Plasma-etching-enhanced deep centers in n-GaN grown by metalorganic chemical-vapor deposition

By using deep-level transient spectroscopy (DLTS), deep centers have been characterized in unintentionally doped n-GaN samples grown by metalorganic chemical-vapor deposition and subjected to inductively coupled plasma reactive ion etching. At least six DLTS traps exist in the control sample: A(1) (similar to0.90 eV), A(x) (similar to0.72 eV), B (0.61 eV), C-1 (0.44 eV), D (0.25 eV), and E-1 (0.17 eV), with B dominant. Then, as the etching bias-voltage increases from -50 to -150 V, trap D increases strongly and becomes dominant, while traps A(1), C (0.34 eV), and E-1 increase at a slower rate. Trap B, on the other hand, is nearly unchanged. Previous electron-irradiation studies are consistent with the E-1 traps being N-vacancy related. It is likely that the D traps are also, except that they are in the regions of dislocations. (C) 2003 American Institute of Physics.