Helicon-wave-excited plasma nitridation of GaAs after short-time plasma oxidation for fabrication of damage-free GaN/GaAs interface

Short-time (5-30 min) and long-time (5-7 h) helicon-wave-excited (HWP) N-2- Ar plasma treatments of GaAs (100) substrates were performed after short-ti me inductively coupled (ICP) O-2-Ar plasma pretreatments, under two process ing conditions in which the plasma sheath widths were small and the largest in our plasma apparatus. The detrimental effects of Ar etching during proc essing, such as plasma-induced damage, could be reduced if the plasma sheat h width was larger For short-time HWP N-2-Ar plasma treatment with the smal l plasma-sheath width, the effective Schottky barrier height decreased and the reverse leakage current substantially increased with the plasma-exposur e lime, suggesting the introduction of a high density of the plasma-induced defect centers. On the other hand, the effective barrier height did not ch ange and the reverse leakage current decreased for the GaAs samples treated in HWP N-2-Ar plasma with the largest plasma-sheath width. Reasonably good MIS C-V characteristics were obtained fur the long-time HWP N-2-Ar plasma treatment with the largest sheath width.