Photoluminescence from Ge/Si Nanocrystals Embedded in Silicon Oxide Matrix Annealed in Hydrogen Gas
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1145-MM04-11
Photoluminescence from Ge/Si Nanocrystals Embedded in Silicon Oxide Matrix Annealed in Hydrogen Gas
S. Uekusa and N. Kosaka Department of Electronics and Bioinformatics, School of Science and Technology, Meiji university, 1-1-1, Higashi-mita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
ABSTRACT Photoluminescence (PL) spectra from Si nanocrystals embedded in silicon oxide matrix (SiSiO2) thin films, Ge embedded in silicon oxide matrix (Ge-SiO2) thin films and both Ge and Si embedded in silicon oxide matrix (Ge/Si-SiO2) thin films prepared by RF magnetron sputtering were investigated. All as-deposited thin films were annealed for 1h in the temperature range from 500oC to 1100oC in Ar or H2 atmosphere. The PL spectra of Si-SiO2 thin films exhibited red luminescence at an annealing temperature of 1100oC and the PL intensity of the sample annealed in H2 gas increased by a factor of approximately 6.3 in comparison with sample annealed in Ar gas. Subsequently, The PL intensity of main peak centered at about 400 nm (Vband) of Ge-SiO2 thin films annealed in H2 gas exhibited strong comparison with the sample annealed in Ar gas. Finally, the PL spectra of Ge/Si-SiO2 thin films exhibited strong peak centered at approximately 500-530 nm (G-band) besides V-band and others in the temperature range from 700oC to 1000oC. The PL intensity of G-band of the samples annealed in H2 gas exhibited weak comparison with Ar gas. INTRODUCTION Since the discovery of visible luminescence from porous silicon at room temperature in the 1990s [1], semiconductor nanoparticles have been studied by many researchers. Because silicon (Si), which is a group IV element, is a semiconductor with many advantages including abundant natural resources, no toxicity, and a high melting point, it is expected to be used as a substitute material for group III-V compound semiconductors used for current photonics. Furthermore, germanium (Ge), which is also a group IV element, has attracted researcher’s attention. Though Bulk Si and Ge are originally indirect-gap semiconductors, when the size of these materials is reduced to Bour radius (Si: about 4.3 nm, Ge: about 18 nm), visible luminescence is emitted due to the quantum confinement effects. The states on the surface of a nanoparticle mainly determine its physical properties. Termination of the oxide (SiO2) or the hydrogen on the surface is a typical method of terminating the surface of semiconductor nanoparticles such as nanocrystalline Si (nc-Si). Ion implantation [2], CVD [3], and RF magnetron sputtering methods [4-6] have been used by many researchers as methods of forming nanoparticles. It was reported that violet (3.13.2 eV) and blue (2.58-2.95 eV) luminescence can be obtained from Ge nanocrystals embedded in a silicon oxide matrix (Ge-SiO2) and that red (1.3-1.5 eV) luminescence can be obtained from Si nanocrystals embedded in SiO2 (Si-SiO2) [7,8]. In the future, Si and Ge are expected to be used as more environmentally friendly materials for next generation optical device such as green-light-e
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