Magnetic resonance of x-point shallow donors in AlSb-Te bulk crystals and AlSb MBE layers.

We report e lectron-paramagnetic-resonance (EPR) results for bulk AlSb:Te crystals as well as optically detected magnetic resonance (ODMR) data for molecular- beam-epitaxy (MBE) grown AlSb layers on (001) semi- insulating GaAs substrate. The bulk materials reveal an isotropic EPR signal at g is equal to 1.878 plus or minus 0.005 which is identified as that of the shallow Te donor associated with the X-point conduction band minima. The increase of the donor EPR amplitude following illumination suggests a bistable DX-type behavior for the Te donor in AlSb. Photo-luminescence measurements on the AlSb MBE layers reveal a broad featureless emisson band peaked at 0.95 eV. An isotropic ODMR line is observed on this band. Within the error limits, its g-value, g is equal to 1.883 plus or minus 0.005 is identical with that found from the present EPR on bulk Te doped AlSb. This observation is consistent with secondary ion mass spectroscopy measurements of the nominally undoped epitaxial layers wh ich detected a large residual Te concentration due to a contaminated Sb charge.