Ge/SiGe quantum wells on Si(111): Growth, structural, and optical properties

The epitaxial growth of Ge/Si0.15Ge0.85 multiple quantum wells (MQWs) on Si(111) substrates is demonstrated. A 3 mu m thick reverse, double-step virtual substrate with a final composition of Si0.10Ge0.90 has been employed. High resolution XRD, TEM, AFM and defect etching analysis has been used for the study of the structural properties of the buffer and of the QWs. The QW stack is characterized by a threading dislocation density of about 3 x 10(7) cm(-2) and an interdiffusion layer at the well/barrier interface of 2.1 nm. The quantum confined energy levels of this system have been calculated using the k.p and effective mass approximation methods. The Ge/Si0.15Ge0.85 MQWs have been characterized through absorption and photoluminescence measurements. The optical spectra have been compared with those of Ge/Si0.15Ge0.85 QWs grown on Si(001) through a thick graded virtual substrate. (C) 2014 AIP Publishing LLC.