Results 1 - 10 of 1888
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[en] Due to the remarkable growth rate compared to another growth methods for gallium nitride (GaN) growth, hydride vapor phase epitaxy (HVPE) is now the only method for mass product GaN substrates. In this review, commercial HVPE systems and the GaN crystals grown by them are demonstrated. This article also illustrates some innovative attempts to develop homebuilt HVPE systems. Finally, the prospects for the further development of HVPE for GaN crystal growth in the future are also discussed. (paper)
[en] A 0.09 mm m-plane GaN film is deposited via hydride vapor phase epitaxy (HVPE) on a γ-LiAlO2 substrate. To research the anisotropy between directions with different angles with the c-axis in the m plane, photoluminescence (PL) measurements were carried out. The results show that the electronic transition was influenced by the electric field along the c-axis, which results in an obvious anisotropy, but the influence was weakened by the hexagonal symmetry along the c-axis.
[en] A 100-μm-long electroabsorption modulator monolithically integrated with passive waveguides at the input and output ports is fabricated through ion implantation induced quantum well intermixing, using only a two-step low-pressure metal-organic vapor phase epitaxial process. An InGaAsP/InGaAsP intra-step quantum well is introduced to the active region to improve the modulation properties. In the experiment high modulation speed and high extinction ratio are obtained simultaneously, the electrical-to-optical frequency response (E/O response) without any load termination reaches to 22 GHz, and extinction ration is as high as 16 dB.
[en] Epitaxial-grade polycrystalline Pb(Zr,Ti)O3 (PZT) films were deposited at 415oC by source- gas-pulsed-introduced metalorganic chemical vapor deposition. The polycrystalline PZT film with Zr/(Zr+Ti)=0.35 which was prepared on (111)Pt/Ti/SiO2/Si substrate showed highly (100)- and (001)-preferred orientations. Well-saturated ferroelectricity with a remanent polarization (Pr) and coercive field of 41.4 μC/cm2 and 78.5 kV/cm, respectively, was obtained. This Pr value is almost the same as that of epitaxially grown films at 580oC with the same composition and orientations taking into account of the volume fraction of (100) and (001) orientations. Copyright 2001 American Institute of Physics
[en] In this letter, we report on the growth and the properties of freestanding GaN substrates. Large areas of one-inch square with a thickness of a 0.5 mm were grown by the hydride vapor-phase epitaxy (HVPE) method after a thick film of GaN was grown on an AIN buffer layer deposited on a sacrificial Si substrate which was subsequently chemically removed. The GaN substrate showed intensified X-ray diffraction from the (00.2) and the (00.4) planes, and the full width at half maximum of the double-crystal X-ray diffraction curve was as large as 4.2 degrees. The photoluminescence spectra measured at 10 K and at 300 K exhibited a sharp and strong excitonic emission without deep-level emission. They also showed n-type conduction with an electron concentration of ∼1x1018 cm -3 and a Hall mobility of 50 cm2 / Vsec. The highly c-axis oriented large-area freestanding GaN prepared using a Si sacrificial substrate by HVPE through this work can be used for homoepitaxial growth of GaN-based optoelectronic devices
[en] The thin layers of hexagonal boron nitride (hBN) are very similar to graphene, with hexagonal rings of alternating boron and nitrogen atoms. Sapphire-supported thin hBN films of different thicknesses are grown using metalorganic vapour phase epitaxy technique. During the growth process, the differential thermal expansion coefficient of hBN and sapphire results in a strain in the films; this is partially released by wrinkling. The talk will focus on the mapping of residual strain in the films and possibility of obtaining strain free films by thermal treatment using Raman imaging. (author)
[en] The paper reviews metal-organic vapor phase epitaxy (MOVPE) of some key elements of III-N devices: InGaN quantum wells, InGaN/GaN and Al(Ga)N/GaN short-period superlattices, AlGaN/GaN and InAlN/GaN distributed Bragg reflectors. It is demonstrated that interaction of III-N materials with hydrogen is one of the key processes in MOVPE of these materials. Depending on the desired structure, this process may be fruitfully used or should be suppressed by the proper adjustment of reactor conditions
[en] Epitaxial growth of GaN(0 0 0 1) is possible even using molecular beam epitaxy (MBE). Under the N-rich condition, nitrogen adatom on GaN(0 0 0 1) truncated surface adsorbed at an abnormal site, H3-site which is not the original site for wurtzite structure nor zincblende structure. The nitrogen at the H3-site is very stable and inactive so that the epitaxial growth is prevented. The first-principles calculation shows us that the Ga-rich condition is very helpful to assist epitaxial growth of GaN(0 0 0 1)
[en] In the Si3N4 layer, coaxial and single submicrometer GaN structures of hexagonal shape with pyramidal facets are formed by selective vapor-phase epitaxy in windows produced with a focused ion beam. It is found that coaxial hexagonal structures are formed during the growth process in ring-shaped mask windows.