Relationship between Carrier and Impurity Concentrations in Vapor-Epitaxial n-GaAs Crystals

Abstract

The relationship between the room-temperature carrier concentration n0 and the total impurity concentration NI is investigated in order to obtain some information on the natures of the residual impurities and the native crystal defects in epitaxial n-GaAs layers grown by the Ga/ASCl3/H2 method. The n0vsNI curves observed are compared with that calculated from the Rytova-Fistul' theory which considers thermo-dynamically the amphoteric impurity distribution in compound semiconductors. Both are in good agreement if some unknown parameters are reasonably adjusted. Preliminary check is also made on the effect of the arsenic partial pressure on the values of these parameters. From these results it is supposed that the electrically-active centers in epitaxial n-GaAs layers mainly come from amphoteric impurities and the arsenic vacancies also play a significant role as compensating acceptors.