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Visible-Ultraviolet Spectroscopic Ellipsometry Of Lead Zirconate Titanate Thin Films, Hosun Lee, Youn Seon Kang, Sang-Jun Cho, Bo Xiao, Hadis Morkoç, Tae Dong Kang
Visible-Ultraviolet Spectroscopic Ellipsometry Of Lead Zirconate Titanate Thin Films, Hosun Lee, Youn Seon Kang, Sang-Jun Cho, Bo Xiao, Hadis Morkoç, Tae Dong Kang
Electrical and Computer Engineering Publications
We measured pseudodielectric functions in the visible-ultraviolet spectral range of Pb(ZrxTi1−x)O3 (x=0.2, 0.56, 0.82) (PZT)grown on platinized silicon substrate using the sol-gel method and also on (0001) sapphire using radio frequency sputtering method. Using a parametric optical constant model, we estimated the dielectric functions of the PZTthin films. Taking the second derivative of the fitted layer dielectric functions and using the standard critical point model, we determined the parameters of the critical points. In the second derivative spectra, the lowest bandgap energy peak near 4eV is fitted as a double peak for annealedPZTs associated with the perovskite phase. As-grown PZTs …
Dielectric Functions And Electronic Band Structure Of Lead Zirconate Titanate Thin Films, Hosun Lee, Youn Seon Kang, Sang-Jun Cho, Bo Xiao, Hadis Morkoç, Tae Dong Kang, Ghil Soo Lee, Jingbo Li, Su-Huai Wei, P. G. Snyder, J. T. Evans
Dielectric Functions And Electronic Band Structure Of Lead Zirconate Titanate Thin Films, Hosun Lee, Youn Seon Kang, Sang-Jun Cho, Bo Xiao, Hadis Morkoç, Tae Dong Kang, Ghil Soo Lee, Jingbo Li, Su-Huai Wei, P. G. Snyder, J. T. Evans
Electrical and Computer Engineering Publications
We measure pseudodielectric functions in the visible-deep ultraviolet spectral range of Pb(ZrxTi1−x)O3 (x=0.2,0.56,0.82) (PZT), Pb0.98Nb0.04 (Zr0.2Ti0.8)0.96O3, Pb0.91La0.09 (Zr0.65Ti0.35)0.98O3, and Pb0.85La0.15Ti0.96O3 films grown on platinized silicon substrates using a sol-gel method and on (0001) sapphire using a radio-frequency sputtering method. Using a parametric optical constant model, we estimate the dielectric functions(ϵ) of the perovskite oxide thin films. Taking the second derivative of the fitted layer dielectric functions and using the standard critical-point model, we determine the parameters of the critical points. In the second derivative spectra, the lowest band-gapenergy peak near 4 eVis fitted as a double peak for annealed PZTs …
Characterization Of Ingan/Gan Multi-Quantum-Well Blue-Light-Emitting Diodes Grown By Metal Organic Chemical Vapor Deposition, K. S. Ramaiah, Y. K. Su, S. J. Cheng, B. Kerr, H. P. Liu, I. G. Chen
Characterization Of Ingan/Gan Multi-Quantum-Well Blue-Light-Emitting Diodes Grown By Metal Organic Chemical Vapor Deposition, K. S. Ramaiah, Y. K. Su, S. J. Cheng, B. Kerr, H. P. Liu, I. G. Chen
Electrical and Computer Engineering Publications
The structural,surface morphology, and the temperature dependence photoluminescence of InGaN(3 nm)/GaN(7 nm) 5 period multi-quantum-well blue-light-emitting diode (LED)structures grown by metal organic chemical vapor deposition(MOCVD) have been studied. Quantum dot-likestructures and strain contrast evident by black lumps were observed in the quantum wells using high-resolution transmission electron microscopy(HRTEM) analysis. Double-crystal high-resolution x-ray diffraction (HRXRD) spectra of blue LED were simulated using kinematical theory method, to obtain composition, and period thickness of well and barrier. The “S” shape character shift as red–blue–redshift of the quantum-well emission line, i.e., blue emission peak 2.667 eV at 10 K, was observed with variation of …
Well-Width Dependence Of The Ground Level Emission Of Gan/Algan Quantum Wells, A. Bonfiglio, M. Lomascolo, G. Traetta, R. Cingolani, A. Di Carlo, F. Della Sala, P. Lugli, A. Botchkarev, H. Morkoç
Well-Width Dependence Of The Ground Level Emission Of Gan/Algan Quantum Wells, A. Bonfiglio, M. Lomascolo, G. Traetta, R. Cingolani, A. Di Carlo, F. Della Sala, P. Lugli, A. Botchkarev, H. Morkoç
Electrical and Computer Engineering Publications
We have performed a systematic investigation of GaN/AlGaN quantum wells grown on different buffer layers (either GaN or AlGaN) in order to clarify the role of strain, structural parameters, and built-in field in determining the well-width dependence of the ground level emission energy. We find that identical quantum wells grown on different buffer layers exhibit strong variation of the ground level energy but similar well-width dependence. The data are quantitatively explained by an analytic model based on the envelope function formalism which accounts for screening and built-in field, and by a full self-consistent tight binding model.