Optical Detection of Electron Spin Resonance in Compound Semiconductors.

The electronic structures of defects and impurities in GaSe-S alloys, GaAsCr, GaAs Zn, ColTe and SiSi02 have been investigated using the techniques of optically detected magnetic resonance ODMR and spin sensitive photoconductivity SSP. In GaSe-S the ODMR has been used to study a wide range of triplet states. The photoluminescence bands associated with triplet state deexcitation change linearly with composition. The g-values of the triplet state ODMR as well as the crystal field splitting parameter also change linearly with alloy composition. Similiar work on GaAs Cr shows that the ODMR and SSP spectra are not associated with internal transitions of the ST2 state of the Cr2 ion in GaAs. At least two spin triplet state resonances are observed due to electron-hole recombination at CR2 ions in distorted Ga3 sites. The ODMR results for GaAsZn are interpreted as recombination luminescence at substitutional Zn2 impurity ions with distortion axis along a III axis. In CdTe resonances observed with g-values of 1.61 and 1.35 have been identified as due to electrons recombining at neutral acceptors or donors and holes recombining at neutron donors respectively.