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Metalorganic Vapor Phase Epitaxy (metalorganic + vapor_phase_epitaxy)
Selected AbstractsDevelopment of InN metalorganic vapor phase epitaxy using in-situ spectroscopic ellipsometryCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10-11 2005M. Drago Abstract Metalorganic vapor phase epitaxy of InN layers on sapphire was studied in-situ by spectroscopic ellipsometry (SE), ex-situ atomic force microscopy and optical microscopy. Surface morphology has been largely improved by using nitrogen instead of hydrogen as carrier gas during sapphire nitridation. Using the sensitivity of in-situ SE with respect to roughness we established a new growth procedure with low V/III ratio (104) at high temperature (580 °C) and growth rates as high as 350 nm/h, leading to improved electronic layer properties and allowing for growth of comparably thick layers. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optimization of homoepitaxially grown AlGaN/GaN heterostructuresPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2010J. A. Grenko Abstract We report on the growth of Al0.25Ga0.75N/GaN heterostructures on low dislocation density semi-insulating c -axis GaN substrates by metalorganic vapor phase epitaxy (MOVPE). A room temperature (RT) Hall mobility (µRT) up to 2065,cm2,V,1,s,1 at sheet density (ns) of 8.25,×,1012,cm,2 has been measured. This work compliments prior studies in which we observed a buffer-induced modulation of the RT two-dimensional electron gas (2DEG) ns and µRT by varying the GaN buffer layer thickness. Here, we focus on the optimization of the heterostructure 2DEG properties by elimination of silicon doping in the Al0.25Ga0.75N barrier and unintentional Al in the not-intentionally doped (n.i.d.) GaN buffer layer. The 15% improvement in µRT and ns relative to previous results is consistent with those predicted by Poisson solver calculations. Use of thick GaN buffers has minimized the theoretical mobility reduction based on intersubband scattering and has enabled us to determine the 2DEG sheet density associated with the polarization field () to be ,5,×,1012,cm,2. [source] AlInN HEMT grown on SiC by metalorganic vapor phase epitaxy for millimeter-wave applicationsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2010Shiping Guo Abstract In this work we present the epitaxial and device results of AlInN/GaN HEMTs grown on SiC by metalorganic vapor phase epitaxy. High quality AlInN/GaN HEMT structures with sub-10,nm AlInN barrier were grown with very low Ga background level (<1%). The low Rsh of 215,,/sq was obtained with an excellent standard deviation of 1.1% across 3, wafers. Lehighton RT contactless Hall tests show a high mobility of 1617,cm2/V,s and sheet charge density of 1.76,×,1013/cm2. DC characteristics of an AlInN/GaN HEMT with a gate length of 0.1,µm and 25,nm Al2O3 passivation show maximum drain current (IDS,max) of 2.36,A/mm at VGS,=,2,V. Gate recessed devices with 0.15,µm gate length and 25,nm Al2O3 passivation resulted in maximum transconductance (gm) of 675,mS/mm, the highest value ever reported in AlInN transistors. Excellent frequency response was obtained. The maximum fT is 86,GHz and fmax is 91.7,GHz. [source] Nitride-based quantum structures and devices on modified GaN substratesPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2009Piotr Perlin Abstract We have studied the properties of InGaN layers and quantum wells grown on gallium nitride substrates with intentional surface misorientation with respect to its crystalline c -axis. Misorientation varied in the range from 0 up to 2 degree. The indium content was changed by using the different growth temperature (between 750 °C and 820 °C) during metalorganic vapor phase epitaxy. With increasing misorientation angle the average indium content decreased significantly. This effect was accompanied by the strong increase of the emission line bandwidth suggesting more pronounced indium segregation. The results of cathodoluminescence measurements show that these effects correspond to different number of atomic steps/terraces existing on the surface of gallium nitride substrate. Very interesting result is also demonstrated concerning p-type GaN layers. With increasing misorientation, the free hole density drastically increases above 1018 cm,3. This improvement in p-type doping is not related to the increased Mg concentration but to the reduction in the compensating donor density. Using this advantage we demonstrate nitride light emitters with improved electrical properties. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] On the way to InGaN quantum dots embedded into monolithic nitride cavitiesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 6 2007K. Sebald Abstract We present photoluminescence measurements on single InGaN quantum dots (QDs) grown by metalorganic vapor phase epitaxy, and on monolithicly grown GaN-based quantum well airpost pillar microcavities. The observed sharp emission lines of the quantum dots are characterized by excitation density dependent measurements. The photoluminescence of individual quantum dots can easily be detected for temperatures up to 150 K. The micro-photoluminescence measurements on microcavities reveal three-dimensional confined optical modes which are not seen in the luminescence of the simply planar cavity. The realization of rather temperature stable QDs as well as of nitride based microcavity samples are promising with respect to the intended implementation of QD layers into microcavities. