Giant polarization charge density at lattice-matched GaN/ScN interfaces

Rock-salt ScN is a semiconductor with a small lattice mismatch to wurtzite GaN. Within the modern theory of polarization, ScN has a nonvanishing formal polarization along the [111] direction. As a result, we demonstrate that an interface between (0001) GaN and (111) ScN exhibits a large polarization discontinuity of −1.358 Cm−2. Interfaces between ScN and wurtzite III-nitrides will exhibit a high-density electron gas at the (0001¯) GaN interface or a hole gas at the (0001) GaN interface, with carrier concentrations up to 8.5×1014 cm−2. The large polarization difference and small strain make ScN a desirable choice for polarization-enhanced tunnel junctions within the III-nitride materials system. The large sheet carrier densities may also be useful for contacts or current spreading layers.