Heterostructures on Si substrates formed from AIVBVI semiconductors doped with III A Periodic system group metals will continue to attract a widespread attention both for their fundamental electronic properties and for the applications in infrared (IR) optoelectronic. It is well known that the way to increase the charge carrier density in PbTe, which is needed for photovoltaic IR detectors, is doping with In and Tl. For the preparation of PbTe/Si heterostructures the modified HWE technique has been used. The chemical quantitative composition, X-ray patterns, SEM results, and charge carrier densities of PbTe/Si films, which had been fabricated under different experimental conditions, have been compared in this work. For the first time in this work the amphoteric (donor or acceptor) behaviour of In impurity atoms has been analyzed with respect of Te atoms concentration. It has been detected that at 77 K the high values of charge carrier density of about 1018 - 1019 cm-3, which are needed for photovoltaic IR detectors, appear only in n-type Pb1-yIn
Te/Si films with, if these layers were characterized with little deficiency of Te atoms with regards to stoichiometric relation. If 0.001 < yIn < 0.009, the electron density shows the weak dependence upon the concentration of In atoms. On the contrary, in p-type Pb1-yIn
Te/Si films with little excess of Te atoms the hole densities decline fast with increase in In concentration at yIn > 0.007. For explanation of amphoteric behaviour of In the model based upon the different charge states of impurity atoms has been proposed within frameworks of crystal - quasichemical approximation.