Abstract: In this paper, a study has been made of the compensation ratio (θ), the minority carrier diffusion length (L_p) and the dislocation density of Si-doped GaAs crystals grown by the horizontal Bridgman method. The study on compensation ratio shows that tie donor can be self-compensated through a defect equilibrium due to the formation of the Si_GaV_Ga complex, when the carrier concentration is greater than 10¹⁷cm^-3. Some relationships between L_p, dislocation density and θhave been found. The L_p decreases with the θ increasing and changes abruptly at around θ=0.3, while the θ found for dislocation-free and low dislocated crystals is greater than 0.38 with the carrier concentration in the range of 1~2×10¹⁸cm^-3. It may be suggested that the L_p and dislocation density are related to Si_GaV_Ga in some way, which is formed through the interaction between Si_Ga and V_Ga, and with V_Ga created in turn from Si and O, by the removal of Si from Ga sites.
In general, the θ could be used as a satisfactory guide to the quality of Si-doped GaAs crystals.