Crystal structure and electrical parameters of In-doped PbTe/Si films prepared by modified HWE technique

The chemical quantitative composition, crystal structure, and electrical properties, of In-doped PbTe/Si and PbTe/SiO2/Si films have been studied in this work. The modified hot wall technique has been used to prepare the PbTe<In>/Si heterostructures, which were doped with In during the condensation process directly. In this way, the Pb1-xInx (0.05less than or equal tox(ln)less than or equal to0.50) liquid alloys have been employed as the sources of indium and lead vapours coincidentally. By electron probe microanalysis and atomic absorption measurements, it has been established that the concentration of In atoms y(ln) varied from 0.0011 to 0.045 in these Pb(1-y)ln(y)Te films. The comparison of microstructural observations and XRD measurements allows to determine that phase constitution and real-crystal structure of these Pb1-yInyTe films depend upon the indium content y(ln) and the presence of intermediate SiO2 buffer layers. It has been found that formation of In solid solutions in lead telluride matrix revealed the PbTe-InTe and PbTe-ln(2)Te(3) pseudobinary systems. The results of X-ray diffraction show that the lattice parameter a(PbTe) of PbTe<ln>/Si and PbTe<ln>/SiO2/Si heterostructures is described by the non-monotone function and does not obey Vegard's law within the concentration interval 0.0011less than or equal toy(ln)less than or equal to0.045. It has been detected that at 77 K, the high values of charge carrier density of about 10(18)-10(19)cm(-3) appeared in p-type Pb(1-y)ln(y)Te/Si films within concentration interval 0.0022<y(ln)<0.0064. (C) 2003 Elsevier Science B.V. All rights reserved.