# Towards Substrate Engineering of Graphene-Silicon Schottky Diode Photodetectors

## TL;DR

This study systematically explores how interfacial oxide layers, fabrication methods, and silicon substrates affect the performance of graphene-silicon Schottky diode photodetectors across a broad spectrum, highlighting design strategies for enhanced photodetection.

## Contribution

It provides a comprehensive analysis of the effects of fabrication parameters and substrate choices on device performance, offering insights for substrate engineering in photodetector development.

## Key findings

- Interfacial oxide layers can enhance photodetection properties.
- Devices operate from near-UV to mid-infrared with high responsivity.
- Achieved rise/fall times of tens of nanoseconds.

## Abstract

Graphene-Silicon Schottky diode photodetectors possess beneficial properties such as high responsivities and detectivities, broad spectral wavelength operation and high operating speeds. Various routes and architectures have been employed in the past to fabricate devices. Devices are commonly based on the removal of the silicon-oxide layer on the surface of silicon by wet-etching before deposition of graphene on top of silicon to form the graphene-silicon Schottky junction. In this work, we systematically investigate the influence of the interfacial oxide layer, the fabrication technique employed and the silicon substrate on the light detection capabilities of graphene-silicon Schottky diode photodetectors. The properties of devices are investigated over a broad wavelength range from near-UV to short-/mid-infrared radiation, radiation intensities covering over five orders of magnitude as well as the suitability of devices for high speed operation. Results show that the interfacial layer, depending on the required application, is in fact beneficial to enhance the photodetection properties of such devices. Further, we demonstrate the influence of the silicon substrate on the spectral response and operating speed. Fabricated devices operate over a broad spectral wavelength range from the near-UV to the short-/mid-infrared (thermal) wavelength regime, exhibit high photovoltage responses approaching 10$^6$ V/W and short rise- and fall-times of tens of nanoseconds.