Infrared Spectroscopy of GaAs Doped with Mn

We found that the fine structure related to Lyman spectra of [Mn$\text{}^{2+}$(d$\text{}^{5}$) + a hole] centers in GaAs was present only for samples with low Mn concentration. Such samples, at low temperature, did not show any hopping conductance within Mn impurity band. Magnetooptical measurements revealed that magnetic field induced splitting of the Lyman optical transitions was larger than Zeeman splitting observed for typical shallow acceptors in GaAs, like Be, Zn, and C. This experimental result proved that in the case of Mn acceptor impurity, the exchange coupling of a hole and the S = 5/2 Mn$\text{}^{2+}$(d$\text{}^{5}$) core could not be neglected, which was in accordance with the [Mn$\text{}^{2+}$(d$\text{}^{5}$) + a hole] model of the neutral Mn center in GaAs.