A thermodynamic model for determining pressure and temperature effects on the bandgap energies and other properties of some semiconductors
Semiconductor bandgap energies are shown to be equal to the difference between the sum of the standard chemical potentials of free electrons and holes and standard chemical potential of the recombined electron-hole pairs when equilibrium occurs at a given temperature and pressure. The decrease in the bandgap energies of diamond semiconductors with increasing temperature is shown to be caused by the interaction of the free electrons, holes and recombined electron-hole pairs with lattice phonons and linear expansion of the lattice constant. The determined bandgap energies and other intrinsic properties of nondegenerate GaAs are found to be in excellent agreement with experimental data as a function of temperature and pressure. The proposed model is also shown to be useful in determining the effects of temperature and pressure on the intrinsic properties of epilayers and substrate in the metal-semiconductor junctions and heterojunctions.