A study on splitting of the valence band for a AgInS[sub 2]/GaAs epilayer using photocurrent measurement.

The chalcopyrite AglnS[sub 2] epilayers were grown on the GaAs substrate by using a hot-wall epitaxy (HWE) method. The temperature dependence of the energy band gap of the AgInS[sub 2] obtained from the absorption spectra was well described by the Varshni's relation, Eg(T)=2.1365 eV-(9.89 × 10[sup -3] eV)T[sup 2]/(2930 + T). In addition, we obtained the free exciton binding energy, 0.1115 eV, for the chalcopyrite AglnS[sub 2]/GaAs by using Shay's result. The crystal field and the spin-orbit splitting energies for the valence band of the AglnS[sub 2] have been estimated to be 0.1541 eV and 0.0129 eV, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the A so definitely exists in the ... 5 states of the valence band of the AglnS[sub 2]/GaAs epilayer. The three photocurrent peaks observed at 10 K are ascribed to the A[sub 1-], B[sub -1], and C[sub -1]-exciton peaks for n = 1. Also, we obtained the A[sub ∞-] and B[sub ∞-] exciton peaks from the PC spectrum at 293 K. Therefore, we conclude that the peaks observed by the photocurrent measurement are the free exciton peaks or peaks due to band-to-band transitions. [ABSTRACT FROM AUTHOR]