Room-temperature photoluminescence of Ge<i>m</i>Si<i>n</i>Ge<i>m</i> structures

Abstract

Photoluminescence of pseudomorphic Ge wells grown by conventional molecular beam epitaxy on Si substrate is studied. The samples consist of p-type doped Gem–Sin–Gem structures embedded in a Si1−xGex alloy. The luminescence lines shift to lower energy with increasing m, the observed band gap agrees with subband calculation based on an effective mass approximation. The temperature stability of the luminescence depends on m. In the case of m=4 the luminescence persists up to room temperature with only small reduction in intensity. The activation energies determined from the exponential drop of luminescence intensity agree with band discontinuities in the sample structures.