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Please use this identifier to cite or link to this item: http://dspace.library.iitb.ac.in/jspui/handle/10054/4459

Title: Spectroscopic ellipsometry studies of GaN films deposited by reactive rf sputtering of GaAs target
Authors: BISWAS, A
BHATTACHARYYA, D
SAHOO, NK
YADAV, BS
MAJOR, SS
SRINIVASA, RS
Keywords: light-emitting-diodes
optical-properties
polycrystalline gan
thin-films
hexagonal gan
amorphous-semiconductors
si substrate
in-situ
growth
ultraviolet
Issue Date: 2008
Publisher: AMER INST PHYSICS
Citation: JOURNAL OF APPLIED PHYSICS, 103(8), -
Abstract: GaN films have been deposited by reactive rf sputtering of GaAs target in 100% nitrogen ambient on quartz substrates at different substrate temperatures ranging from room temperature to 700 degrees C. A series of films, from arsenic-rich amorphous to nearly arsenic-free polycrystalline hexagonal GaN, has been obtained. The films have been characterized by phase modulated spectroscopic ellipsometry to obtain the optical parameters, viz., fundamental band gap, refractive index, and extinction coefficient, and to understand their dependence on composition and microstructure. A generalized optical dispersion model has been used to carry out the ellipsometric analysis for amorphous and polycrystalline GaN films and the variation of the optical parameters of the films has been studied as a function of substrate temperature. The refractive index values of polycrystalline films with preferred orientation of crystallites are slightly higher (2.2) compared to those for amorphous and randomly oriented films. The dominantly amorphous GaN film shows a band gap of 3.47 eV, which decreases to 3.37 eV for the strongly c-axis oriented polycrystalline film due to the reduction in amorphous phase content with increase in substrate temperature. (c) 2008
URI: http://dx.doi.org/10.1063/1.2903443
http://dspace.library.iitb.ac.in/xmlui/handle/10054/4459
http://hdl.handle.net/10054/4459
ISSN: 0021-8979
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