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The influence of aluminum composition of AlxGa1,xAs in distributed Bragg reflector on surface morphologyPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 12 2004B. Kim Abstract Surface morphology of the AlGaAs/GaAs Vertical Cavity Surface Emitting Laser (VCSEL) grown by metalorganic vapor phase epitaxy (MOVPE) was investigated using atomic force microscopy. It is shown that the morphology of the structure strongly depends on the aluminum composition of the low Al content layer of distributed Bragg reflector (DBR) pairs and epi thickness. Whereas a high Al content layer in DBRs had little effect on the surface morphology, it was attributed that the influence of Al composition on the morphology of AlxGa1,xAs on GaAs was stronger in the range of 0 < x < 0.5 than 0.5 < x < 1. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth of GaN on a -plane sapphire: in-plane epitaxial relationships and lattice parametersPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2003T. Paskova Abstract We have studied GaN films grown on a -plane sapphire substrates by both hydride vapor phase epitaxy (HVPE) and metalorganic vapor phase epitaxy (MOVPE). The in-plane orientation relationships between the epitaxial films and the substrate are determined to be [11,20]GaN , [0001]sapphire and [1,100]GaN , [1,100]sapphire in the HVPE growth, while [1,100]GaN , [0001]sapphire and [11,20]GaN , [1,100]sapphire are found in the MOVPE growth. The different orientation preferences are attributed to the atom termination of the sapphire surface determined by the substrate treatment used in the different growth methods. The effect of the lattice matches on the in-plane lattice parameters and strain anisotropy in the two cases is studied. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Sidewall epitaxial lateral overgrowth of nonpolar a-plane GaN by metalorganic vapor phase epitaxyPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008Daisuke Iida Abstract A major obstacle to achieving high-performance devices using nonpolar a-plane and m-plane GaN is the existence of high-density threading dislocations and stacking faults. Low-defect-density nonpolar plane GaN films were previously grown by sidewall epitaxial overgrowth using metalorganic vapor phase epitaxy [1, 2]. In this study, we control the growth-rate ratio of Ga-polar GaN to N-polar GaN by adjusting the V/III ratio. It is possible to grow GaN only from the N-face sidewall of grooves by maintaining a high V/III ratio, which reduces the number of coalescence regions on grooves and decreases the threading-dislocation density and stacking-fault density. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optimization of underlying layer and the device structure for group-III-nitride-based UV emitters on sapphirePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008K. Iida Abstract Epitaxial lateral overgrowth (ELO) was applied for the growth of AlGaN on a sapphire substrate by metalorganic vapor phase epitaxy. Among several processes, the ELO of AlGaN on grooved AlGaN showed the best surface morphology and the lowest dark-spot density of 1×108 cm,2 as measured using cathodoluminescence. The light output power of a UV LED fabricated on ELO-Al0.25Ga0.75N on grooved Al0.25Ga0.75N was the strongest among several UV LEDs fabricated by different processes. The effect of the Al composition in the electron-blocking (EB) layer on the performance of UV LEDs was investigated. The UV LED with a low-Al-content EB layer showed high output power under a low-injection condition, while the output power of a UV LED with a high-Al-content EB layer did not saturate even under a high-injection condition. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The surface diffusion of Ga species on an AlGaN facet structure in low pressure MOVPEPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2007Tetuso Narita Abstract The diffusion of Ga species in gas phase as well as on the surface are studied in selective area growth of AlGaN in low pressure metalorganic vapor phase epitaxy. The experiments were performed on a trapezoidal stripe with (0001) facet on the top and (1-101) facet on the sides. It was found that the ridge growth on the facets were sensitive to the growth pressure, in agreement with numerical results. At a low pressure of 100 Torr, we got a uniform thickness of AlGaN alloy, but the alloy composition was not uniform. Exponential variation of the composition gave the effective diffusion length of Ga on the order of 0.7 ,m which was independent of the growth pressure. