Semi-insulating Fe-doped samples were annealed under various conditions, and were investigated by using Hall effect, extrinsic photo-current mapping, chemical etching and optical microscopic techniques. The resistivity was increased by all of the treatments; particularly in wafer-annealed InP. This result was attributed to strong losses of shallow donors. Marked differences existed between the structural properties of wafer and ingot -annealed material. Wafer annealing led to the rapid elimination of growth striations and decoration micro-defects, whereas ingot-annealed material retained these micro-defects; both along dislocations and in the matrix. The photo-current maps indicated that thermal treatments normally improve doping uniformity. The best uniformity was found for a long annealing time (more than 50h), while a slow cooling rate improved the mobility.

M.Avella, J.Jiménez, A.Alvarez, R.Fornari, E.Gilioli, A.Sentiri: Journal of Applied Physics, 1997, 82[8], 3836-45