Hybrid Si molecular beam epitaxial regrowth for a strained Si _1-xGe_x/Si single-quantum-well electroluminescent device

An n-type Si contact layer for an electroluminescent (EL) diode was successfully grown on a Si/Si_1-xGe_x/Si single-quantum-well (SQW) structure by "hybrid" Si molecular beam epitaxy (MBE) for the first time. The hybrid MBE was performed by regrowing the Si contact layer in a solid-source MBE chamber after transferring the SQW sample through air from a gas-source (GS) MBE chamber, in which the starting SQW structure was grown. A (2×1) reconstruction was observed on a GSMBE-prepared Si(100) surface even after the SQW sample was exposed to air for up to 15 h. An excellent quality of the EL device was evidenced by the sharpest emission lines ever reported in the EL spectra of SiGe system. The spectral features of the EL and photoluminescence were found to be almost identical, and a well-resolved acoustic phonon replica was observed.