X-ray diffraction study of strain relaxation, spontaneous compositional gradient, and dislocation density in GeSn/Ge/Si(100) heterostructures
- 1 July 2020
- journal article
- research article
- Published by IOP Publishing in Semiconductor Science and Technology
- Vol. 35 (7), 075009
- https://doi.org/10.1088/1361-6641/ab883c
Abstract
The strain relaxation, depth profiles of composition and density of dislocations in GeSn epilayers were studied by using the x-ray diffraction. Regions with uniform and graded composition, different levels of strain relaxation, and dislocation density were found in the GeSn layers grown at fixed growth conditions. At the initial stage of growth, the GeSn layer is under similar to 8 x 10(-3)compressive strain, and the Sn composition is close to the target value of 6.6%. With increasing layer thickness, the Sn content is enhanced by 0.85 +/- 0.12% due to the relief of compressive strain down to similar to 5.0 x 10(-4). The plastic strain relaxation is dominated by 60 degrees misfit dislocations at the GeSn/Ge interface, where their density is 3 x 10(5)cm(-1). The relaxed GeSn layer serves as a buffer for the high-quality GeSn overlayer with uniform and enhanced Sn composition. The laboratory-based x-ray diffraction is shown as a non-destructive reliable technique for strain, composition, and defects characterization, as an alternative to secondary ion mass spectrometry and transmission electron microscope techniques.Funding Information
- Air Force Office of Scientific Research (FA9550-19-1-0341)
This publication has 34 references indexed in Scilit:
- Characterization of SiGe thin films using a laboratory X-ray instrumentJournal of Applied Crystallography, 2013
- Design of an electrically pumped SiGeSn/GeSn/SiGeSn double-heterostructure midinfrared laserJournal of Applied Physics, 2010
- High-performance Ge-on-Si photodetectorsNature Photonics, 2010
- Ternary GeSiSn alloys: New opportunities for strain and band gap engineering using group-IV semiconductorsThin Solid Films, 2010
- Potentialities and basic principles of controlling the plastic relaxation of GeSi/Si and Ge/Si films with stepwise variation in the compositionSemiconductors, 2008
- TIN-BASED GROUP IV SEMICONDUCTORS: New Platforms for Opto- and Microelectronics on SiliconAnnual Review of Materials Research, 2006
- Diffuse x-ray scattering from misfit and threading dislocations inthin layersPhysical Review B, 2006
- Advances in SiGeSn/Ge TechnologyMRS Proceedings, 2006
- Tensile strained epitaxial Ge films on Si(100) substrates with potential application in L-band telecommunicationsApplied Physics Letters, 2004
- X-ray diffraction peaks due to misfit dislocations in heteroepitaxial structuresPhysical Review B, 1997