We report on the demonstration of atomic layer van der Waals (vdW) heterostructure photodiodes operating in the visible regime, enabled by stacking single- to few-layer n-type molybdenum disulfide (MoS₂) on top of few-layer p-type gallium selenide (GaSe) crystals. The atomic layer vdW photodiode exhibits an excellent photoresponsivity of ∼3A/W at the wavelength of 532 nm when symmetric few-layer graphene (FLG) contacts with low contact resistance are used. On the other hand, for a GaSe/MoS₂ photodiode with asymmetric GaSe/FLG and MoS₂/gold (Au) contacts, a very low noise equivalent power of NEP ∼ 10^–14 W/ is obtained due to dark current reduction, which demonstrates the feasibility of detecting sub-pW (<10^–12 W) level optical illumination. Further, the same photodiode exhibits a large linear dynamic range of DR ≈ 70 dB due to the remarkable photocurrent to dark current ratio. These results show that not only the p–n junction formed at the interface between p-type GaSe and n-type MoS₂ but also the metal–semiconductor junction with each 2D material play a pivotal role in determining the diode characteristics and photoresponse of the vdW photodiodes.

中文翻译：

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具有低噪声和大动态范围的原子层GaSe / MoS ₂范德华异质结构光电二极管

我们报告了在可见态下操作的原子层范德华（vdW）异质结构光电二极管的演示，该方法通过在单层p型镓的几层上堆叠单层至几层n型二硫化钼（MoS ₂）来实现硒化物（GaSe）晶体。当使用具有低接触电阻的对称几层石墨烯（FLG）接触时，原子层vdW光电二极管在532 nm的波长下具有约3A / W的出色光响应性。另一方面，对于具有不对称GaSe / FLG和MoS ₂ /金（Au）触点的GaSe / MoS ₂光电二极管，由于暗电流降低，因此获得了非常低的NEP〜10 ^–14 W /噪声等效功率。证明了检测低于pW（​​<10^–12 W）级别的光学照明。此外，由于显着的光电流与暗电流之比，同一光电二极管表现出大的线性动态范围DR≈70 dB。这些结果表明，不仅在p型GaSe和n型MoS ₂之间的界面处形成的p–n结，而且与每种2D材料的金属-半导体结在决定二极管的特性和光响应方面都起着关键作用。 vdW光电二极管。