pp. 1308–1308, 2008, https://doi.org/10.1126/science.1156965.Search in Google Scholar
[8] M. Engel, M. Steiner, A. Lombardo, et al., “Light-Matter interaction in a microcavity-controlled graphene transistor,” Nat. Commun., vol. 3, p. 906, 2012, https://doi.org/10.1038/ncomms1911.Search in Google Scholar
[9] M. Furchi, A. Urich, A. Pospischil, et al., “Microcavity-Integrated graphene photodetector,” Nano. Lett., vol. 12, pp. 2773–2777, 2012, https://doi.org/10.1021/nl204512x.Search in Google Scholar
[10] B. Zhao, J. M. Zhao, and Z. M. Zhang, “Enhancement of near-infrared absorption in graphene with metal gratings,” Appl. Phys. Lett., vol. 105, p. 031905, 2014, https://doi.org/10.1063/1.4890624.Search in Google Scholar
[11] T. J. Echtermeyer, L. Britnell, P. K. Jasnos, et al., “Strong plasmonic enhancement of photovoltage in graphene,” Nat. Commun., vol. 2, p. 458, 2011, https://doi.org/10.1038/ncomms1464.Search in Google Scholar
[12] Z. Y. Fang, Y. M. Wang, Z. Liu, et al., “Plasmon-Induced doping of graphene,” Acs. Nanotechnol., vol. 6, pp. 10222–10228, 2012, https://doi.org/10.1021/nn304028b.Search in Google Scholar
[13] H. H. Fang and W. D. Hu, “Photogating in low dimensional photodetectors,” Adv. Sci., vol. 4, p. 1700323, 2017, https://doi.org/10.1002/advs.201700323.Search in Google Scholar
[14] G. Konstantatos, M. Badioli, L. Gaudreau, et al., “Hybrid graphene-quantum dot photo transistors with ultrahigh gain,” Nat Nanotechnol., vol. 7, pp. 363–368, 2012, https://doi.org/10.1038/nnano.2012.60.Search in Google Scholar
[15] Z. H. Sun, Z. K. Liu, J. H. Li, G. A. Tai, S. P. Lau, and F. Yan, “Infrared photodetectors based on CVD-grown graphene and Pbs quantum dots with ultrahigh responsivity,” Adv. Mater., vol. 24, pp. 5878–5883, 2012, https://doi.org/10.1002/adma.201202220.Search in Google Scholar
[16] Y. Lee, J. Kwon, E. Hwang, et al., “High-performance perovskite-graphene hybrid photodetector,” Adv. Mater., vol. 27, pp. 41−46, 2015, https://doi.org/10.1002/adma.201402271.Search in Google Scholar
[17] Y. Liu, F. Wang, X. Wang, et al., “Planar carbon nanotube-graphene hybrid films for high-performance broadband photodetectors,” Nat. Commun., vol. 6, p. 8589, 2015, https://doi.org/10.1038/ncomms9589.Search in Google Scholar
[18] K. Roy, M. Padmanabhan, S. Goswami, et al., “Graphene−MoS2 hybrid structures for multifunctional photoresponsive memory devices,” Nat. Nanotechnol., vol. 8, pp. 826−830, 2013, https://doi.org/10.1038/nnano.2013.206.Search in Google Scholar
[19] F. H. L. Koppens, T. Mueller, P. Avouris, A. C. Ferrari, M. S. Vitiello, and M. Polini, “Photodetectors based on graphene, other two-dimensional materials and hybrid systems,” Nat. Nanotechnol., vol. 9, pp. 780−793, 2014, https://doi.org/10.1038/nnano.2014.215.Search in Google Scholar
[20] Q. S. Guo, A. Pospischil, M. Bhuiyan, et al., “Black phosphorus mid-infrared photodetectors with high gain,” Nano. Lett., vol. 16, p. 4648, 2016, https://doi.org/10.1021/acs.nanolett.6b01977.Search in Google Scholar
[21] C. Soci, A. Zhang, B. Xiang, et al., “ZnO nanowire UV photodetectors with high internal gain,” nanosci. Nanotechnol., vol. 10, p. 1430, 2010, https://doi.org/10.1166/jnn.2010.2157.Search in Google Scholar
[22] G. Konstantatos, M. Badioli, L. Gaudreau, et al., “Graphene−Quantum dot phototransistors with ultrahigh gain,” Nat. Nanotechnol., vol. 7, pp. 363–368, 2012, https://doi.org/10.1038/nnano.2012.60.Search in Google Scholar
[23] F. Z. Liu and S. Kar, “Quantum carrier reinvestment-induced ultrahigh and broadband photocurrent responses in graphene-silicon junctions,” Acs. Nano., vol. 8, pp. 10270–10279, 2014, https://doi.org/10.1021/nn503484s.Search in Google Scholar
[24] I. Nikitskiy, S. Goossens, D. Kufer, et al., “Integrating an electrically active colloidal quantum dot photodiode with a graphene phototransistor,” Nat. Commun., vol. 7, 2016, Art no. 11954 https://doi.org/10.1038/ncomms11954.Search in Google Scholar
[25] B. Radisavljevic and A. Kis, “Mobility engineering and a metal-insulator transition in monolayer MoS2,” Nat. Mater., vol. 12, pp. 815–820, 2013, https://doi.org/10.1038/nmat3687.Search in Google Scholar
[26] X. T. Guo, W. H. Wang, H. Nan, et al., “High-performance graphene photodetector using interfacial gating,” Optica., vol. 3, pp. 1066–1070, 2016, https://doi.org/10.1364/optica.3.001066.Search in Google Scholar
[27] Z. F. Chen, Z. Z. Cheng, J. Q. Wang, et al., “High responsivity, broadband, and fast graphene/silicon photodetector in photoconductor mode,” Adv. Opt. Mat., vol. 3, pp. 1207–1214, 2015, https://doi.org/10.1002/adom.201500127.Search in Google Scholar
