Metastable-like behaviour of a sputter deposition-induced electron trap in n-GaN

Abstract

We show that a deep level, the ES1, introduced in n-GaN by sputter-deposition of gold Schottky contacts exhibits metastable-like behaviour during temperature cycling between 55 and 250K. The ES1 has an energy level 0.22±0.02eV below the conduction band. We provide some evidence that indicates that the defect responsible for the ES1 has a second energy level, the ES1∗, and that the metastable behaviour of the ES1 may be due to negative-U ordering of these two energy levels. Furthermore, field effect measurements indicate that the ES1 level has a donor character, while the ES1∗ level is probably an acceptor.