Annealing and oxidation of silicon oxide films prepared by plasma-enhanced chemical vapor deposition

Journal Article · Sat Jan 01 00:00:00 EST 2005 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.1829789· OSTI ID:20664983

Chen, X Y; Lu, Y F; Tang, L J; Wu, Y H; Cho, B J; Xu, X J; Dong, J R; Song, W D ^[1]

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1. Department of Electrical and Computer Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260 (Singapore)

We have investigated phase separation, silicon nanocrystal (Si NC) formation and optical properties of Si oxide (SiO{sub x}, 0<x<2) films by high-vacuum annealing and dry oxidation. The SiO{sub x} films were deposited by plasma-enhanced chemical vapor deposition at different nitrous-oxide/silane flow ratios. The physical and optical properties of the SiO{sub x} films were studied as a result of high-vacuum annealing and thermal oxidation. X-ray photoelectron spectroscopy (XPS) reveals that the as-deposited films have a random-bonding or continuous-random-network structure with different oxidation states. After annealing at temperatures above 1000 deg. C, the intermediate Si continuum in XPS spectra (referring to the suboxide) split to Si peaks corresponding to SiO{sub 2} and elemental Si. This change indicates the phase separation of the SiO{sub x} into more stable SiO{sub 2} and Si clusters. Raman, high-resolution transmission electron microscopy and optical absorption confirmed the phase separation and the formation of Si NCs in the films. The size of Si NCs increases with increasing Si concentration in the films and increasing annealing temperature. Two photoluminescence (PL) bands were observed in the films after annealing. The ultraviolet (UV)-range PL with a peak fixed at 370-380 nm is independent of Si concentration and annealing temperature, which is a characteristic of defect states. Strong PL in red range shows redshifts from {approx}600 to 900 nm with increasing Si concentration and annealing temperature, which supports the quantum confinement model. After oxidation of the high-temperature annealed films, the UV PL was almost quenched while the red PL shows continuous blueshifts with increasing oxidation time. The different oxidation behaviors further relate the UV PL to the defect states and the red PL to the recombination of quantum-confined excitions.

• OSTI ID: 20664983
• Journal Information: Journal of Applied Physics, Vol. 97, Issue 1; Other Information: DOI: 10.1063/1.1829789; (c) 2005 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
ABSORPTION
ANNEALING
CHEMICAL VAPOR DEPOSITION
CONFINEMENT
CRYSTAL DEFECTS
NANOSTRUCTURES
NITROUS OXIDE
OPTICAL PROPERTIES
OXIDATION
PHOTOLUMINESCENCE
PLASMA
RANDOMNESS
RECOMBINATION
SILICON OXIDES
SPECTRAL SHIFT
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY
ULTRAVIOLET RADIATION
VALENCE
X-RAY PHOTOELECTRON SPECTROSCOPY