The fabrication of graphene-silicon (Gr-Si) junction inolves the formation of a parallel metal-insulator-semiconductor (MIS) structure, which is often disregarded but plays an important role in the optoelectronic properties of the device. In this work, the transfer of graphene onto a patterned n-type Si substrate, covered by Si3N4, produces a Gr-Si device in which the parallel MIS consists of a Gr−Si3N4−Si structure surrounding the Gr-Si junction. The Gr-Si device exhibits rectifying behavior with a rectification ratio up to 104. The investigation of its temperature behavior is necessary to accurately estimate the Schottky barrier height at zero bias, ϕb0=0.24eV, the effective Richardson's constant, A∗=7⋅10−10AK−2cm−2, and the diode ideality factor n=2.66 of the Gr-Si junction. The device is operated as a photodetector in both photocurrent and photovoltage mode in the visible and infrared (IR) spectral regions. A responsivity up to 350 mA/W and external quantum efficiency (EQE) up to 75% is achieved in the 500-1200 nm wavelength range. A decrease of responsivity to 0.4 mA/W and EQE to 0.03% is observed above 1200 nm, that is in the IR region beyond the silicon optical bandgap, in which photoexcitation is driven by graphene. Finally, a model based on two back-to-back diodes, one for the Gr-Si junction. the other for the Gr−Si3N4−Si MIS structure, is proposed to explain the electrical behavior of the Gr-Si device.
@article{arxiv.2105.09655,
title = {Graphene-silicon device for visible and infrared photodetection},
author = {Aniello Pelella and Alessandro Grillo and Enver Faella and Giuseppe Luongo and Mohammad Bagher Askari and Antonio Di Bartolomeo},
journal= {arXiv preprint arXiv:2105.09655},
year = {2021}
}