Deep-ultraviolet electroluminescence and photocurrent generation in graphene/hBN/graphene heterostructures

TL;DR

This paper demonstrates deep-ultraviolet electroluminescence and photocurrent generation in graphene/hBN/graphene heterostructures at room temperature, highlighting their potential for DUV light emission and detection devices.

Contribution

It is the first to show room-temperature DUV electroluminescence from hBN via tunneling in heterostructures, and explores photocurrent generation mechanisms.

Findings

Electroluminescence observed at DUV frequencies in heterostructures.

Photocurrent generated under DUV laser illumination and bias.

Recombination processes mainly from pristine hBN and stacking faults.

Abstract

Hexagonal boron nitride (hBN) is a van der Waals semiconductor with a wide bandgap of ~ 5.96 eV. Despite the indirect bandgap characteristics of hBN, charge carriers excited by high energy electrons or photons efficiently emit luminescence at deep-ultraviolet (DUV) frequencies via strong electron-phonon interaction, suggesting potential DUV light emitting device applications. However, electroluminescence from hBN has not been demonstrated at DUV frequencies so far. In this study, we report DUV electroluminescence and photocurrent generation in graphene/hBN/graphene heterostructures at room temperature. Tunneling carrier injection from graphene electrodes into the band edges of hBN enables prominent electroluminescence at DUV frequencies. On the other hand, under DUV laser illumination and external bias voltage, graphene electrodes efficiently collect photo-excited carriers in hBN, which generates high photocurrent. Laser excitation micro-spectroscopy shows that the radiative recombination and photocarrier excitation processes in the heterostructures mainly originate from the pristine structure and the stacking faults in hBN. Our work provides a pathway toward efficient DUV light emitting and detection devices based on hBN.