Hybrid density functional study of band alignment in ZnO/GaN and ZnO/(Ga1-xZnx)(N1-xOx)/GaN heterostructures

TL;DR

This study uses hybrid density functional calculations to analyze the band alignment and optical properties of ZnO/GaN heterostructures, revealing the potential for improved solar cell performance.

Contribution

It provides accurate band alignment data using hybrid functionals and explores a novel core-shell solar cell model based on these heterostructures.

Findings

(Ga1-xZnx)(N1-xOx) has a direct band gap of about 2.608 eV

The solid solution forms type-II band alignment with host materials

Hybrid functional calculations improve band gap and offset estimations

Abstract

The band alignment in ZnO/GaN and related heterostructures are crucial for the uses in solar harvesting technology. Here, we report our density functional calculations of the band alignment and optical properties of ZnO/GaN and ZnO/(Ga1-xZnx)(N1-xOx)/GaN heterostructures using a Heyd-Scuseria-Ernzerhof (HSE) hybrid functional. We found that the conventional GGA functionals underestimate not only the band gap but also the band offset of these heterostructures. Using the hybrid functional calculations, we show that the (Ga1-xZnx)(N1-xOx) solid solution has a direct band gap of about 2.608 eV, in good agreement with the experimental data. More importantly, this solid solution forms type-II band alignment with the host materials. A GaN/(Ga1-xZnx)(N1-xOx)/ZnO core-shell solar cell model is presented to improve the visible light adsorption ability and carrier collection efficiency.