Si(001):B gas-source molecular-beam epitaxy: Boron surface segregation and its effect on film growth kinetics

H. Kim, G. Glass, T. Spila, N. Taylor, S. Y. Park, J. R. Abelson, J. E. Greene

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Abstract

B-doped Si(001) films, with concentrations CB up to 1.7 × 1022 cm-3, were grown by gas-source molecular-beam epitaxy from Si2H6 and B2H6 at Ts = 500-800°C. D2 temperature-programed desorption (TPD) spectra were then used to determine B coverages θB as a function of CB and Ts. In these measurements, as-deposited films were flash heated to desorb surface hydrogen, cooled, and exposed to atomic deuterium until saturation coverage. Strong B surface segregation was observed with surface-to-bulk B concentration ratios ranging up to 1200. TPD spectra exhibited β2 and β1 peaks associated with dideuteride and monodeuteride desorption as well as lower-temperature B-induced peaks β*2 and β*1. Increasing θB increased the area under β*2 and β*1 at the expense of β2 and β1 and decreased the total D coverage θD. The TPD results were used to determine the B segregation enthalpy, -0.53 eV, and to explain and model the effects of high B coverages on Si(001) growth kinetics. Film deposition rates R increase by ≥50% with increasing CB≳1 × 1019 cm-3 at Ts≤550°C, due primarily to increased H desorption rates from B-backbonded Si adatoms, and decrease by corresponding amounts at Ts≥600°C due to decreased adsorption site densities. At Ts≥700°C, high B coverages also induce {113} facetting.

Original languageEnglish
Pages (from-to)2288-2297
Number of pages10
JournalJournal of Applied Physics
Volume82
Issue number5
DOIs
Publication statusPublished - 1997 Sep 1

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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