Approaching intrinsic threshold breakdown voltage and ultra-high gain in graphite/InSe Schottky photodetector

TL;DR

This paper demonstrates a graphite/InSe Schottky photodetector achieving ultra-high gain at very low breakdown voltages, with insights into the impact ionization process in layered 2D materials, advancing high-performance weak-light detection.

Contribution

The study introduces a novel 2D impact ionization model explaining high gain at low breakdown voltage in layered InSe, enabling ultra-sensitive, low-energy photodetectors.

Findings

Achieved avalanche gain of 3×10^5 at 5.5 V breakdown voltage.

Reduced threshold breakdown voltage to 1.8 V by increasing temperature.

Developed a 2D impact ionization model explaining high gain in layered InSe.

Abstract

Realizing both ultra-low breakdown voltage and ultra-high gain has been one of the major challenges in the development of high-performance avalanche photodetector. Here, we report that an ultra-high avalanche gain of 3*10^5 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 1.5E_g/e with E_g the band gap of semiconductor. We develop a two-dimensional impact ionization model and uncover that observation of high gain at low breakdown voltage arises from reduced dimensionality of electron-phonon (e-ph) scattering in the layered InSe flake. Our findings open up a promising avenue for developing novel weak-light detectors with low energy consumption and high sensitivity.