Characterization of Below-Gap Absorption in Semi-Insulating GaAs:Cr by Magneto-Circular Dichroism Spectrum

1 June 1988

journal article
Published by IOP Publishing in Japanese Journal of Applied Physics

Vol. 27 (6R)
https://doi.org/10.1143/jjap.27.979

Abstract

Magneto-circular dichroism (MCD) spectra in semi-insulating (SI) single crystals of GaAs:Cr have been measured between 0.7 and 1.4 eV with a magnetic field of about 10⁶ A/m (13 kOe) at temperatures above 20 K. Relatively strong MCD signals were observed in the below-gap energy region where a strong photoionization absorption band appears. Assuming that this strong absorption is caused by the charge transfer transition from the top of the valence band to the Cr-related deep state, we have analyzed the observed data by a theoretical calculation using a model adopted by Martinez et al., from which the Cr-related state was located 0.89 eV above the top of the valence band. The spin-orbit parameter used for the fitting is much smaller than that expected from the splitting in the top of the valence band. Modification of the theory used in this analysis is required.

Keywords

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