Shallow-donor lasers in uniaxially stressed silicon

The effects of the terahertz-stimulated emission of Group-V donors (phosphorus, antimony, arsenic, bismuth) in uniaxially stressed silicon, excited by CO$_2$ laser radiation are experimentally studied. It is shown that uniaxial compressive stress of the crystal along the [100] direction increases the gain and efficiency of stimulated radiation, significantly decreasing the threshold pump intensity. The donor frequencies are measured and active transitions are identified in stressed silicon. The dependence of the residual population of active donor states on the uniaxial compressive stress along the [100] direction is theoretically estimated.