ABSTRACT
The structural perfection, surface state, electrical parameters, EL2 concentration and content of important residual impurities (C, B, O) of LEC GaAs single crystals in dependence on the argon pressure between 0.1 and 4.0 MPa have been investigated sytematically. Whereas at pressures > 1.0 MPa the gallium droplets at the crystal periphery disappear completely, the etch pit density, dislocation cell boundaries and EL2 concentration increase with pressure. The incorporated carbon content and the electrical resistivity decrease with increasing pressure, especially, in the region between 0.2 and 1.0 MPa very sensitively. A parallel behaviour has been found for boron. The oxygen concentration behaves opposite to carbon.
