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Integration of Nanometer-Thick 1T-TaS2 Films with Silicon for an Optically Driven Wide-Band Terahertz Modulator
ACS Applied Nano Materials ( IF 5.3 ) Pub Date : 2020-10-21 , DOI: 10.1021/acsanm.0c02076
Alka Jakhar 1 , Prabhat Kumar 2 , Sajid Husain 3 , Veerendra Dhyani 1 , Samaresh Das 1
Affiliation  

The amplitude of terahertz (THz) waves is modulated optically by a pumping laser source, and the effect of optical power on modulation depth is systematically investigated in this work. The reported THz modulator is based on a conducting transition metal dichalcogenide (TMD), that is, a nanometer-thick thin film of tantalum disulfide (TaS2) grown on a high-resistivity silicon (Si) substrate. The Raman spectrum confirms the formation of the 1T phase of TaS2. Modulation depths of 69.3 and 46.8% have been achieved at 0.1 THz and 0.9 THz frequency, respectively, under a low pumping power of 1 W/cm2. A constant higher modulation depth in the wide frequency range reveals the broadband response of the THz modulator. Under the same conditions, the modulation increased twice as compared to bare Si after annealing at 300 °C in the presence of air. Furthermore, numerical analysis based on the finite-difference time domain shows that a greater number of photogenerated charge carriers are present near the interface of Si and TaS2, which leads to enhancement in modulation. The utilization of 1T-TaS2 imparts potential to these TMDs in the wide THz frequency range and unfolds the possibilities for their use in THz imaging, wireless communication, and detection processes.

中文翻译:

纳米厚度的1T-TaS 2薄膜与硅的集成,用于光驱动宽带太赫兹调制器

太赫兹(THz)波的振幅由泵浦激光源进行光学调制,并且在这项工作中系统地研究了光功率对调制深度的影响。报道的THz调制器基于导电过渡金属二硫化碳(TMD),即在高电阻率的硅(Si)衬底上生长的纳米厚度的二硫化钽(TaS 2)薄膜。拉曼光谱证实了TaS 2的1T相的形成。在1 W / cm 2的低泵浦功率下,分别在0.1 THz和0.9 THz频率下实现了69.3和46.8%的调制深度。在较宽的频率范围内恒定的较高调制深度揭示了THz调制器的宽带响应。在相同条件下,在空气中于300°C退火后,调制比裸Si调制提高两倍。此外,基于有限差分时域的数值分析表明,在Si和TaS 2的界面附近存在大量的光生电荷载流子,这导致了调制的增强。1T-TaS 2的利用为这些TMD提供了广阔的THz频率范围的潜力,并揭示了它们在THz成像,无线通信和检测过程中使用的可能性。
更新日期:2020-11-25
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