THE EFFECT OF PRESSURE AND TEMPERATURE ON THE EFFECTIVE MASS AND ENERGY GAP OF GaAs

Abstract

Abstract : The report describes the results of an investigation of the effect of pressure and temperature on the energy gap and electron effective mass of GaAs. For this material, the applicability of the zero temperature Kane k.p theory at finite temperature was quantitatively tested by measuring the Faraday rotation as a function of pressure and temperature. The quantitative comparison of experimentally determined masses with theory required three subsidiary measurements: (1) the pressure change of energy gap of GaAs was found to be dE sub g/dP = (1.17 = .03).10 to the minus 5th power eV/bar; (2) the long wavelength pressure change of refractive index of GaAs was found to be (1/n)(dn/ dP) = - (7.0 = 0.5).10 to the minus 7th power (1/bar); and (3) the long wavelength temperature change of refractive index of GaAs was confirmed to be (1/n)(dn/dT) = (4.5 = 0.5).10 to the minus 5th power (1/K). The results of measurements on three n-type samples of GaAs as a function of temperature and pressure show that the data were fitted best by using the Kane k.p theory at finite temperature with an energy gap corrected from O K by accounting only for lattice expansion, rather than the experimentally determined optical energy gap which may be considered to have an implicit temperature dependence due to lattice expansion and an explicit temperature dependence.