Phosphorus incorporation during Si(001):P gas-source molecular beam epitaxy: Effects on growth kinetics and surface morphology

Journal Article · Sun Jun 15 00:00:00 EDT 2008 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2925798· OSTI ID:21137358

Cho, B; Bareno, J; Foo, Y L; Hong, S; Spila, T; Petrov, I; Greene, J E ^[1]

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1. Materials Science Department and the Frederick-Seitz Materials Research Laboratory, University of Illinois, 104 South Goodwin Ave., Urbana, Illinois 61801 (United States)

The effects of P doping on growth kinetics and surface morphological evolution during Si(001):P gas-source molecular beam epitaxy from Si{sub 2}H{sub 6} and PH{sub 3} at temperatures T{sub s}=500-900 deg. C have been investigated. With increasing PH{sub 3}/Si{sub 2}H{sub 6} flux ratio J{sub P/Si} at constant T{sub s}, we observe a decrease in the film growth rate R and an increase in the incorporated P concentration C{sub P}, both of which tend toward saturation at high flux ratios, which is accompanied by increased surface roughening and pit formation. At constant J{sub P/Si}, R increases with increasing T{sub s}, while C{sub P} initially increases, reaches a maximum at T{sub s}=700 deg. C, and then decreases at higher growth temperatures. We use in situ isotopically tagged D{sub 2} temperature programed desorption (TPD) to follow changes in film surface composition and dangling bond density {theta}{sub db} as a function of J{sub P/Si} and T{sub s}. Measurements are carried out on both as-deposited Si(001):P layers and P-adsorbed Si(001) surfaces revealing {beta}{sub 1} and {beta}{sub 2} peaks due to D{sub 2} desorption from Si monohydride and dihydride species, respectively, as well as the formation of a third peak {beta}{sub 3} corresponding to D{sub 2} desorption from mixed Si-P dimers. Dissociative PH{sub 3} adsorption on Si(001) results in a decrease in {theta}{sub db} and an initial increase in P surface coverage {theta}{sub P} with increasing T{sub s}. Saturation {theta}{sub P} values reach a maximum of {approx}1 ML at T{sub s}=550 deg. C, and decrease with T{sub s}>600 deg. C due to the onset of P{sub 2} desorption. Comparison of {theta}{sub P}(T{sub s}) results obtained during film growth with postdeposition C{sub P}(T{sub s}) results reveals the presence of strong P surface segregation. From measurements of {theta}{sub P} versus C{sub P} in Si(001):P layers grown as a function of T{sub s}, we obtain a P segregation enthalpy {delta}H{sub s}=-0.86 eV. By using the combined set of results, we develop a predictive model for C{sub P} versus T{sub s} and, J{sub P/Si} incorporating the dependence of the PH{sub 3} reactive sticking probability S{sub PH{sub 3}} on {theta}{sub P}, which provides an excellent fit to the experimental data.

• OSTI ID: 21137358
• Journal Information: Journal of Applied Physics, Vol. 103, Issue 12; Other Information: DOI: 10.1063/1.2925798; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ADSORPTION
CRYSTAL GROWTH
DESORPTION
ENTHALPY
MOLECULAR BEAM EPITAXY
MORPHOLOGY
PHOSPHORUS
PHOSPHORUS HYDRIDES
ROUGHNESS
SATURATION
SEGREGATION
SEMICONDUCTOR MATERIALS
SILANES
SILICON
SPECTROSCOPY
SURFACES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE RANGE 1000-4000 K
THIN FILMS