Growth and properties of very large crystals of semi-insulating gallium arsenide

A modified liquid encapsulated Czochralski (LEC) process has been developed which yields completely single crystals 22 kg in weight, 110 mm diameter and 435 mm parallel length. These crystals will yield up to 375 wafer/ingot compared with the 50-80 wafers typical of the current 8 kg process. This process moves the production of GaAs substrates from a research and development operation to a genuine production process with significant improvements in economy, for both substrate and device manufacturers. The key to the process is the control of melt/solid interface shape by modification of the thermal geometry of the MRSL 15/25 puller, using a simple single heater system. Uniformity of electrical properties was maintained over the length of these long crystals.