RADIATION-INDUCED CARBON COMPLEXES IN GALLIUM-ARSENIDE

Gallium arsenide grown by the metallorganic chemical vapour deposition method and n-doped to various silicon concentrations was irradiated w ith reactor neutrons (1 MeV equivalent damage in silicon) in the fluen ce range 0 to 3 X 10(15) CM-2. Native defects, including carbon which is a residual impurity of the growth method, and those introduced by i rradiation, were characterized by photoluminescence (PL) and deep leve l transient spectroscopy (DLTS). In some samples with fixed doping val ue, the PL intensity of all the transitions, including that to the car bon impurity increases at low fluence levels before decreasing at high fluence. At higher fluences, the transition to the carbon impurity go es through other maxima. The carbon PL intensity versus fluence curve depends on initial doping. DLTS results reveal the removal of a trap E L12 at low fluences, but the introduction of other traps at higher flu ences. The defect introduction rates depend on fluence. We attribute t he variation in the carbon PL intensity to an interaction between the defects introduced by the irradiation and the carbon impurity.