HYDROGEN-RELATED METASTABLE DEFECTS IN PASSIVATED N-TYPE GAAS GROWN BY METAL-ORGANIC VAPOR-PHASE EPITAXY

Undoped n-type GaAs grown by metal-organic vapor-phase epitaxy is exposed to a hydrogen or a deuterium plasma. Two dominant deep levels, having energies E(c) - 0.2 eV and E(c) - 0.57 eV, are formed after hydrogenation. Their depths into the material correspond directly with the depth to which the shallow donors have been passivated. Furthermore, isothermal annealing measurements under zero- and reverse-bias conditions reveal that the two levels are metastable. The transformations from one configuration to the other obey first-order kinetics, with the following transformation rates: nu-1(T) = 1.2 x 10(8) exp[(-0.82 eV)/kT] and nu-2(T) = 8.0 x 10(10) exp[(-0.95 eV)/kT]. We attribute the deep levels to the formation of a hydrogen-related complex. The new hydrogen complex is found to be more stable than the shallow donor-hydrogen complex.