Two‐Dimensional Carrier Gas at Diamond and Cubic Boron Nitride (111) Interface: Role of Interfacial Bonding and Defects

Diamond and cubic boron nitride (c‐BN) are promising ultrawide‐bandgap semiconductors for next‐generation high‐power and high‐frequency devices. Enabling these devices needs better understanding of interface electronic structure. Here, we investigate the effects of interfacial bonding and antisite point defects on the formation of two‐dimensional (2D) carrier gases at (111) diamond/c‐BN interfaces using hybrid density functional theory. c‐BN can be B‐ or N‐terminated. For each termination type, we identify two distinct interfacial bonding configurations, where a B (or N) atom is bonded to either one or three C atoms, resulting in four bonding types. Our results show that electron‐deficient C−B and electron‐rich C−N interfacial bonds result in 2D hole gas and 2D electron gas, respectively. Configurations with B (or N) bonded to three C atoms exhibit three times higher carrier density (1.3310 ) than those bonded to one C atom (4.4410 ). Furthermore, ‐type and ‐type antisite defects can stabilize C−B and C−N bonded interfaces, respectively, while reducing carrier density. Nevertheless, the carrier density remains high () even with these defects. This work may guide the engineering of diamond/c‐BN interfaces with tunable carrier densities for ‐ or ‐type conduction.