Fundamental properties of Indium Nitride thin films
Date Issued
2006
Date
2006
Author(s)
Fu, Szu-Ping
DOI
en-US
Abstract
Up to the very recently, InN has been the least studied of the group Ⅲ-nitride semiconductors. In this thesis, detailed optical and transport properties of high-quality InN thin films grown by molecular beam expitaxy and metal organic chemical vapor deposition were investigated. Combining with model calculations, we provide a deeper understanding of physical properties of this material. For optical properties, we found that the photoluminescence transition mechanism in InN epifilms can be characterized as the recombination of free electrons in the conduction band to nonequilibrium holes in the valence band tail. The band gap energy at zero temperature and room temperature are 0.68 eV and 0.62 eV, respectively. The temperature dependence of the band gap energy can be well described by the Pässler equation and the parameters of intrinsic InN are α=0.55 meV K-1, Θ=576 K, and p=2.2. For transport properties, we found that the electron effective mass increases with increasing free electron concentration. Calculations based on the combination of Kane’s model and band renormalization effect due to electron-electron interaction and electron-ionized impurity interaction can provide excellent description. The effective mass at the bottom of the conduction band was found to be m* =0.05 m0, which is in good agreement with the theoretical calculation. Finally, surface morphologies, transport and optical properties of hydrogenated InN epifilms were also investigated. The average rms surface roughness decreases after hydrogenation. The free electron concentration can be increased or decreased depending on the duration of hydrogenation. The linewidth of the photoluminescence spectra can be reduced, and the peak intensity can be enhanced by about three times. These results indicated the physical properties of InN films can be improved by hydrogenation. Possible origins of the underlying mechanism have been proposed to explain the improvement.
Subjects
氮化銦
能隙
有效質量
復合機制
InN
band gap
effective mass
recombination mechanism
Type
thesis
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