Enhancing the intrinsic p-type conductivity of the ultra-wide bandgap Ga2O3 semiconductor

Abstract

While there are several n-type transparent semiconductor oxides (TSO) for optoelectronic applications (e.g. LEDs, solar cells or display TFTs), their required p-type counterpart oxides are known to be more challenging. At this time, the n-type TSO with the largest bandgap (∼5 eV) is Ga₂O₃ that holds the promise of extending the light transparency further into the deep ultraviolet. In this work, it is demonstrated that strongly compensated Ga₂O₃ is also an intrinsic (or native) p-type TSO with the largest bandgap for any reported p-type TSO (e.g. NiO, SnO, delafossites, oxychalcogenides). The achievement of hole mobility in excess of 10 cm² V⁻¹ s⁻¹ and (high temperature) free hole concentrations in the ∼10¹⁷ cm⁻³ range challenges the current thinking about achieving p-type conductivity in Ga₂O₃ being “out of the question”. The results presented in this paper therefore further clarify that p-type Ga₂O₃ is possible, although more research must be conducted to determine what are the real prospects for Ga₂O₃ solar blind bipolar optoelectronics and ultra-high power electronics based on p–n homojunctions.