We propose to use the 'double-crucible' technique to grow semi-insulating gallium arsenide crystals which are of uniform stoichiometric composition from seed to tail, and are free from arsenic precipitaties. The nature of the phase diagram suggests that this approach should be very effective in GaAs, and the Principal Investigator has already established to use of the double crucible method in Liquid Encapsulated Czochralski crystal growth.