18th Microscopy of Semiconducting Materials Conference | |
STEM strain analysis at sub-nanometre scale using millisecond frames from a direct electron read-out CCD camera | |
物理学;材料科学 | |
Müller, K.^1 ; Ryll, H.^2 ; Ordavo, I.^2 ; Schowalter, M.^1 ; Zweck, J.^3 ; Soltau, H.^2 ; Ihle, S.^4 ; Strüder, L.^4 ; Volz, K.^5 ; Potapov, P.^5 ; Rosenauer, A.^1 | |
Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany^1 | |
PNSensor GmbH, Römerstraße 28, 80803 München, Germany^2 | |
Universität Regensburg, Universitätsstraße 31, 93040 Regensburg, Germany^3 | |
Max-Planck-Institut Halbleiterlabor, Otto-Hahn-Ring 6, 81739 München, Germany^4 | |
Philipps Universität Marburg, Hans-Meerwein-Straße, 35032 Marburg, Germany^5 | |
关键词: Compressive strain; Convergence angle; Cross correlations; Equivalent strains; Growth directions; Nanobeam electron diffraction; Spatial resolution; Strain profiles; | |
Others : https://iopscience.iop.org/article/10.1088/1742-6596/471/1/012024/pdf DOI : 10.1088/1742-6596/471/1/012024 |
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学科分类:材料科学(综合) | |
来源: IOP | |
【 摘 要 】
We report on strain analysis by nano-beam electron diffraction with a spatial resolution of 0.5nm and a strain precision in the 4-7·10-4range. Series of up to 160000 CBED patterns have been acquired in STEM mode with a semi-convergence angle of the incident probe of 2.6mrad, which enhances the spatial resolution by a factor of 5 compared to nearly parallel illumination. Firstly, we summarise 3 different algorithms to detect CBED disc positions accurately: selective edge detection and circle fitting, radial gradient maximisation and cross-correlation with masks. They yield equivalent strain profiles in growth direction for a stack of 5 InxGa1-xNyAs1-y/GaAs layers with tensile and compressive strain. Secondly, we use a direct electron read-out pnCCD detector with ultrafast readout hardware and a quantum efficiency close to 1 both to show that the same strain profiles are obtained at 200 times higher readout rates of 1kHz and to enhance strain precision to 3.5·10-4by recording the weak 008 disc.
【 预 览 】
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STEM strain analysis at sub-nanometre scale using millisecond frames from a direct electron read-out CCD camera | 808KB | download |