GaZn-VZn acceptor complex defect in Ga-doped ZnO

TL;DR

This study identifies and characterizes the (GaZn-VZn) acceptor complex defect in Ga-doped ZnO, revealing its role in compensation, energy levels, and optical properties, which could enable new defect-engineered optical applications.

Contribution

It provides a systematic experimental and theoretical analysis of the (GaZn-VZn) complex defect in Ga-doped ZnO, including its binding energy, energy levels, and optical emission properties.

Findings

High density of (GaZn-VZn) defect acts as a major compensator.

Binding energy (~0.78 eV) matches electrical activation energy (~0.82 eV).

Optical emission at ~650 nm with 10-20 ns lifetime.

Abstract

Identification of complex defect has been a long-sought-after physics problem for controlling the defect population and engineering the useful properties in wide bandgap oxide semiconductors. Here we report a systematic study of (GaZn-VZn)- acceptor complex defect via zinc self-diffusion in Ga-doped ZnO isotopic heterostructures, which were conceived and prepared with delicately controlled growth conditions. The secondary ion mass spectrometry and temperature-dependent Hall-effect measurements reveal that a high density of controllable (GaZn-VZn)- is the predominant compensating defect in Ga-doped ZnO. The binding energy of this complex defect obtained from zinc self-diffusion experiments (~0.78 eV) well matches the electrical activation energy derived from the temperature-dependent electrical measurements (~0.82 eV). The compensation ratios were quantitatively calculated by energetic analysis and scattering process to further validate the compensation effect of (GaZn-VZn)- complex in Ga-doped ZnO. Meanwhile, its energy level structure was suggested based on the photoluminescence spectra, and the lifetime was achieved from the time-resolved photoluminescence measurements. The electron transitions between the (GaZn-VZn)- complex defect levels emit the light at ~650 nm with a lifetime of 10-20 nanoseconds. These findings may greatly pave the way towards novel complex defects-derived optical applications.