Growth temperature dependence of EL2 concentration in GaAs grown by metalorganic vapor-phase epitaxy using tertiarybutylarsine

The EL2 concentration in GaAs grown by metalorganic vapor-phase epitaxy (MOVPE) using tertiarybutylarsine (tBAs) was measured by deep-level transient spectroscopy. EL2 concentration decreases monotonically with increasing growth temperature. Taking the origin of EL2 into consideration, we discuss the growth mechanisms of MOVPE using tBAs. The EL2 concentration is affected by the incorporation of excess As into the crystal, and, therefore, depends on the kind of reactant on the surface. We propose a model in which the reactant on the surface changes from As2H2 to As2 with increasing temperature. The temperature dependence of EL2 concentration is explained by our model where As2 dissociates into atomic As on the surface and As2H2 gives excess As in the crystal.