Regensburg 2022 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 22: Heterostructures, Interfaces and Surfaces
HL 22.1: Talk
Wednesday, September 7, 2022, 15:00–15:15, H33
Band-gap and strain engineering in GeSn alloys using post-growth pulsed laser melting — •O. Steuer1, D. Schwarz2, M. Oehme2, J. Schulze3, H. Maczko4, R. Kudrawiec4, I. Fischer5, R. Heller1, R. Hübner1, M. Khan1, Y. Georgiev1, S. Zhou1, M. Helm1, and S. Prucnal1 — 1Helmholtz-Zentrum HZDR, GER — 2University of Stuttgart, GER — 3Fraunhofer IIS, GER — 4Wroclaw University, POL — 5TU Cottbus-Senftenberg, GER
Alloying Ge with Sn enables effective band-gap engineering and improves significantly the charge carrier mobility. The pseudomorphic growth of Ge1-xSnx on Ge causes in-plane compressive strain, which degrades the superior properties of the Ge1-xSnx alloys. Therefore, efficient strain engineering is required. In this talk, we will present strain and band-gap engineering in GeSn alloys grown on a Ge virtual substrate using post-growth nanosecond pulsed laser melting (PLM). Micro-Raman spectroscopy and X-ray diffraction show that the initial in-plane compressive strain is removed. Moreover, for PLM energy densities higher than 0.5 J cm-2, the Ge0.89Sn0.11 layer becomes tensile strained. Simultaneously, as revealed by Rutherford Backscattering spectrometry, cross-sectional transmission electron microscopy investigations and X-ray diffraction, the crystalline quality and Sn-distribution in PLM-treated Ge0.89Sn0.11 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.