Native and hydrogen-plasma induced shallow traps in hydrothermally grown ZnO crystals have been investigated by charge-based deep level transient spectroscopy (Q-DLTS), photoluminescence and cathodoluminescence microanalysis. The as-grown ZnO exhibits a trap state at 23 meV, while H-doped ZnO produced by plasma doping shows two levels at 22 meV and 11 meV below the conduction band. As-grown ZnO displays the expected thermal decay of bound excitons with increasing temperature from 7 K, while we observed an anomalous behaviour of the excitonic emission in H-doped ZnO, in which its intensity increases with increasing temperature in the range 140-300 K. Based on a multitude of optical results, a qualitative model is developed which explains the Y line structural defects, which act as an electron trap with an activation energy of 11 meV, being responsible for the anomalous temperature-dependent cathodoluminescence of H-doped ZnO.
@article{arxiv.1506.07217,
title = {Shallow carrier traps in hydrothermal ZnO crystals},
author = {C. Ton-That and L. L. C. Lem and M. R. Phillips and F. Reisdorffer and J. Mevellec and T. -P. Nguyen and C. Nenstiel and A. Hoffmann},
journal= {arXiv preprint arXiv:1506.07217},
year = {2015}
}