The Average Heat of Atomization and the Properties of Semiconductors

Abstract

In correlating the physical properties of known semiconductors and predicting the properties of new ones a number of parameters have been employed with varying degrees of success. Typical parameters have been the electronegativity difference, the heats of formation, the average principal quantum number and the atomic or ionic radii. All such parameters are related to the binding energy of semiconductors and consequently to properties such as their energy gap. In the present study the cohesive energy was considered as the most basic parameter for analyzing the characteristics of semiconductors. In elemental semiconductors the cohesive energy is given by the energy of atomization and is known in all instances. In contrast, the cohesive energy of compound semiconductors is not generally known. A simple method of calculating the heats of atomization of compounds from the heats of atomization of the elements was developed. The resulting “average heats of atomization” do not contain the contribution of the heats of formation but they can serve essentially as the cohesive energies particularly in predominantly covalent semiconductors, where the heats of formation represent only a small fraction of the cohesive energy. The “average heats of atomization” were found to be very successful in correlating the properties of a number of groups of semiconductor compounds including the vitreous semiconductors and the limits of stability of various structures among semiconductor compounds.