Electrical Properties of Single Crystals and Thin Films of PbSe and PbTe

A comparison was made of the electrical properties of single crystals and subsequently formed thin films of PbTe and PbSe. Hall constants and resistivities were measured as a function of temperature from 300° to 77°K. Films were formed and measured without exposure to air. Regardless of whether the original crystal was $n$ or $p$ type, all films were $n$ type, having carrier concentrations within the same order of magnitude for most cases. This observation was attributed to a limited amount of dissociation during evaporation, resulting in an inhomogeneous distribution of Te (or Se) agglomerates throughout the film. Room temperature mobilities in annelated films were about $\frac{1}{5}$ that of the bulk values. In general carrier mobilities in films were markedly affected by substrate temperature during film formation, subsequent annealing, and limited oxygenation.