Investigations of Mn-doped ZnSe by photocapacitance and photocurrent techniques

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Abstract
The properties of a deep‐level center (the M center) occurring in ZnSe : Mn have been investigated by photocapacitance and photocurrent methods, using both transient and steady‐state techniques, over the temperture range 98–293 K. Spectra of the cross sections for optical transitions to the center from the valence band, σop, and from the center to the conduction band, σon, are presented. The threshold energy ΔEop for σop is 0.68 eV, independent of temperature, while the threshold energy ΔEon for σon varies with temperature at the same rate as the band gap Eg. The sum of the two threshold energies differs from Eg by less than 60 meV over the whole temperature range investigated. Thermal excitation from the valence band to the center is characterized by an energy ΔEtp of 0.71 eV. Because the sum ΔEop +ΔEon is close to Eg, and because the thermal energy ΔEtp is close to the optical energy ΔEop, then the Franck‐Condon shift of the M center is very small. This is consistent with the observed lack of thermal broadening of the photoionization spectra. The M center may be manganese or it may be a ’’self‐activated’’ center. These possibilities are discussed.

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