Spatially controlled electrostatic doping in graphene p-i-n junction for hybrid silicon photodiode

TL;DR

This paper presents a scalable, graphene-silicon p-i-n photodiode with spatially controlled electrostatic doping, achieving ultrafast, zero-bias photodetection with high signal-to-noise ratio and potential for quantum efficiency enhancement.

Contribution

It introduces a novel, post-fabrication-free graphene-silicon photodiode with deterministic control of the space charge region, enabling ultrafast, high-performance optoelectronic detection.

Findings

Over 50 dB signal-to-noise ratio at 40 GHz

Zero-bias operation with visible to near-infrared detection

Potential for quantum efficiency amplification via hot carriers and avalanche effects

Abstract

Sufficiently large depletion region for photocarrier generation and separation is a key factor for two-dimensional material optoelectronic devices, but few device configurations has been explored for a deterministic control of a space charge region area in graphene with convincing scalability. Here we investigate a graphene-silicon p-i-n photodiode defined in a foundry processed planar photonic crystal waveguide structure, achieving visible - near-infrared, zero-bias and ultrafast photodetection. Graphene is electrically contacting to the wide intrinsic region of silicon and extended to the p an n doped region, functioning as the primary photocarrier conducting channel for electronic gain. Graphene significantly improves the device speed through ultrafast out-of-plane interfacial carrier transfer and the following in-plane built-in electric field assisted carrier collection. More than 50 dB converted signal-to-noise ratio at 40 GHz has been demonstrated under zero bias voltage, with quantum efficiency could be further amplified by hot carrier gain on graphene-i Si interface and avalanche process on graphene-doped Si interface. With the device architecture fully defined by nanomanufactured substrate, this study is the first demonstration of post-fabrication-free two-dimensional material active silicon photonic devices.