[28] F. Xia, T. Mueller,Y.-M. Lin, A. Valdes-Garcia, and P. Avouris, “Ultrafast graphene photodetector,” Nat. Nanotechnol., vol. 4, pp. 839−843, 2009, https://doi.org/10.1038/nnano.2009.292.Search in Google Scholar
[29] Y. Liu, R. Cheng, L. Liao, et al., “Plasmon resonance enhanced multicolour photodetection by graphene,” Nat. Commun., vol. 2, p. 579, 2011, https://doi.org/10.1038/ncomms1589.Search in Google Scholar
[30] J. J. Liu, Y. L. Yin, L. H. Yu, Y. Shi, D. Liang, and D. Dai, “Silicon–Graphene conductive photodetector with ultra-high responsivity,” Sci. Reports., vol. 7, 2017, Art no. 40904, https://doi.org/10.1038/srep40904.Search in Google Scholar
[31] S. Riazimehr, S. Kataria, J. M. Gonzalez-Medina, et al., “High responsivity and quantum efficiency of graphene/silicon photodiodes achieved by interdigitating Schottky and gated regions,” Acs Photon., vol. 6, pp. 107–115, 2019, https://doi.org/10.1021/acsphotonics.8b00951.Search in Google Scholar
[32] K. S. Novoselov, A. K. Geim, S. V. Morozov, et al., “Electric field effect in atomically thin carbon films,” Science., vol. 306, pp. 666–669, 2004, https://doi.org/10.1126/science.1102896.Search in Google Scholar
[33] D. Reddy, L. F. Register, G. D. Carpenter, and S. K. Banerjee, “Graphene field-effect transistors,” J. Phy. D-Appl. Phy., vol. 45, 2012, Art no. 019501, https://doi.org/10.1088/0022-3727/45/1/019501.Search in Google Scholar
[34] M. S. Mobarakeh, N. Moezi, M. Vali, and D. Dideban, “A novel graphene tunnelling field effect transistor (GTFET) using bandgap engineering,” Superlatt. Microstruct., vol. 100, pp. 1221–1229, 2016, https://doi.org/10.1016/j.spmi.2016.11.007.Search in Google Scholar
[35] A. Safari, M. Dousti, and M. B. Tavakoli, “Monolayer graphene field effect transistor-based operational amplifier,” J. Circuits Sys. Comp., vol. 28, 2019, Art no. 1950052, https://doi.org/10.1142/s021812661950052x.Search in Google Scholar
[36] K. Chen, X. Wan, D. Q. Liu, et al., “Quantitative determination of scattering mechanism in large-area graphene on conventional and SAM-functionalized substrates at room temperature,” Nanoscale., vol. 5, p. 5784, 2013, https://doi.org/10.1039/c3nr00972f.Search in Google Scholar
[37] X. S. Li, C. W. Magnuson, A. Venugopal, et al., “Large-area graphene single crystals grown by low-pressure chemical vapor deposition of methane on copper,” Am. Chem. Soc., vol. 133, p. 2816, 2011, https://doi.org/10.1021/ja109793s.Search in Google Scholar
[38] Y. J. Fang, A. Armin, P. Meredith, and J. S. Huang, “Accurate characterization of next-generation thin-film photodetectors,” Nat. photon., vol. 13, pp. 1–4, 2019, https://doi.org/10.1038/s41566-018-0288-z.Search in Google Scholar
[39] K. E. Chang, C. Kim, T. J. Yoo, et al., “High-responsivity near-infrared photodetector using gate-modulated graphene/germanium Schottky junction,” Adv. Electronic Mater., vol. 5, 2019, Art no. 1800957, https://doi.org/10.1002/aelm.201800957.Search in Google Scholar
[40] J. Shen, X. Z. Liu, X. F. Song, et al., “High-performance Schottky heterojunction photodetector with directly grown graphene nanowalls as electrodes,” Nanoscale., vol. 9, pp. 6020–6025, 2017, https://doi.org/10.1039/c7nr00573c.Search in Google Scholar
[41] X. An, F. Liu, Y. J. Jung, and S. Kar, “Tunable graphene-silicon heterojunctions for ultrasensitive photodetection,” Nano. Lett., vol. 13, pp. 909−916, 2013, https://doi.org/10.1021/nl303682j.Search in Google Scholar
[42] Y. B. An, A. Behnam, E. Pop, and A. Ural, “Metal-semiconductor-metal photodetectors based on graphene/p-type silicon Schottky junctions,” Appl. Phys. Lett., vol. 102, 2013, Art no. 013110, https://doi.org/10.1063/1.4773992.Search in Google Scholar
[43] H. Selvi, E. W. Hill, P. Parkinson, and T. J. Echtermeyer, “Graphene-silicon-on-insulator (GSOI) Schottky diode photodetectors,” Nanoscale., vol. 10, pp. 18926–18935, 2018, https://doi.org/10.1039/c8nr05285a.Search in Google Scholar
[44] X. M. Li, M. Zhu, M. D. Du, et al., “High detectivity graphene-silicon heterojunction photodetector,” Small., vol. 12, pp. 595–601, 2016, https://doi.org/10.1002/smll.201502336.Search in Google Scholar
Supplementary Material
The online version of this article offers supplementary material (https://doi.org/10.1515/nanoph-2020-0261).
© 2020 Hao Jiang et al., published by De Gruyter, Berlin/Boston
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