Epitaxial germanium deposited by MOVPE on InGaAs quantum dot stressors grown by MBE

Tensile strained Ge is considered as an enabling material for the integration of light emitting sources on Si because it shows unique indirect to direct bandgap transition and very high carrier mobilities (> 10.000 cm2/Vs). In the framework of this goal we aim to realize tensile germanium on In(Ga)As quantum dots (QD) stressors grown on GaAs and in this paper we focus on the study of deposition at different temperatures of Ge layers by Metal Organic Vapor Phase Epitaxy (MOVPE) on QD grown by Molecular Beam Epitaxy (MBE). The structures were characterized by Photoluminescence (PL) and Atomic Force Microscopy (AFM) before and after Ge epitaxy. Cross sectional TEM analysis shows that the Ge overlayer is epitaxially grown on the InGaAs/GaAs QD underlayer, with the same orientation. No structural defects are observed in the whole structures. Intermixing and In desorption occur at higher deposition temperature.