INHOMOGENEITY IN A SEMIINSULATING INDIUM-PHOSPHIDE INGOT

A whole semi-insulating iron-doped indium phosphide ingot, grown by the conventional Czochralski growth method, is investigated by cartographical methods. Experiments are made on samples cut along the <001> growth axis: inhomogeneities are clearly evidenced by scanning photoluminescence measurements at 300 K. The decreasing in the PL intensity is found to follow the iron concentration increase. The scattering laser tomography technique is also applied to this ingot. The number of the defects thus revealed is found to decrease from the head to the tail of the ingot. On the opposite, the size of the defects increases towards the tail.