On the phonon-assisted relaxation of excited bismuth donor states in uniaxially stressed silicon

The low-temperature phonon-assisted relaxation rates of the excited states of bismuth donors in a silicon crystal uniaxially stressed in the [100] crystallographic direction are calculated. The states belonging to the lower (2$\Delta$) and upper (4$\Delta$) valleys of the silicon conduction band are considered. It is shown that the population inversion of bismuth donor states in the upper (4$\Delta$) valleys of the silicon conduction band under optical pumping is possible.