Spectroscopic ellipsometric properties of Ga1-xFexAs dilute magnetic semiconductors

Abstract

We report pseudodielectric function data < epsilon > = < epsilon(1) > + i < epsilon(2) > of Ga1-x FexAs semiconductors grown on GaAs substrates. The data were obtained front 1.5 to 6 eV using spectroscopic ellipsometry. Critical point (CP) parameters were obtained by fitting model lineshapes to numerically calculated second energy derivatives of < epsilon >. The bandgap energies of E-1, E-1 + Delta(I), E-0&apos;, and E-2 were determined. We observed an increase of the E-1 and E-1 + Delta(1) gap energy similar to that of ZnFexSe1-x. The linewidth of CPs increased with increasing Fe compositions. The band gap energy shifts were mainly attributed to the alloying effect because the strain effect on the band gap energies was negligible. We also discuss the band gap shift in terms of an sp-d hybridization model.