Adsorption and thermal reactions of disilane and the growth of Si films on Ge(100)-(2[times]1)

Journal Article · Mon Mar 15 00:00:00 EST 1993 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.47.6543· OSTI ID:6796636

Lin, D; Miller, T; Chiang, T ^[1]

---

1. Department of Physics, University of Illinois, 1110 West Green Street, Urbana, Illinois 61801 (United States) Materials Research Laboratory, University of Illinois, 104 South Goodwin Avenue, Urbana, Illinois 61801 (United States)

Scanning tunneling microscopy (STM), core-level photoemission spectroscopy using synchrotron radiation, and electron diffraction were employed to study the vapor-phase epitaxial growth of Si on Ge(100)-(2[times]1) using disilane (Si[sub 2]H[sub 6]). The dissociative chemisorption of a Si[sub 2]H[sub 6] molecule on Ge(100)-(2[times]1) at room temperature results in two Si-trihydride (SiH[sub 3]) radicals bonded onto two adjacent Ge dangling bonds. Some SiH[sub 2] and GeH species are also formed as a result of decomposition of SiH[sub 3]. An initial sticking coefficient of [similar to]0.5 is deduced from STM images. An exposure of more than 2 langmuirs (1 langmuir=10[sup [minus]6] Torr s) of disilane at room temperature saturates the surface with SiH[sub 3], SiH[sub 2], and GeH species, and the resulting surface is disordered. The total amount of Si on the saturated surface is about 1/2 monolayer (ML). Successive annealing of the saturated surface to higher temperatures causes the conversion of SiH[sub 3] to SiH[sub 2], the conversion of SiH[sub 2] to SiH, and the desorption of H from GeH. These processes become complete at about 600 K, and the resulting surface is a clean Ge(100)-(2[times]1) interspersed with about 1/2 ML of Si-monohydride (SiH)-(2[times]1) islands. Desorption of hydrogen from these SiH islands occurs at even higher annealing temperatures, and is accompanied by indiffusion of Si into the Ge substrate. This process becomes complete at about 690 K, and the final system configuration is a clean Ge(100)-(2[times]1) with about 1/2 ML of Si buried in the subsurface region. Multilayer Si deposition was performed by atomic layer epitaxy, i.e., cyclic disilane adsorption at [similar to]340 K followed by thermal conversion at 820 K. For up to 18 cycles, the resulting surface consists of Ge only. The change in surface morphology is studied by STM.

• DOE Contract Number: FG02-91ER45439
• OSTI ID: 6796636
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 47:11; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
SILANES
ADSORPTION
SILICON
CRYSTAL GROWTH
CHEMICAL BONDS
ELECTRON DIFFRACTION
EPITAXY
GERMANIUM
PHOTOEMISSION
TEMPERATURE EFFECTS
COHERENT SCATTERING
DIFFRACTION
ELEMENTS
EMISSION
HYDRIDES
HYDROGEN COMPOUNDS
METALS
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
SCATTERING
SECONDARY EMISSION
SEMIMETALS
SILICON COMPOUNDS
SORPTION
360602* - Other Materials- Structure & Phase Studies