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

TL;DR

This paper investigates the large polarization charge density at GaN/ScN interfaces due to polarization discontinuity, revealing potential for high-density electron or hole gases and applications in tunnel junctions and contacts.

Contribution

It demonstrates the significant polarization discontinuity at GaN/ScN interfaces and explores its implications for high-density carrier gases and device applications.

Findings

Polarization discontinuity of -1.358 C/m² at GaN/ScN interface

Potential for carrier densities up to 8.5×10¹⁴ cm⁻²

ScN's suitability for polarization-enhanced tunnel junctions

Abstract

Rocksalt 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 exihibts a large polarization discontinuity of $-$1.358 $\rm Cm^{-2}$. Interfaces between ScN and wurtzite III-nitrides will exhibit a high-density electron gas on the (000$\bar{1}$) GaN interface or a hole gas on the (0001) GaN interface, with carrier concentrations up to $8.5 \times 10^{14}$ cm$^{-2}$. The large polarization difference and small strain makes 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.