Abstract
The properties of the lead ohaloogenide group of semiconductors and more specifically of PbTe, have been investigated in order to predict, and control the growth of thin epitaxial films for use as thin film field effect transistors. The thermodynamic properties of binary compounds has been analysed in detail and used to explain the defect properties of PbTe and PbSe. The calculated pressure-temperature-composition (or P-T-x) phase diagram for PbTe was compared with "as grown" and annealed epitaxial film properties (grown on mica substrates) to discover whether films obeyed bulk thermodynamics. "As grown" films appear to be metastable, i.e. their composition, estimated from electrical properties, suggests that they lie outside the phase boundary at the substrate temperatures employed (200-300°C). Changes occur on annealing in vacuo which suggest that the films tend toward the thermodynamic equilibrium state represented, by the calculated bulk P-T-x phase diagram. An investigation of the electrical properties of ternary solid solutions of group IX elements with PbTe and PbSe has been carried out in the hope of producing an improved semiconductor material compared with PbTe and PbSe. A correlation of electrical properties with film structure, obtained from replication and transmission elctron microscopy, was attempted producing a number of useful and interesting conclusions.