光电探测器
材料科学
响应度
光电子学
红外线的
碲
带隙
半导体
折射率
比探测率
吸光度
电子迁移率
光学
物理
冶金
作者
Matin Amani,Chaoliang Tan,George Zhang,Chunsong Zhao,James Bullock,Xiaohui Song,Hyung‐Jin Kim,Vivek Raj Shrestha,Yang Gao,Kenneth B. Crozier,Mary Scott,Ali Javey
出处
期刊:ACS Nano
[American Chemical Society]
日期:2018-06-18
卷期号:12 (7): 7253-7263
被引量:392
标识
DOI:10.1021/acsnano.8b03424
摘要
Two-dimensional (2D) materials, particularly black phosphorus (bP), have demonstrated themselves to be excellent candidates for high-performance infrared photodetectors and transistors. However, high-quality bP can be obtained only via mechanical exfoliation from high-temperature- and high-pressure-grown bulk crystals and degrades rapidly when exposed to ambient conditions. Here, we report solution-synthesized and air-stable quasi-2D tellurium (Te) nanoflakes for short-wave infrared (SWIR) photodetectors. We perform comprehensive optical characterization via polarization-resolved transmission and reflection measurements and report the absorbance and complex refractive index of Te crystals. It is found that this material is an indirect semiconductor with a band gap of 0.31 eV. From temperature-dependent electrical measurements, we confirm this band-gap value and find that 12 nm thick Te nanoflakes show high hole mobilities of 450 and 1430 cm2 V–1 s–1 at 300 and 77 K, respectively. Finally, we demonstrate that despite its indirect band gap, Te can be utilized for high-performance SWIR photodetectors by employing optical cavity substrates consisting of Au/Al2O3 to dramatically increase the absorption in the semiconductor. By changing the thickness of the Al2O3 cavity, the peak responsivity of Te photoconductors can be tuned from 1.4 μm (13 A/W) to 2.4 μm (8 A/W) with a cutoff wavelength of 3.4 μm, fully capturing the SWIR band. An optimized room-temperature specific detectivity (D*) of 2 × 109 cm Hz1/2 W–1 is obtained at a wavelength of 1.7 μm.
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