  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.
