Intense photoluminescence observed in modulation doped Si/SiGe quantum well structures

p-type modulation doped wide Si/SiGe quantum well (QW) structures have been grown using a solid-source molecular beam epitaxy system. Very intense SiGe-related photoluminescence (PL) peaks, more than an order of magnitude stronger than for undoped SiGe QW structures, were observed from these samples. The increased PL intensity is believed to be due to the electron confinement in the vicinity of the QW, which enhances its excitonic recombination process in the SiGe layer, and it also indicates high crystalline quality of the grown materials with low incorporation of non-radiative defects. The luminescence properties of these modulation doped SiGe well structures have been studied under various excitation and measurement temperature conditions. Differences in PL spectra from MBE and some CVD grown Si/SiGe samples are discussed.