Energy Gap Of GaAs Research Articles

Nonhydrogenic Exciton and Energy Gap of GaAs

The free-exciton series $n=1,2,3$ in high-purity GaAs has been observed in photoluminescence and photoconductivity. The $n=1$ peak shifts upon changing the excitation level because of free-carrier screening. Anisotropy and exchange effects as well as two valence bands must be included to interpret the series spectrum of this Wannier-like exciton. New values are derived for the band gap at 1.6 K (${E}_{g}=1.5189\ifmmode\pm\else\textpm\fi{}0.0001$ eV) and for the $n=1$ excitonic binding energy [${E}_{X}(1s)=3.77\ifmmode\pm\else\textpm\fi{}0.05$ meV].

Temperature dependence of the energy gap in GaAs

Temperature dependence of the energy gap in GaAs

Temperature Dependence of the Energy Gap in GaAs

We show that a recent psuedopotential calculation overestimates the temperature dependence of the band gap in GaAs. We also calculate the individual contributions of the pseudopotential coefficients to the shift with temperature and find that the theoretical shift is dominated by ${V}_{11}^{s}$. Hence the disagreement between theory and experiment may result from the arbitrary truncation of the pseudopotential for ${G}^{2}>11$.

Temperature Dependence of the Energy Gap in GaAs and GaP

Absorption measurements from 300°–973°K for GaAs and to 1273°K for GaP were made in order to determine the energy gap Eg of these materials at high temperatures. These data, together with previously published results, show that the energy-gap width may be represented by a simple expression for all temperatures. As a function of the absolute temperature T, the direct gap in GaAs is given by Eg=1.522−5.8×10−4T2 / (T+300) eV, and the indirect gap in GaP is given by Eg=2.338−6.2×10−4T2 / (T+460) eV. The general form of the expression for the energy gap is Eg=Eg(0)−aT2 / (T+β), where Eg(0) is the energy gap at 0°K, β is approximately the 0°K Debye temperature, and a is an empirical constant.

Effect of Pressure on the Spontaneous and Stimulated Emission from GaAs

The spontaneous and stimulated emission from diodes of GaAs has been studied at room and liquid-nitrogen temperatures as a function of hydrostatic pressure up to 8 kbar. The displacement with pressure of the spontaneous emission peak is +1.1\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}5}$ eV/bar which agrees with the pressure coefficient of the energy gap in GaAs and of analogous energy gaps in group 3-5 compounds. The constancy of the linewidth with pressure suggests that an electron distribution in the conduction band is not responsible for the linewidth. Changes with pressure in the energy and intensity of lower energy emission lines provide information on the nature of the electronic transitions involved. Mode spikes of stimulated emission change energy with pressure as the crystal dimensions and the refractive index decrease, and these changes have been correlated with subsidiary measurements of the pressure coefficient of the index found from interference fringes. Suggestions for further informative measurements on other materials are made.