Materials Chemistry and Physics, 9 (1983) 307- 3 14 307 Si-DOPING EFFECT ON ELECTRICAL PROPERTIES OF LEC-GaAs CRYSTALS R.FORNARI, L.ZANOTTI and G.ZUCCALLI C.N.R., MASPEC Institute, via Chiavari 18/A, 43100 Parma (Italy) ABSTRACT The results of electrical measurements carried out on several GaAs samples having different silicon doping are reported and di- scussed, taking into account the main sources of inhomogeneities in LEC grown crystals. Both axial and radial free carrier distribution were studied. A vaZue for the electron concentration segregation coefficient higher than those reported in earlier studies was found. The compensation ratio was also derived from mobility studies for different doping levels. It must be stressed that for an elec- tron concentration above 10 17 3 /cm the value of the compensation ratio is in the 0.4 to 0.6 range. The presence of 'one acceptor' is considered in order to explain the high compensation. INTRODUCTION Silicon doping is commonly used to prepare n-type GaAs. The am- photeric behaviour of silicon in GaAs has aZready been studied [l-3] and the intrinsic compensation ratio (siAs/si Ga) was found to be 0.15 to 0.30 in GaAs crystals grown by the Liquid Encapsulation Czochralski (LECI technique [2,4] ,th e site distribution being de- pendent upon the presence of other impurities and vacancies in both gallium and arsenic sublattices. Because of this compensation the electron concentration differs from the silicon concentration. 0254-0584/83/US $3.00 0 Elsevier Sequoia/Printed inThe Netherlands