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Abstract

The demonstration of direct bandgap emission from Hex-SiGe alloys marked a milestone in the development of Group IV light sources. The realization of quantum heterostructures would constitute the next step, allowing the creation of advanced low-dimensional optoelectronic devices based on the SiGe system. For example, lasing thresholds can be reduced by using the modified density of states of quantum wells (QWs). Here, we show for the first time the realization of quantum wells with a direct bandgap in the hex-SiGe system. Photoluminescence experiments on hex-Ge/Si0. 2Ge0. 8 indicate a type-I band alignment, with light emission up to room temperature. The QW thickness is varied, allowing us to shift the emission energy through quantum confinement. Additionally, the growth kinetics of hex-Ge/Si0. 2Ge0. 8 are studied, highlighting an unexpected growth rate increase for QWs in multi-quantum well (MQW) structures. The insights from the growth kinetics studies, in combination with the type-I alignment, pave the way towards novel MQW structures that were not possible with the SiGe system until now.