2026-09-22T15:14:21Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/20087 2023-07-10 col_2142_5131 col_2142_13836 com_2142_5130 com_2142_13835 com_2142_234

Greene, Joseph E. Tsu, Robert Yung-Hsi 2011-05-07T12:28:23Z 2011-05-07T12:28:23Z 10000-01-01 1993 Single-crystal Si films have been grown on Si(001)2x1 substrates by UV-photostimulated atomic-layer epitaxy (ALE) from Si$\sb2$H$\sb6.$ The ALE deposition rate R per growth cycle remains constant at 0.43 monolayers (ML), 1 ML = $6.8\times10\sp{14}$ cm$\sp{-2}$, over a wide range of deposition parameters: growth temperature (T$\sb{\rm S}$ = 180-400$\sp\circ$C), Si$\sb2$H$\sb6$ exposure, UV laser energy density, and number of UV laser pulses per cycle. A film growth model, based upon the results of adsorption/desorption measurements, film growth experiments, and Monte Carlo simulations, is used to describe the reaction pathway for the process. Si$\sb2$H$\sb6$ is dissociatively adsorbed on Si surface dimers as two SiH$\sb3$ radicals which, as shown by electron energy loss spectroscopy (EELS) and reflection high-energy electron diffraction (RHEED), subsequently dissociate to SiH$\sb2$ and H. The saturated H-terminated surface is stable and passive to further Si$\sb2$H$\sb6$ exposure. ArF or KrF laser pulses $(\simeq$20 ns) are used to desorb H, following a Si$\sb2$H$\sb6$ exposure, and the growth is repeated until the desired film thickness is obtained. Transmission electron microscopy (TEM) and cross-sectional TEM together with selective area and convergent-beam electron diffraction patterns show that the ALE films are epitaxial layers with no observed extended defects or strain. The Si$\sb2$H$\sb6$ sticking probability at 25$\sp\circ$C is found to be $\simeq$0.5 while the saturation coverage is $\simeq$0.5 ML on Ge(001)2x1. Scanning tunneling microscopy (STM) observations show the adsorbed overlayers exhibit regions of local ordering, in contrast to the case for Si$\sb2$H$\sb6$ on Si(001), and are composed of SiH$\sb2$ and GeH with evidence of residual SiH$\sb3.$ Hydrogen desorption is observed at temperatures as low as 150$\sp\circ$C, admolecules are mobile at 270$\sp\circ$C, and complete ordering is observed by 330$\sp\circ$C. Film growth on Ge(001) is observed to proceed via a mixed mode. Made available in DSpace on 2011-05-07T12:28:23Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9411805.pdf: 5586168 bytes, checksum: 8c56654dc11706df09b61523289220d0 (MD5) Previous issue date: 1993 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:41:28Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:17:57-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI9411805 (UMI)AAI9411805 http://hdl.handle.net/2142/20087 eng Copyright 1993 Tsu, Robert Yung-Hsi Physics, Condensed Matter Engineering, Metallurgy Engineering, Materials Science Mechanisms and kinetics of silicon atomic-layer epitaxy on silicon(001)2x1 and germanium(001)2x1 text Materials Science and Engineering Materials Science and Engineering University of Illinois at Urbana-Champaign Dissertation Ph.D.