Band-gap and strain engineering in GeSn alloys using post-growth pulsed laser melting. (8th February 2023)

• Record Type: Journal Article
• Authors: Steuer, O; Schwarz, D; Oehme, M; Schulze, J; Mączko, H; Kudrawiec, R; Fischer, I A; Heller, R; Hübner, R; Khan, M M; Georgiev, Y M; Zhou, S; Helm, M; Prucnal, S
• Is Part Of: Journal of physics. Volume 35:Number 5(2023)
• Publication Date: 2023-02-08
• Subjects: GeSn -- group IV -- PLM -- pulse laser melting -- strain -- MBE -- band gap; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/aca3ea
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: The pseudomorphic growth of Ge1− x Sn x on Ge causes in-plane compressive strain, which degrades the superior properties of the Ge1− x Sn x alloys. Therefore, efficient strain engineering is required. In this article, we present strain and band-gap engineering in Ge1− x Sn x alloys grown on Ge a virtual substrate using post-growth nanosecond pulsed laser melting (PLM). Micro-Raman and x-ray diffraction (XRD) show that the initial in-plane compressive strain is removed. Moreover, for PLM energy densities higher than 0.5 J cm −2, the Ge0.89 Sn0.11 layer becomes tensile strained. Simultaneously, as revealed by Rutherford Backscattering spectrometry, cross-sectional transmission electron microscopy investigations and XRD the crystalline quality and Sn-distribution in PLM-treated Ge0.89 Sn0.11 layers are only slightly affected. Additionally, the change of the band structure after PLM is confirmed by low-temperature photoreflectance measurements. The presented results prove that post-growth ns-range PLM is an effective way for band-gap and strain engineering in highly-mismatched alloys.