The no-phonon luminescence at 0.84 eV in GaAs:Cr-splitting under uniaxial stress

In a previous paper, (J. Physique Lett., vol.41, p.415, 1980), the authors proposed an interpretation of the fine structure of the no-phonon luminescence at 0.84 eV as arising from transitions at a substitutional Cr 2+ ion on a Ga site subjected to a perturbation of C 3v symmetry and advanced the main features of a theoretical model. In a second paper (ibid., vol.14, p.1855, 1981) they showed that this model leads to the proper description of the splittings in a magnetic field. Here they use this model to predict the splittings of the no-phonon luminescence lines under uniaxial stress, presenting experimental results and verifying that the model provides a correct interpretation of the observations. It is believed that this set of three papers offers a consistent view of the different experimental results on the defect. Few experimental facts-essentially the oscillator strengths for the electric-dipole transitions and the absence of shift of the low-energy lines for stress parallel to (110)-remains incompletely explained which is very satisfying with regard to the simplifying assumptions inherent in this type of calculation.