In-situ monitoring of surface stoichiometry and growth kinetics study of GaN (0001) in MOVPE by spectroscopic ellipsometry

GaN surface stoichiometry and growth kinetics in MOVPE were studied by insi tu spectroscopic ellipsometry. The effect of MOVPE conditions on both the s urface stoichiometry and growth kinetics was investigated. The surface stoi chiometry, such as N-rich, Ga-rich and Ga-excess surfaces, was monitored, a nd was drastically changed by the variation of the NH, partial pressure. Wh en the TMG supply was interrupted during the growth, the layer-by-layer dec omposition/re-evaporation was observed in H-2/NH3 ambient. The decompositio n rate was measured as a function of the NH3 flow rate at the conventional epilayer growth temperatures (1050-1140 degreesC). The decomposition rate w as decreased with the increase in the N coverage on the GaN surface. It was found that the surface stoichiometry is a very important parameter for the control of the MOVPE growth kinetics.