The influence of whole boule annealing on the properties of semi-insulating indium phosphide

We have examined the effects of whole boule annealing on the properties of Fe-doped InP crystals grows by the Liquid Encapsulated Czochralski (LEC) process. The crystals were annealed at 750°C-950°C for periods of 6-24 hours. A polarized infrared macrograph system showed that annealing was effective in reducing the residual stress in the crystals. Higher temperatures were more effective in stress reduction. A balance between time and temperature must be considered to optimize the electrical properties. Electrical measurements by the van der Pauw technique showed that both resistivity and mobility were increased and more uniform after annealing at 950°C for 6 hours. Low temperature FTIR analysis of samples from the ingots annealed at 850°C for 6 hours showed that the concentration of the V_In-H₄ complex was uniformly distributed throughout the InP at a level of approximately 1.6×10¹⁵/cm³