The high‐pressure liquid encapsulated Czochralski growth of indium lattice‐hardened GaAs, from 3 kg melts, has resulted in low‐dislocation, large‐diameter crystals which exhibit thermally stable, semi‐insulating properties. Post‐growth boule annealing is found to be an effective stress‐relief treatment, which assures high wafer yields and extremely uniform electrical properties. Observed reductions in dislocation density for mid 1019cm−3In‐doped GaAs substrates indicate an apparent 28‐fold increase in the critically resolved shear stress of this material over undoped GaAs near the melting point. Polished substrates obtained from these crystals exhibit very little subsurface damage, approaching high‐quality silicon wafers in this respect.