BEHAVIOR OF THE MIDGAP LEVEL EL2 IN VPE GaAs.

The effect of growth temperature, type of dopant and their concentration, and As/Ga ratio in the gas phase on the concentration of EL//2 in VPE GaAs have been investigated. The EL//2 concentration was found to increase with increasing As/Ga ratio in the gas phase. A slope of 2/3 has been obtained from a plot of EL2 plus C (where the C trap was first reported by Ozeki et al. ) against the As/Ga ratio in the gas phase on the basis of literature data and the result of the present investigation. In contradiction with Ozeki's observations, it has been found, however, that the EL2 concentration varies not only with the type of dopant but also with their concentration when the latter exceeds 10**1**6cm** minus **3 . Our experimental results are in good agreement with the model suggested in a previous paper, and therefore may be regarded as providing a strong support to the postulated antisite complex structure of the EL2 level.