Postgrowth of a Si contact layer on an air-exposed Si1−xGex/Si single quantum well grown by gas-source molecular beam epitaxy, for use in an electroluminescent device

Abstract

A Si contact layer for an electroluminescent (EL) diode was successfully grown on a Si1−xGex/Si single quantum well (SQW) layer by ‘‘hybrid’’ Si molecular beam epitaxy (MBE). The ‘‘hybrid’’ MBE was performed by growing the Si contact layer in a solid-source MBE chamber after transferring the sample through air from a gas-source MBE (GSMBE) chamber in which the starting SQW layer was initially grown by using disilane (Si2H6) and germane (GeH4). The growth characteristics of the hybrid MBE were investigated by in situ monitoring of the reflection high energy electron diffraction. A (2×1) reconstruction was observed even after the sample was exposed to air for up to 15 h on a GSMBE-prepared Si(100) surface. Evidence of the excellent quality of the EL device was provided by the sharpest emission lines, a full width at half maximum of ≊5.5 meV. The spectral features of the EL and photoluminescence were found to be almost identical, and a well-resolved acoustic phonon replica was observed. Linear polarization for a no-phonon replica of EL was also observed along SQW plane.