TY - JOUR
T1 - Microstructural evolution of Ge/Si(1 0 0) nanoscale islands
AU - Smith, David
AU - Chandrasekhar, D.
AU - Chaparro, S. A.
AU - Crozier, Peter
AU - Drucker, Jeffery
AU - Floyd, M.
AU - McCartney, Martha
AU - Zhang, Y.
N1 - Funding Information:
This work was supported by NSF Grants DMR 9496296, DMR-9724305, DMR-9804310 and DMR-0196018. The electron microscopy was performed at the Center for High Resolution Electron Microscopy at Arizona State University.
PY - 2003/12
Y1 - 2003/12
N2 - This paper reports our detailed investigation of the microstructural evolution of Ge/Si(1 0 0) nanoscale islands grown by deposition of pure Ge onto Si(1 0 0) substrates using molecular beam epitaxy. Substrate temperatures during growth were varied in the range 400≤T≤700°C, although we have mostly concentrated our attention here on studying samples grown at T = 550°C, 650°C and 700°C. Atomic-force microscopy was first used ex situ to document the shape and size evolution of the Ge/Si(100) islands as a function of the growth conditions (Ge coverage, substrate temperature). A range of transmission electron microscopy techniques including energy-dispersive X-ray spectroscopy and electron energy-loss spectroscopy was then used to further investigate the local microstructure and composition of the islands. Substantial Si diffusion into the Ge islands was measured, and trenches extending well into the Si substrate were also observed at the bases of larger clusters grown with T≥550°C. Plan-view imaging of selected samples using both bright-field and dark-field imaging modes identified the critical size for dislocation formation. Cross-sectional high-resolution imaging enabled the strain-relieving dislocations to be identified, and also confirmed the multi-facetted and often asymmetrical shapes of larger islands.
AB - This paper reports our detailed investigation of the microstructural evolution of Ge/Si(1 0 0) nanoscale islands grown by deposition of pure Ge onto Si(1 0 0) substrates using molecular beam epitaxy. Substrate temperatures during growth were varied in the range 400≤T≤700°C, although we have mostly concentrated our attention here on studying samples grown at T = 550°C, 650°C and 700°C. Atomic-force microscopy was first used ex situ to document the shape and size evolution of the Ge/Si(100) islands as a function of the growth conditions (Ge coverage, substrate temperature). A range of transmission electron microscopy techniques including energy-dispersive X-ray spectroscopy and electron energy-loss spectroscopy was then used to further investigate the local microstructure and composition of the islands. Substantial Si diffusion into the Ge islands was measured, and trenches extending well into the Si substrate were also observed at the bases of larger clusters grown with T≥550°C. Plan-view imaging of selected samples using both bright-field and dark-field imaging modes identified the critical size for dislocation formation. Cross-sectional high-resolution imaging enabled the strain-relieving dislocations to be identified, and also confirmed the multi-facetted and often asymmetrical shapes of larger islands.
KW - A1. Characterization
KW - A1. Defects
KW - A1. Diffusion
KW - A1. Nanostructures
KW - A3. Molecular beam epitaxy
KW - B1. Germanium silicon alloys
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U2 - 10.1016/j.jcrysgro.2003.07.025
DO - 10.1016/j.jcrysgro.2003.07.025
M3 - Article
AN - SCOPUS:0142126700
SN - 0022-0248
VL - 259
SP - 232
EP - 244
JO - Journal of Crystal Growth
JF - Journal of Crystal Growth
IS - 3
ER -