Spectral shape analysis of ultraviolet luminescence in \textit{n}-type ZnO:Ga

TL;DR

This paper investigates the optical properties of n-type Ga-doped ZnO thin films, revealing broad and asymmetrical photoluminescence bands at room temperature, explained by a vibronic model involving phonon replicas.

Contribution

It introduces a vibronic model to explain the broadening and asymmetry of the near-band edge photoluminescence in Ga-doped ZnO, which previous potential fluctuation models could not fully account for.

Findings

Observation of intense room-temperature PL in the NBE region

Identification of broad, asymmetrical PL bands

Development of a vibronic model involving phonon replicas

Abstract

Thin films of laser molecular-beam epitaxy grown \textit{n}-type Ga-doped ZnO were investigated with respect to their optical properties. Intense room-temperature photoluminescence (PL) in the near-band edge (NBE) region was observed. Moreover, its broadening of PL band was significantly larger than predicted by theoretical results modeled in terms of potential fluctuations caused by the random distribution of donor impurities. In addition, the lineshape was rather asymmetrical. To explain these features of the NBE bands, a vibronic model was developed accounting for contributions from a series of phonon replicas.