The Experts below are selected from a list of 20922 Experts worldwide ranked by ideXlab platform
C J Humphreys - One of the best experts on this subject based on the ideXlab platform.
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improvements in a plane gan Crystal Quality by a two step growth process
Applied Physics Letters, 2008Co-Authors: J L Hollander, M J Kappers, C Mcaleese, C J HumphreysAbstract:Nonpolar (112¯0) a-plane GaN films have been grown by metal-organic vapor deposition on r-plane (11¯02) sapphire. Lateral growth is favored using a low V:III ratio resulting in films with a smooth surface, while pitted films are grown at a high V:III ratio indicating preferential on-axis growth. High-resolution x-ray diffraction analysis of both film types showed a strong anisotropy in the peak width of the symmetric omega rocking curve with respect to the in-plane orientation, phi. In-plane isotropic behavior of Crystallinity with overall reduced omega full width at half maximum values was achieved when the growth was initiated at a high V:III ratio before reducing the V:III ratio for film coalescence. An improvement of Crystal Quality through initial surface roughening was equally realized by the incorporation of partial-coverage SiNx interlayers.
Christiana Honsberg - One of the best experts on this subject based on the ideXlab platform.
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improvement of gap Crystal Quality and silicon bulk lifetime in gap si heteroepitaxy
Journal of Crystal Growth, 2017Co-Authors: Chaomin Zhang, Nikolai Faleev, Christiana HonsbergAbstract:Abstract The GaP Crystal Quality and Si bulk lifetime of GaP/Si heterostructures, grown by molecular beam epitaxy, are investigated. The Si bulk lifetime is reduced by over one order of magnitude after thermal deoxidation at high temperatures (>700 °C). This significant reduction of the bulk lifetime is not observed when 150 nm-thick SiN x film is present on the backside of Si wafer, which can act as a diffusion barrier and/or getter. In addition, a 15 nm-thick GaP layer grown on the front side of Si wafer with SiN x on the backside shows a high Crystal Quality of GaP with a low Crystalline defect density of 1.1 × 10 5 cm −2 . Moreover, the Si bulk lifetime is determined to be 1.83 ms with a-Si:H passivation at an injected minority-carrier density of 1 × 10 15 cm −3 , indicative of no bulk lifetime degradation. The high Crystallinity of GaP and improved Si bulk lifetime are beneficial to improve photovoltaic device performance of III–V compound solar cells integrated with Si solar cells.
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Improvement of GaP Crystal Quality and silicon bulk lifetime in GaP/Si heteroepitaxy
Journal of Crystal Growth, 2017Co-Authors: Chaomin Zhang, Nikolai Faleev, Christiana HonsbergAbstract:Abstract The GaP Crystal Quality and Si bulk lifetime of GaP/Si heterostructures, grown by molecular beam epitaxy, are investigated. The Si bulk lifetime is reduced by over one order of magnitude after thermal deoxidation at high temperatures (>700 °C). This significant reduction of the bulk lifetime is not observed when 150 nm-thick SiN x film is present on the backside of Si wafer, which can act as a diffusion barrier and/or getter. In addition, a 15 nm-thick GaP layer grown on the front side of Si wafer with SiN x on the backside shows a high Crystal Quality of GaP with a low Crystalline defect density of 1.1 × 10 5 cm −2 . Moreover, the Si bulk lifetime is determined to be 1.83 ms with a-Si:H passivation at an injected minority-carrier density of 1 × 10 15 cm −3 , indicative of no bulk lifetime degradation. The high Crystallinity of GaP and improved Si bulk lifetime are beneficial to improve photovoltaic device performance of III–V compound solar cells integrated with Si solar cells.
Weichih Liao - One of the best experts on this subject based on the ideXlab platform.
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improved Crystal Quality and performance of gan based light emitting diodes by decreasing the slanted angle of patterned sapphire
Applied Physics Letters, 2010Co-Authors: Jihao Cheng, Yewchung Sermon Wu, Weichih LiaoAbstract:Periodic triangle pyramidal array patterned sapphire substrates (PSSs) with various slanted angles were fabricated by wet etching. It was found beside normal wurtzite GaN, zinc blende GaN was found on the sidewall surfaces of PSS. The Crystal Quality and performance of PSS-LEDs improved with decrease in slanted angle from 57.4° to 31.6°. This is because most of the growth of GaN was initiated from c-planes. As the growth time increased, GaN epilayers on the bottom c-plane covered these pyramids by lateral growth causing the threading dislocation to bend toward the pyramids.
J L Hollander - One of the best experts on this subject based on the ideXlab platform.
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improvements in a plane gan Crystal Quality by a two step growth process
Applied Physics Letters, 2008Co-Authors: J L Hollander, M J Kappers, C Mcaleese, C J HumphreysAbstract:Nonpolar (112¯0) a-plane GaN films have been grown by metal-organic vapor deposition on r-plane (11¯02) sapphire. Lateral growth is favored using a low V:III ratio resulting in films with a smooth surface, while pitted films are grown at a high V:III ratio indicating preferential on-axis growth. High-resolution x-ray diffraction analysis of both film types showed a strong anisotropy in the peak width of the symmetric omega rocking curve with respect to the in-plane orientation, phi. In-plane isotropic behavior of Crystallinity with overall reduced omega full width at half maximum values was achieved when the growth was initiated at a high V:III ratio before reducing the V:III ratio for film coalescence. An improvement of Crystal Quality through initial surface roughening was equally realized by the incorporation of partial-coverage SiNx interlayers.
Takatomo Sasaki - One of the best experts on this subject based on the ideXlab platform.
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Enhancement of the CsB3O5(CBO) Crystal Quality by fast cooling after Crystal growth
Journal of Crystal Growth, 2011Co-Authors: Zengmei Wang, Dodla Rajesh, Masashi Yoshimura, Hiroya Shimatani, Yusuke Kitaoka, Yusuke Mori, Takatomo SasakiAbstract:CsB3O5(CBO) is an excellent nonlinear optical Crystal and can be grown by top-seeded solution growth (TSSG) from self-flux solutions. However, there are scattering centers in the as-grown Crystal, which decrease the bulk laser-induced damage threshold (LIDT) of the Crystal. Postgrowth quenching and vapor transport equilibration (VTE) can reduce the scattering centers effectively. Based on our previous hypothesis and analysis of retrograde solid solution at high temperature in CBO Crystal, we adopt selective quenching to 500 °C - fast cooling. Our investigations showed that, after the cooling process, the scattering centers and optical loss of CBO were decreased. It was found that with the increase in cooling rate, the LIDT of CBO Crystals was increased. The highest LIDT of fast cooling CBO was 1.5 times that of conventional cooling process; so the Crystal Quality was improved. © 2010 Elsevier B.V. All rights reserved.
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Enhancement of CsB3O5(CBO) Crystal Quality
2009 Conference on Lasers & Electro Optics & The Pacific Rim Conference on Lasers and Electro-Optics, 2009Co-Authors: Zengmei Wang, Dodla Rajesh, Masashi Yoshimura, Hiroya Shimatani, Yusuke Kitaoka, Yusuke Mori, T. Kawamura, Takatomo SasakiAbstract:CsB3O5 (CBO) is an excellent nonlinear optical Crystal and can be grown by top-seeded solution growth (TSSG) from self flux solutions. In this research, Crystals with different cooling rates were grown to attempt to improve the Crystal Quality. Our investigations showed that, after cooling process, the scattering centers and optical loss of CBO were decreased. The bulk laser-induced damage threshold (LIDT) was found to be 1.5 times that of conventional cooling process.