Excitonic spectra and energy band structure of ZnAl2Se4 crystals

Abstract

Absorption, reflection and wavelength modulated reflection spectra were investigated in ZnAl2Se4 crystals. The energy positions of ground and excited states for three excitonic series (А, В and С) were determined. The main parameters of excitons and more precise values of energy intervals V1(Γ7)–C1(Γ6), V2(Γ6)–C1(Γ6), and V3(Γ7)–C1(Γ6) were estimated. Values of splitting due to crystal field and spin–orbital interaction were calculated. Effective masses of electrons (mC1∗) and holes (mV1∗, mV2∗, mV3∗) were estimated. Reflection spectra contours in excitonic region were calculated using dispersion equations. Optical functions for E > Eg from measured reflection spectra were assigned on the base of Kramers–Kronig relations.