Resonance states of gallium impurity in uniaxially compressed germanium

To identify optical transitions that can excite long-wavelength stimulated radiation in uniaxially compressed Ga-doped germanium, the absorption and photoconduction spectra of this material were studied over a wide range of pressures in the [111] and [001] directions. It was found that some of the excited states of gallium impurity became resonant upon the buildup of pressure. The energy levels of these states reach the light-hole band, whereupon they enter this band and remain near its edge, showing up in the form of broad bands. No singularities confirming the existence of the impurity resonance states were observed in the spectra near the edge of the heavy-hole band.