B-incorporation kinetics and charge transport property of silicon germanide(001) layer grown by GS-MBE from silicon hydride, germanium hydride, and boron hydride

Lu, Qing

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Description

Title

B-incorporation kinetics and charge transport property of silicon germanide(001) layer grown by GS-MBE from silicon hydride, germanium hydride, and boron hydride

Author(s)

Lu, Qing

Issue Date

1996

Doctoral Committee Chair(s)

Greene, Joseph E.

Department of Study

Materials Science and Engineering

Discipline

Materials Science and Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Engineering, Electronics and Electrical
• Physics, Condensed Matter
• Engineering, Materials Science

Language

eng

Abstract

• The growth rates of Si(001) and Ge(001) by gas-source molecular-beam epitaxy (GS-MBE) from $\rm Si\sb2H\sb6$ and $\rm Ge\sb2H\sb6$ as a function of T$\sb{\rm s}$ are well described by a model based upon dissociative $\rm Si\sb2H\sb6$ and $\rm Ge\sb2H\sb6$ chemisorption followed by a series of surface decomposition reactions with the rate-limiting step being first-order hydrogen desorption from Si and Ge monohydride for which the activation energy is 2.04 and 1.56 eV, respectively. The zero-coverage reactive sticking probability of $\rm Si\sb2H\sb6$ on Si(001)2 x 1 ($\rm Ge\sb2H\sb6$ on Ge(001)2 x 1) in the impingement-flux-limited growth regime was found to be $\rm S\sbsp{Si\sb2H\sb6}{Si} = 0.036\ (S\sbsp{Ge\sb2H\sb6}{Ge} = 0.052).$ The growth rate of $\rm Si\sb{1-x}Ge\sb{x}$ alloys R$\sb{\rm SiGe}$ decreases somewhat with increasing $\rm G\sb2H\sb6$ in the flux-limited growth mode while dramatically increasing $\rm R\sb{SiGe}$ in the surface-reaction-limited regime.
• B-doped Si(001), Ge(001), and $\rm Si\sb{1-x}Ge\sb{x}(001)2 x 1$ films were grown on Si(001) and Ge(001) substrates by GS-MBE using $\rm Si\sb2H\sb6,\ Ge\sb2H\sb6$, and $\rm B\sb2H\sb6.$ For constant $\rm Si\sb2H\sb6$ and/or $\rm Ge\sb2H\sb6$ fluxes, B concentrations $\rm C\sb{B}\ (5\times 10\sp{16}-5\times 10\sp{19}\ cm\sp{-3})$ were found to increase linearly with increasing flux $\rm B\sb2H\sb6$ at constant film growth temperatures T$\rm\sb{s}$ and to decrease exponentially with 1/T$\sb{\rm s}$ at constant $\rm B\sb2H\sb6$ fluxes. $\rm B\sb2H\sb6$ reactive sticking probabilities ranged from $\simeq 6.4\times 10\sp{-4}$ at T$\rm\sb{s} = 600\sp\circ C$ to $1.4\times 10\sp{-3}$ at 950$\sp\circ$C for B doped Si(001) and from $8\times10\sp{-4}$ at 300$\sp\circ$C to $2\times10\sp{-5}$ at 400$\sp\circ$ for B doped Ge(001).
• Structural analysis by in-situ reflection high energy electron diffraction combined with post-deposition high-resolution plan-view and cross-sectional transmission electron microscopy, high-resolution X-ray diffraction, and reciprocal lattice mapping showed that all films were high-quality single crystals.
• A comparison of quantitative secondary-ion mass spectrometry (SIMS) and temperature-dependent Hall-effect measurements showed that B was incorporated into substitutional electrically-active sites under all growth conditions investigated. SIMS B depth-profiles from modulation-doped samples were abrupt with no indication of surface segregation and $\delta$-doped layers were grown. The hole drift mobility in fully-strained alloys was found to increase while the Hall mobility decreased with increasing Ge fraction yielding a Hall scattering factor $\gamma$ which ranged from 0.77 for Si to 0.26 for alloys with x = 0.28. Room-temperature hole mobilities were equal to the best reported bulk $\rm Si\sb{1-x}Ge\sb{x}{:}B$ values and ranged, with p = $2\rm\times 10\sp{18}\ cm\sp{-3}$ for example, from 160 cm$\rm\sp2V\sp{-1} s\sp{-1}$ for x = 0.28 to 110 $\rm cm\sp2V\sp{-1}s\sp{-1}$ for x = 0.05 to 86 for pure Si.

Type of Resource

text

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Copyright and License Information

Copyright 1996 Lu, Qing

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