High Responsivity and Quantum Efficiency of Graphene / Silicon Photodiodes Achieved by Interdigitating Schottky and Gated Regions

TL;DR

This paper demonstrates a novel graphene/silicon photodiode design with interdigitated Schottky and GIS regions, achieving high quantum efficiency and responsivity, supported by experimental results and simulations.

Contribution

It introduces an interdigitated contact pattern for G/Si photodiodes that significantly enhances efficiency and responsivity, with a new standard for defining active area.

Findings

Achieved >80% EQE across 380-930 nm wavelengths.

Maximum EQE of 98% at 850 nm with 635 mA/W responsivity.

Experimental results supported by numerical simulations.

Abstract

Graphene / silicon (G/Si) heterostructures have been studied extensively in the past years for applications such as photodiodes, photodetectors and solar cells, with a growing focus on efficiency and performance. Here, a specific contact pattern scheme with interdigitated Schottky and graphene/insulator/silicon (GIS) structures is explored to experimentally demonstrate highly sensitive G/Si photodiodes. With the proposed design, an external quantum efficiency (EQE) of > 80 % is achieved for wavelengths ranging from 380 to 930 nm. A maximum EQE of 98% is observed at 850 nm, where the responsivity peaks to 635 mA/W, surpassing conventional Si p-n photodiodes. This efficiency is attributed to the highly effective collection of charge carriers photogenerated in Si under the GIS parts of the diodes. The experimental data is supported by numerical simulations of the diodes. Based on these results, a definition for the true active area in G/Si photodiodes is proposed, which may serve towards standardization of G/Si based optoelectronic devices.