Red Luminescence in H-doped beta-Ga2O3

TL;DR

This study demonstrates that hydrogen doping in beta-Ga2O3 induces a distinct red luminescence at 1.9 eV, linked to H-related defect complexes, and significantly enhances electrical conductivity.

Contribution

It provides new insights into the optical and electrical effects of hydrogen incorporation in beta-Ga2O3, identifying specific defect complexes responsible for red luminescence.

Findings

Hydrogen doping creates a 1.9 eV red luminescence band.

Electrical conductivity increases by an order of magnitude with H doping.

H-related defect complexes act as shallow donors and recombination centers.

Abstract

The effects of hydrogen incorporation into beta-Ga2O3 thin films have been investigated by chemical, electrical and optical characterization techniques. Hydrogen incorporation was achieved by remote plasma doping without any structural alterations of the film; however, X-ray photoemission reveals major changes in the oxygen chemical environment. Depth-resolved cathodoluminescence (CL) reveals that the near-surface region of the H-doped Ga2O3 film exhibits a distinct red luminescence (RL) band at 1.9 eV. The emergence of the H-related RL band is accompanied by an enhancement in the electrical conductivity of the film by an order of magnitude. Temperature-resolved CL points to the formation of abundant H-related donors with a binding energy of 28 +/- 4 meV. The RL emission is attributed to shallow donor-deep acceptor pair recombination, where the acceptor is a VGa-H complex and the shallow donor is interstitial H. The binding energy of the VGa-H complex, based on our experimental considerations, is consistent with the computational results by Varley et al [J. Phys.: Condens. Matter, 23, 334212, 2011].