Mechanical damage induced luminescence band in GaAs

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Abstract
In this paper we report the observation of a new luminescence band at ∼1.4 eV in the low temperature (10 K) spectrum from bulk GaAs crystals when they are subjected to surface damage by saw cutting, mechanical polishing, and scribing. The band is observed in all crystals, independent of the growth method, dopant, and conductivity type. The peak position of the 1.4-eV band shifts to lower energy with decreasing excitation intensity by as much as 7 meV per decade change in excitation power. The luminescence quenches thermally above ∼30 K with an activation energy of 33±7 meV. We suggest that this new luminescence is a donor-acceptor pair transition involving defects introduced by the surface damage. The mechanical damage, as monitored by the intensity of the luminescence band, is found to extend into the crystal by 10–20 μm depending on the severity of the damage, and it anneals out at ≳400 °C.