Kinetics of Si{sub 1{minus}x}Ge{sub x}(001) growth on Si(001)2{times}1 by gas-source molecular-beam epitaxy from Si{sub 2}H{sub 6} and Ge{sub 2}H{sub 6}

Journal Article · Tue Dec 01 04:00:00 EST 1998 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.368882· OSTI ID:664665

Kim, H; Taylor, N; Bramblett, T R; Greene, J E ^[1]

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1. Department of Materials Science, the Coordinated Science Laboratory and the Materials Research Laboratory, University of Illinois, 1101 West Springfield, Urbana, Illinois 61801 (United States)

Si{sub 1{minus}x}Ge{sub x} layers with {ital x} ranging from 0 to 0.30 were grown on Si(001)2{times}1 substrates at temperatures ranging from 450 to 950thinsp{degree}C by gas-source molecular-beam epitaxy (GS-MBE) from Si{sub 2}H{sub 6} and Ge{sub 2}H{sub 6}. In the low-temperature surface-reaction-limited growth regime, the deposition rate R{sub SiGe} increases with increasing Ge concentration due to an enhancement in the hydrogen desorption rate resulting in a correspondingly higher steady-state dangling bond density. In the high-temperature impingement-flux-limited regime, where the steady-state hydrogen coverage approaches zero, R{sub SiGe} is controlled by the Si{sub 2}H{sub 6} and Ge{sub 2}H{sub 6} reactive sticking probabilities {ital S} which decrease with increasing Ge{sub 2}H{sub 6} flux but are not strongly temperature dependent. S{sub Si{sub 2}H{sub 6}} and S{sub Ge{sub 2}H{sub 6}} range from 0.036 and 0.28 on Si(001) to 0.012 and 0.094 during growth of Si{sub 0.82}Ge{sub 0.18} at T{sub s}=800thinsp{degree}C. In both growth regimes, large changes in R{sub SiGe} require only modest increases in incident Ge{sub 2}H{sub 6} to Si{sub 2}H{sub 6} flux ratios, J{sub Ge{sub 2}H{sub 6}}/J{sub Si{sub 2}H{sub 6}}, due to Ge segregation which is strongly coupled to the steady state hydrogen coverage. The Ge to Si ratio in as-deposited films increases linearly, while S{sub Ge{sub 2}H{sub 6}}/S{sub Si{sub 2}H{sub 6}} remains constant, with increasing J{sub Ge{sub 2}H{sub 6}}/J{sub Si{sub 2}H{sub 6}}. Hydrogen desorption and Ge segregation rates, together with Si{sub 2}H{sub 6} and Ge{sub 2}H{sub 6} reactive sticking probabilities, were quantitatively determined from D{sub 2} temperature-programmed desorption (TPD) measurements. The combined results from film growth kinetics and TPD studies, together with the assumption of linear superposition, were then used to develop a predictive model, with no fitting parameters, for R{sub SiGe}(T{sub s},J{sub Si{sub 2}H{sub 6}},J{sub Ge{sub 2}H{sub 6}}) during Si{sub 1{minus}x}Ge{sub x} GS-MBE. {copyright} {ital 1998 American Institute of Physics.}

• OSTI ID: 664665
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 11 Vol. 84; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHEMISORPTION
DESORPTION
GERMANIUM SILICIDES
HETEROJUNCTIONS
HYDROGEN
MOLECULAR BEAM EPITAXY
REACTION KINETICS
SEGREGATION
SEMICONDUCTOR MATERIALS
SILANES
SILICON
TEMPERATURE DEPENDENCE
THIN FILMS