The comparison of the results of chemical composition, crystal structure, electronic properties and infrared photoconductivity investigations of PbTe Si and PbTe SiO2 Si heterostructures doped with Ga atoms by two different techniques is presented in this work. One of these techniques is principally based on the vapour-phase doping procedure of PbTe Si and PbTe SiO2 Si heterostructures, which were previously formed by the modified "hot wall" technique. The second method of PbTe(Ga) Si and PbTe(Ga), SiO2 Si heterostructure preparation is based upon the fabrication of lead telluride films, which have been doped with Ga atoms in the layer condensation process directly, The lattice parameter and charge carrier density evolutions with the Ga impurity concentration show principally the different character of PbTe(Ga) Si films prepared by these techniques. It has been proposed that complicated amphoteric (donor or acceptor) behaviour of Ga atoms may be explained by different mechanisms of substitution or implantation of 0impurity atoms in the crystal structure of lead telluride. (C) 2002 Elsevier Science B.V. All rights reserved.