Approaching the Intrinsic Threshold Breakdown Voltage and Ultrahigh Gain in a Graphite/InSe Schottky Photodetector.

Zhang, Zhiyi; Cheng, Bin; Lim, Jeremy; Gao, Anyuan; Lyu, Lingyuan; Cao, Tianjun; Wang, Shuang; Li, Zhu-An et al. · Adv Mater · 2022

basic_science · Level V

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Abstract

Realizing both ultralow breakdown voltage and ultrahigh gain is one of the major challenges in the development of high-performance avalanche photodetector. Here, it is reported that an ultrahigh avalanche gain of 3 × 10<sup>5</sup> can be realized in the graphite/InSe Schottky photodetector at a breakdown voltage down to 5.5 V. Remarkably, the threshold breakdown voltage can be further reduced down to 1.8 V by raising the operating temperature, approaching the theoretical limit of 1.5 <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics> <mrow><msub><mi>E</mi> <mi>g</mi></msub> </mrow> <annotation>\[{{\cal E}_{\bf g}}\]</annotation></semantics> </math> /e, with <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics> <mrow><msub><mi>E</mi> <mi>g</mi></msub> </mrow> <annotation>${{\cal E}_{\bf g}}$</annotation></semantics> </math> the bandgap of semiconductor. A 2D impact ionization model is developed and it is uncovered that observation of high gain at low breakdown voltage arises from reduced dimensionality of electron-phonon scattering in the layered InSe flake. These findings open up a promising avenue for developing novel weak-light detectors with low energy consumption and high sensitivity.