By using deep-level transient spectroscopy, deep centers were characterized in unintentionally doped n-type samples grown by metal-organic chemical vapor deposition and subjected to inductively coupled plasma reactive ion etching. At least 6 deep level transient spectroscopy traps existed in the control sample: A1 (~0.90eV), Ax (~0.72eV), B (0.61eV), C1 (0.44eV), D (0.25eV) and E1 (0.17eV); with B predominating. As the etching bias-voltage was increased from –50 to –150V, trap D increased strongly and became dominant while traps A1, C (0.34eV) and E1 increased at a lower rate. Trap B was nearly unchanged. Previous electron-irradiation studies were consistent with the E1 traps being N-vacancy related. It was suggested that the D traps were also N-vacancy related, except that they were in the region of dislocations.

Plasma-Etching-Enhanced Deep Centers in n-GaN Grown by Metalorganic Chemical-Vapor Deposition. Z.Q.Fang, D.C.Look, X.L.Wang, J.Han, F.A.Khan, I.Adesida: Applied Physics Letters, 2003, 82[10], 1562-4