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

Su-Beom Song,Jonghwan Kim,Hyeon-Woo Jeong,Sera Yang,So Young Kim,Sangho Yoon,Takashi Taniguchi,Gil-Ho Lee,Seung-Young Seo,Kenji Watanabe,Jun Sung Kim,Moon-Ho Jo,Soonyoung Cha

doi:10.1038/s41467-021-27524-w

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.

Highlights

Hexagonal boron nitride is a van der Waals semiconductor with a wide bandgap of ~ 5.96 eV
We demonstrate DUV electroluminescence and photocurrent generation in Van der Waals (vdW) heterostructures where a DUV photoactive layer of Hexagonal boron nitride (hBN) is vertically stacked between a pair of graphene electrodes
The photocurrent generation and electroluminescence processes in hBN vdW heterostructures are schematically illustrated in Fig. 1a, b

Summary

Introduction

Hexagonal boron nitride (hBN) is a van der Waals semiconductor with a wide bandgap of ~ 5.96 eV. Strong electric field from high bias voltages enables carrier injection from the electrodes to the hBN band edges by the Fowler-Nordheim tunneling mechanism, which leads to the radiation of prominent DUV electroluminescence lines.

Results

Conclusion