First principles calculation of polarization induced interfacial charges in GaN/AlN heterostructures

TL;DR

This paper introduces a new first-principles based method to accurately calculate polarization-induced interfacial charges in GaN/AlN heterostructures, validated against experimental data and bulk polarization constants.

Contribution

A novel approach combining classical electrostatics with first-principles band diagrams to determine interfacial charges in semiconductor heterostructures.

Findings

Calculated interfacial charge matches experimental values

Electric fields are independent of exchange-correlation functionals

Bulk polarization constants are valid for ultrathin films

Abstract

We propose a new method to calculate polarization induced interfacial charges in semiconductor heterostructures using classical electrostatics applied to real-space band diagrams from first principles calculations and apply it to GaN/AlN heterostructures with ultrathin AlN layers (4-6 monolayers). We show that the calculated electric fields and interfacial charges are independent of the exchange-correlation functionals used (local-density approximation and hybrid functionals). We also find the calculated interfacial charge of (6.8 +/- 0.4) x 10^13 cm-2 to be in excellent agreement with experiments and the value of 6.58 x 10^13 cm-2 calculated from bulk polarization constants, validating the use of bulk constants even for very thin films.