PHOTOLUMINESCENCE OF HIGH-QUALITY SIGE QUANTUM-WELLS GROWN BY MOLECULAR-BEAM EPITAXY

A variety of SiGe quantum well (QW) samples were grown by solid-source molecular beam epitaxy (MBE) to study the influence of growth tempera ture T(G), and QW width L(z) on the photoluminescence (PL) properties. For all growth temperatures investigated (350-degrees-C less-than-or- equal-to T(G) less-than-or-equal-to 750-degrees-C) we found intense, w ell-resolved PL signals from the SiGe QWs. The PL intensity increases with T(G), and the stability against measurement temperature becomes b etter. A formerly reported PL band below the SiGe band edge is either completely absent, or very weak in the 4.2 K spectra of our samples. T hus, the defects or complexes responsible for this signal are obviousl y not inherent properties of MBE growth.