Photoelectric and kinetic properties of PbTe(Ga) films

The photoelectric and kinetic properties of n-PbTe(Ga) films prepare don the BaF2 and Si substrates by hot wall epitaxy technique have been investigated in the temperature T interval 4.2 divided by 300 K. The photoelectric measurements show that all photosensitive samples may be divided into two groups characterized by positive and negative photosensitivity to IR-illumination at temperatures close to 4.2 K. The kinetics of positively photosensitive films is found to be similar to the kinetics of the bulk n-PbTe(Ga) single crystals of high resistance. The photoresponse of negatively photosensitive films appears to be composed from two parts. They are the dominant negative photosensitivity and a positive photoconductivity signal characterized by significantly faster kinetics. The experimental result are discussed in terms of DX-like behavior of the impurity centers.