Deep-level transient spectroscopy was used to study the electrical properties of defects which were introduced into epitaxial n-type material during sputter deposition. Four defects, ES1 to ES4, which were located at 0.22, 0.30, 0.40 and 0.45eV below the conduction band, were characterized. The ES4 defect appeared to have a band-like energy distribution. The ES1 defect, which was located at Ec - 0.22eV had a similar deep-level transient spectroscopy signature to that of the E and ER3 defects which were introduced into epitaxial GaN by high-energy electron and He-ion bombardment, respectively. The ES2 defect seemed to be the same as the EO2 defect in as-grown GaN; but its concentration strongly increased towards the surface. The ES3 and ES4 defects, with energy levels at Ec - 0.40 and Ec - 0.45eV, respectively, had not previously been observed in as-grown or bombarded material.

Sputter Deposition-Induced Electron Traps in Epitaxially Grown n-GaN. F.D.Auret, S.A.Goodman, F.K.Koschnick, J.M.Spaeth, B.Beaumont, P.Gibart: Applied Physics Letters, 1999, 74[15], 2173-5