Photocurrent generation at ABA/ABC lateral junction in tri-layer graphene photodetector

TL;DR

This study demonstrates photocurrent generation at ABA/ABC stacking domain junctions in tri-layer graphene, driven by the photo-thermoelectric effect, with potential advantages over traditional metal-graphene-metal photodetectors.

Contribution

It reveals a novel photocurrent generation mechanism at stacking domain junctions in tri-layer graphene, expanding understanding beyond metal-graphene interfaces.

Findings

Photocurrent generated in the middle of the graphene channel.

Responsivity of 0.18 A/W observed.

Photocurrent direction depends on back-gate bias.

Abstract

Metal-graphene-metal photodetectors utilize photocurrent generated near the graphene/metal junctions and have many advantages including high speed and broad-band operation. Here, we report on photocurrent generation at ABA/ABC stacking domain junctions in tri-layer graphene with a responsivity of 0.18 A/W. Unlike usual metal-graphene-metal devices, the photocurrent is generated in the middle of the graphene channel, not confined to the vicinity of the metal electrodes. The magnitude and the direction of the photocurrent depend on the back-gate bias. Theoretical calculations show that there is a built-in band offset between the two stacking domains, and the dominant mechanism of the photocurrent is the photo-thermoelectric effect due to the Seebeck coefficient difference.