Deep-UV Light-Emitting Based on the hBN:S/hBN: Mg Homojunction

A hexagonal boron nitride (hBN) based p-n homo-junction is expected to demonstrate a great potential for being fabricated into an emitter (either light-emitting diode or laser diode) in the deep-UV spectral region. However, it remains a great challenge to achieve n-type conductive hBN. Herein, n-type hBN is obtained by means of doping sulfur into hBN. The structure and the electric properties of S-doped hBN is studied via density functional theory, indicating that the orbital coupling between S 3p and B 2p orbital introduces shallow donor energy levels. The S atoms in the multilayer structure demonstrate enhanced electron delocalization compared with its mono-layer counterpart, suggesting that multilayer hBN:S is more inclined to be n-type conductive than its mono-layer counterpart. Experimentally, a multilayer hBN:S sample is successfully grown on sapphire substrates, where the S content, up to 1.21%, is obtained. The hBN:S film shows an in-plane current of 1.6 nA using Ti as ohmic contact and 8.4 nA using Ni as Schottky contact, respectively. The donor level induced by the S atoms is located at 0.349 eV below the CBM. Finally, a vertically-stacked n-hBN/p-hBN (hBN:S/hBN: Mg) structured junction is grown, and demonstrating a promise for being fabricated into a deep-UV emitter.