Band bending and field penetration on surfaces of ultrawide band gap semiconductors: Diamond and aluminum nitride

Abstract

Theoretical calculations were performed to study band bending and field penetration on surfaces of ultrawide band gap semiconductors in a negative field. The band bending was most prominent in the p-type materials with the surface potential of −4.85 eV for diamond and −5.53 eV for AlN at −20 V/μm and 400 K. The space charge region was terminated within a few microns in diamond and a few tens of microns in AlN. An appreciable penetrating field existed in the space charge region of p-type materials with a field strength of 2 to 3 V/μm for diamond and 0.2 to 0.3 V/μm for AlN. For the intrinsic and n-type (N doped) cases, the potential dropped very slowly from the surface to the bulk region while the field dropped very quickly within 0.1 μm. It was also found that the effective electron affinity was negative for p-type materials and positive for n-type materials. The characteristics of field emission from ultrawide band gap semiconductors according to our calculated results were also discussed.