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Investigations on local Ga and In incorporation of GaInN quantum wells on facets of selectively grown GaN stripesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006B. Neubert Abstract Multiple GaInN quantum wells (QWs) were grown on side facets with reduced piezoelectric fields (PFs) of selectively grown GaN stripes oriented along the ,100, and ,110, directions by metalorganic vapor phase epitaxy (MOVPE). The different luminescence wavelengths observed for the QWs on these facets can be explained by the reduced PFs, additionally the QW thickness depends on the facet type. Although stripes running along ,100, and ,110, develop similar triangular or trapezoidal shape, their detailed growth behaviour, electrical and luminescence properties differ significantly pointing to different adsorption/desorption and inter-facet migration processes of In, Ga and the p-type dopant Mg. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Cathodoluminescence and electrophysical characterization of AlxGa1,xN epilayersPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006V. I. Kozlovsky Abstract Cathodoluminescence (CL) of metalorganic vapor phase epitaxy (MOVPE) grown AlxGa1,xN epilayers on sapphire has been studied with x from 0.23 to 0.38. CL spectra of undoped and Si-doped AlGaN epilayers with the same alloy composition grown on thick GaN buffers have been compared. The free electron concentration in the doped samples has been measured to (1-1.6) × 1017 cm,3 with a mobility of 84-115 cm2/Vs. CL spectra have been compared with deep level transient spectroscopy spectra. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Advanced buffers for AlGaN/GaN HEMT and InGaN/GaN MQW on silicon substratesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2006Y. Dikme Abstract GaN growth was carried out on silicon (Si) substrates by metalorganic vapor phase epitaxy (MOVPE). A layer structure starting with HT (high-temperature) AlN and containing AlGaN and GaN as interlayers was employed for the subsequent deposition of GaN buffer layers. At first, the influence of the in-situ Al pre-deposition at the process start with different durations was investigated. Each time, the pre-deposition was followed by the same layer sequence and with thin AlGaN and GaN grown on top to form a high electron mobility transistor (HEMT). A significant enhancement could be observed in the properties of the investigated samples by reducing the pre-deposition time from 8 s to 2 s. Based on these results, multiple quantum well structures (MQW) and HEMT were grown on these buffers. For the MQW, the well thickness was increased and a shift to higher wavelengths was observed. The HEMT structures have shown enhanced properties by optimizing the growth temperatures of the top AlGaN layer. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Improved crystallinity and polarity manipulation of MOVPE-grown GaN epilayers with deep sapphire-nitridation followed by Al-preflow at high temperaturesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2003B. W. Seo Abstract The polarity manipulation and crystallinity of GaN epilayers grown by metalorganic vapor phase epitaxy (MOVPE) on deeply nitrided c -sapphire was studied by using TMAl preflow at high temperatures (HT-TMAl preflow) of 1100 °C. It was found that the HT-TMAl preflow was very effective to change the surface polarity; the successful change to Ga-polarity from N-polarity and the atomic-steps were observed when the Al layer thickness was above two-monolayers, though it was remained N-polarity without the Al layer. The crystallinity of GaN epilayer is increased using HT-TMAl preflow. High quality Ga-polarity GaN epilayers was grown by this technique and typical full width at half maximums (FWHMs) for X-ray rocking curves were 300,320 arcsec and 450,480 arcsec for (002) and (102) diffractions, respectively. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth and characterization of ZnGeN2 by using remote-plasma enhanced metalorganic vapor phase epitaxyPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2003T. Misaki No abstract is available for this article. [source] HVPE Growth of GaN on a GaN Templated (111) Si SubstratePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2003Y. Honda Abstract The hydride vapor phase epitaxial (HVPE) growth of GaN was attempted on a (111) Si substrate. In order to suppress the chemical reaction of the Si at high temperatures, the surface of the substrate was covered by a thin SiO2 film or GaN pyramids which were grown by selective metalorganic vapor phase epitaxy (MOVPE). The GaN pyramids served as the seeds for the following HVPE growth of GaN. Uniform layer of 12 ,m thick wurtzite GaN was achieved successfully. The full width at half maximum (FWHM) of (0004) X-ray rocking curve was 450 arcsec. The cathode luminescence (CL) spectra at 4.2 K exhibited a strong band edge emission peak of which FWHM was as broad as 30.3 meV. [source] | ||||||||||