Low dislocation density Si-doped GaAs single crystal grown by the vapor-pressure-controlled Czochralski method

Si-doped GaAs substrates have been widely used for optical devices. Recently, as the device fabrication process has changed, larger diameter substrates can be used. Almost dislocation-free Si-doped GaAs crystals of 75 mm diameter, which are suitable for the fabrication of optical devices, have been successfully grown using our vapor-pressure-controlled Czochralski (VCZ) method. The generation of slip dislocations could be suppressed and the growth of the dislocation-free crystal was achieved by decreasing the thickness of B2O3. The VCZ crystals contained a large amount of unintentionally doped boron (B) of about 10(18) cm(-3). By comparing the electrical data of the VCZ crystals with those of the gradient freeze (GF) crystal free from B, it is found that B accepters decrease the intrinsic compensation ratio ([Si-As]/[Si-Ga]).