Compensation of CdTe by Doping With Gallium

Semi‐insulating CdTe single crystals doped with Ga were grown from the vapour phase by the modified Markov technique MMT. The study of the resistivity map in the cross‐sections cut a long the growth direction has been performed. The compensation phenomenon is analysed in the framework of the three levels Fermi‐statistic model. It is shown that a semi‐insulation behaviour throughout the ingot is due to the compensation of shallow impurities by the deep level. From the low ‐temperature photolum inescence spectra it was concluded that shallow donors (Ga_Cd) are partly compensated by (Ga_Cd‐V_Cd)^‐and (Ga_Cd‐Cd_Te) complexes and by residual acceptors (Na_Cd, Cu_Cd) . The microscopic structure of (Ga_Cd‐Cd_Te) complexis proposed based on the value of its local phonon mode and the growth conditions. A native defect like Te_Cd which has a deep level near the middle‐band‐gap is suppose to give a stable compensation and a tolerance for variation in shallow impurity concentrations.