Taichiro Konno

Hydride vapor phase epitaxy for 6-inch GaN-on-GaN wafer production

Shota Kaneki, Taichiro Konno, Hisashi Mori, Hajime Fujikura et autres

Quartz-free hydride vapor phase epitaxy for production of large size GaN-on-GaN epitaxial wafers

Shota Kaneki, Taichiro Konno, Hisashi Mori, Hajime Fujikura

Abstract GaN-on-GaN epitaxial growth on 4 and 6 inch wafers was demonstrated using a new mass-production-type quartz-free hydride vapor phase epitaxy (QF-HVPE) system. The thickness, effective donor density, and near-band-edge photoluminescence peak intensity were confirmed to be uniform for 4 inch wafers. …

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Recent progress in HVPE-based GaN substrate fabrication

Hajime Fujikura, Taichiro Konno, Shota Kaneki, Masafumi Yokoyama et autres

Using our void-assisted separation (VAS) method based on hydride vapor phase epitaxy (HVPE), a 6-inch free-standing GaN wafer has been successfully realized. Extremely wide range of n-type doping from 1e15 to 1e20 /cm3 is available. High enough thermal conductivity around 150 W/mK, …

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Switching of major nonradiative recombination centers (NRCs) from carbon impurities to intrinsic NRCs in GaN crystals

Kazuhiro Sano, Hajime Fujikura, Taichiro Konno, Shota Kaneki et autres

The external quantum efficiency (EQE) and internal quantum efficiency (IQE) of radiation are quantified by omnidirectional photoluminescence measurements using an integrating sphere for two types of GaN crystals with different carbon concentrations ([C] = 1×1014 cm−3, 2×1015 cm−3). In the sample with …

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Fabrication of free-standing GaN substrates using electrochemically formed porous separation layers

Masafumi Yokoyama, Fumimasa Horikiri, Hisashi Mori, Taichiro Konno et autres

Abstract We have developed a pore-assisted separation (PAS) method for the fabrication of free-standing GaN substrates, where bulk GaN crystals were separated from seed GaN templates at electrochemically formed porous layers. The pore size was controlled by the electrochemical process conditions and …

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GaN and AlGaN epitaxy by HVPE

Hajime Fujikura, Taichiro Konno, Shota Kaneki

High-speed growth (>1um/min) of highly-pure homo-epitaxial GaN layers ([C], [O] < mid-1e14/cm3) suitable for a drift layer of vertical-type power device became possible by using a quartz-free HVPE. This highly pure GaN crystal exhibited a record high room temperature and low temperature …

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Record high electron mobilities in high-purity GaN by eliminating C-induced mobility collapse

Shota Kaneki, Taichiro Konno, Takeshi Kimura, Kazutaka Kanegae et autres

Impact of carbon impurities on the electrical properties of lightly doped n-type GaN [electron concentration ∼(1–2)×1015 cm−3 at room temperature] was investigated using temperature-dependent Hall effect measurements. GaN crystals with a threading dislocation density of (1–3)×106 cm−2 were grown by our originally …

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Fabrication of AlGaN/GaN heterostructures on halide vapor phase epitaxy AlN/SiC templates for high electron mobility transistor application

Masatomo Sumiya, Osamu Goto, Yuki Takahara, Y. Imanaka et autres

Abstract GaN films were grown on hydride vapor phase epitaxy (HVPE) AlN/SiC templates by metalorganic CVD (MOCVD) without annealing the reactor to eliminate the memory effect. A step-terrace structure and smooth surface were obtained for the GaN film, which had a thickness …

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Hydride vapor phase epitaxial growth of AlGaN

Hajime Fujikura, Taichiro Konno, Takeshi Kimura

Abstract The growth of AlGaN layers on GaN and AlN templates by hydride vapor phase epitaxy (HVPE) was experimentally investigated in detail. Linear control of the Al solid fraction with respect to that of the gas phase was established under conditions with …

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Fabrication and characterization of GaN-HEMT grown on AlN/SiC templates

Masatomo Sumiya, Osamu Goto, Liwen Sang, Yuki Takahara et autres

Substantial and simultaneous reduction of major electron traps and residual carbon in homoepitaxial GaN layers

Takeshi Kimura, Taichiro Konno, Hajime Fujikura

The presence of large amounts of electron traps together with residual carbon, as well as their trade-off relationship, is an obstacle to fabricating next-generation GaN-based power devices using the metal-organic chemical vapor deposition (MOCVD) method. Using the hydride vapor phase epitaxy (HVPE) …

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Homo-epitaxial growth of n-GaN layers free from carbon-induced mobility collapse and off-angle-dependent doping variation by quartz-free hydride vapor phase epitaxy

Hajime Fujikura, Taichiro Konno, Takeshi Kimura, Yoshinobu Narita et autres

Certain undesired phenomena are observed in n-GaN layers grown by metal–organic chemical vapor deposition (MOCVD) due to the unavoidable C-induced carrier compensation. They are a drastic reduction in carrier mobility, called mobility collapse, and significant non-uniformity in the carrier concentration due to …

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