The exciton energy spectrum in GaAs has been studied by photoluminescence and reflection. The photoluminescence was excited using a krypton laser (6471 Å). We observed for the first time the spectra for the excited states of the free exciton in GaAs and also the spectra for the ground states in zero field and in the field range from 12 to 40 kG. The value for the exciton binding energy was determined to be (4.20 ± 0.3) × ${10}^{-3\mathrm{}}$ eV from which the band-gap energy of 1.5195 ± 0.0005 eV has been deduced. The values for the Zeeman splitting factors for electron ($g$ factor) and hole ($\kappa$ parameter) were deduced from these measurements to be $g_c=-0.50\mathrm{}\pm 0.05$ and $\kappa =1.0\mathrm{}\pm 0.2$, respectively. A phenomenological description for the free-exciton energy spectrum in the intermediate-field regime is used to explain the experimental measurements.

• Received 18 August 1975

DOI:https://doi.org/10.1103/PhysRevB.13.761