The kinetics of the electrical activation of hydrogenated As acceptors in metal-organic vapor-phase epitaxially grown layers were studied for As dopant contents which ranged from 8 x 1016 to 1020/cm3. Annealing (1s to 1h) was performed at temperatures of between 150 and 550C. The hole concentration in annealed samples was determined by using Van der Pauw's method, and the As-H pair concentration was deduced from the intensity of the absorption line at 2022/cm; as detected using Fourier transform spectrometry. Annealing, for up to 60s, revealed a continuous increase in hole concentration (1017 to 2 x 1017/cm3 at 500C) with time and temperature. The concentration of As-H pairs decreased at the same time, but at a higher rate. Longer annealing times usually led to a decrease in hole concentration, while the As-H pair concentration either continued to fall, or recovered; depending upon the level of As doping. The results were explained in terms of a theoretical analysis which took account of processes such as the dissociation-recombination of impurity-H pairs, electronic ionization of As impurities, and electrical compensation due to the formation of As-vacancy complexes. It was proposed that As ionization occurred in 2 steps. The first corresponded to a thermally activated conversion process, while the second involved hole emission. The microscopic nature of the intermediate neutral impurity state was not known.

L.Svob, Y.Marfaing, B.Clerjaud, D.Côte, A.Lebkiri, R.Druilhe, A.Lusson, C.Grattepain: Semiconductor Science and Technology, 1998, 13[1], 79-85