Growth of silicon(1-x) germanium(x) from disilane and digermane by gas-source molecular beam epitaxy
Bramblett, Thomas Richard
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/22620
Description
Title
Growth of silicon(1-x) germanium(x) from disilane and digermane by gas-source molecular beam epitaxy
Author(s)
Bramblett, Thomas Richard
Issue Date
1994
Doctoral Committee Chair(s)
Greene, J.E.
Department of Study
Engineering, Materials Science
Discipline
Engineering, Materials Science
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Materials Science
Language
eng
Abstract
The growth rate R of Si(001), Ge(001), and $\rm Si\sb{1-x}Ge\sb{x}(001)$ films deposited on Si(001)2 $\times$ 1 substrates from $\rm Si\sb2H\sb6$ and $\rm Ge\sb2H\sb6$ by gas-source molecular-beam epitaxy (GS-MBE) were determined as a function of temperature T$\sb{\rm s}$(300-950$\sp\circ$C) and impingement flux J (0.3-$7.7\times10\sp{16}$ cm$\sp{-2}$ s$\sp{-1}$). R(T$\sb{\rm s}$,J) curves for Si and Ge films were well described using a model, with no fitting parameters, based upon dissociative chemisorption followed by a series of surface decomposition reactions with the rate-limiting step being first-order hydrogen desorption from the surface monohydride. The hydrogen desorption activation energy for Si and Ge surfaces were found to be 2.04 eV and 1.56 eV, respectively. The zero-coverage reactive sticking probability in the impingement-flux-limited growth regime was found to be 0.036 and 0.052 for $\rm Si\sb2H\sb6$ and $\rm Ge\sb2H\sb6,$ respectively. The growth rate of SiGe alloys R$\sb{\rm SiGe}$ as a function of the bulk Ge content x was found to be a complex. In the surface-reaction-limited regime, R$\sb{\rm SiGe}$ increased with Ge surface coverage $\theta\sb{\rm Ge}$ due to the lower activation energy of H$\sb2$ desorption from Ge than from Si. However, in the impingement-flux-limited regime R$\sb{\rm SiGe}$ decreases with $\theta\sb{\rm Ge}$ due to the lower reactive sticking probability of $\rm Si\sb2H\sb6$ on Ge surface sites with respect to on Si sites. The Ge fraction, x1$\sb{\rm Ge}$, of SiGe alloys was determined as a function of growth temperature T$\sb{\rm s}$ and incident flux ratios $\rm J\sb{Ge2H6}/J\sb{Si2H6}.$ The results were explained by a kinetic model accounting for four simultaneous reaction pathways: reaction of $\rm Si\sb2H\sb6$ with Si surface sites, $\rm Si\sb2H\sb6$ with Ge sites, $\rm Ge\sb2H\sb6$ with Si sites, and $\rm Ge\sb2H\sb6$ with Ge sites. The cross-term reactive sticking probabilities, $\rm S\sbsp{Ge2H6}{Si}$ and $\rm S\sbsp{Si2H6}{Ge}$, were estimated to be 0.33 and $5.2\times10\sp{-3}$ respectively.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
