NAOI Yoshiki

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Name
NAOI Yoshiki
Affiliation
The University of Tokushima
Section
Institute of Technology and Science
Job title
Associate Professor
Degree
(BLANK)

Research Areas

 
 

Education

 
 
 - 
1993
Graduate School, Division of Engineering, Tohoku University
 
 
 - 
1988
Faculty of Engineering, The University of Tokushima
 

Misc

 
Yuusuke Takashima, Masato Tanabe, Masanobu Haraguchi, Masanobu Haraguchi, Yoshiki Naoi, Yoshiki Naoi
Optics Communications   369 38-43   Jun 2016
© 2016 Elsevier B.V. All rights reserved.The polarization characteristics of a 370 nm GaN-based ultraviolet light-emitting diode (UV-LED) were controlled by a subwavelength grating (SWG) on a low-refractive-index SiO2 underlayer inserted between t...
Taofei Pu, Jing Zhang, Jing Zhang, Zhongliang Qiao, Yoshiki Naoi, Yoshiki Naoi, Shiro Sakai, Shiro Sakai
2015 International Conference on Optoelectronics and Microelectronics, ICOM 2015   365-368   Feb 2016
© 2015 IEEE.In this study, Nanostructure devices were fabricated from the wafer with LED structure grown by metal organic chemical vapor deposition (MOCVD). A GaN-based nanostructure photodetector has been made using nanoimprint lithography (NIL) ...
Yuusuke Takashima, Ryo Shimizu, Masanobu Haraguchi, Masanobu Haraguchi, Yoshiki Naoi, Yoshiki Naoi
Optical Engineering   54    Jun 2015
© 2015 Society of Photo-Optical Instrumentation Engineers (SPIE).We analytically investigated the influence of grating shape on polarization characteristics of the emission from a GaN-based light-emitting diode with a low-contrast subwavelength gr...
Yun Jeong Choi, Yoshiki Naoi, Yoshiki Naoi, Takuro Tomita, Takuro Tomita
Japanese Journal of Applied Physics   54    Jan 2015
© 2015 The Japan Society of Applied Physics.Highly ordered honeycomb buckling patterns were self-organized by a simple annealing process. The patterns were formed by thin, layered crystalline films of Al4C3 and carbon synthesized on a sapphire c-p...
Yuusuke Takashima, Ryo Shimizu, Masanobu Haraguchi, Masanobu Haraguchi, Yoshiki Naoi, Yoshiki Naoi
Japanese Journal of Applied Physics   53    Jan 2014
We investigated polarized emission from a GaN-based ultraviolet light-emitting diode (UV-LED) with a subwavelength grating (SWG) on the surface. The electroluminescence (EL) spectra showed that the UV-LED exhibits high polarization selectivity, as...
Manato Deki, Manato Deki, Tomoki Oka, Shodai Takayoshi, Yoshiki Naoi, Takahiro Makino, Takeshi Ohshima, Takuro Tomita
Materials Science Forum   778-780 661-664   Jan 2014
Temperature dependence of the femtosecond laser modified region on silicon carbide was measured. The current-voltage characteristics showed the ohmic properties and thus we could evaluate the specific resistance for each irradiation condition and ...
Yuusuke Takashima, Ryo Shimizu Masanobu Haraguchi, Yoshiki Naoi
Technical Digest of the 18th Microoptics Conference, MOC 2013      Dec 2013
Subwavelength grating structure with a thickness of 150nm was fabricated on ultraviolet light emitting diode by using electron beam lithography and inductively coupled plasma (ICP) etching. For an optimal designed period, the subwavelength grating...
Shigeki Matsuo, Keiji Oda, Yoshiki Naoi
Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest      Oct 2013
Three dimensional micro removal processing was attempted to crystalline silicon substrate using a 1.56-μm subpicosecond laser. Selective removal was observed on both top and rear surfaces when nitric hydrofluoric acid was used as etchant. © 2013 I...
Dohyung Kim, Heesub Lee, Kazuya Yamazumi, Yoshiki Naoi, Shiro Sakai
Japanese Journal of Applied Physics   52    Aug 2013
A C-doped p-AlGaInN light-emitting diode (LED) fabricated from III-V nitride was grown by metalorganic vapor phase epitaxy (MOVPE) by the insertion of Al4C3/Al2O3(0001). A l4C3/Al2O3(0001) with a size of 1 ± 1mm2 was placed at the center of a 2-in...
Jin Ping Ao, Yoshiki Naoi, Yasuo Ohno
Vacuum   87 150-154   Jan 2013
© 2012 Elsevier Ltd.Evaluation of electrical performance of AlGaN/GaN heterostructure field-effect transistors (HFETs) with titanium nitride (TiN) gate and its thermal stability was presented. The TiN film was formed by reactive sputtering in Ar a...
Tianya Tan, Mitsuaki Tohno, Masakazu Matsumoto, Yoshiki Naoi, Shiro Sakai
Journal Wuhan University of Technology, Materials Science Edition   27 1137-1138   Dec 2012
A 385 nm InGaN/GaN LED on the sapphire with the nano-pattern was fabricated and its electroluminescence property was investigated in a three-dimensional (3D) space. The experimental results showed that the luminescent intensity of the LED was obvi...
Jing Zhang, Yoshiki Naoi, Shiro Sakai, Atsuyuki Fukano, Satoru Tanaka
Physica Status Solidi (C) Current Topics in Solid State Physics   7 1804-1806   Aug 2010
The conventional photodetector can detect the intensity of the incident light by the voltage or current, but it is not sensitive to the change of the incident angle or wavelength. A GaN-based photodetector with nanostructure on the surface has bee...
Yoshiki Naoi, Masakazu Matsumoto, Tianya Tan, Tianya Tan, Mistuaki Tohno, Shiro Sakai, Atsuyuki Fukano, Satoru Tanaka
Physica Status Solidi (C) Current Topics in Solid State Physics   7 2154-2156   Aug 2010
We investigated the characteristics of GaN-based light emitting diodes (LEDs) with periodic nano-structures on the surface by nanoimprint lithography technique. We measured the intensity emitted through nano-structure on the p-GaN surface into the...
Yuji Nariyuki, Masakazu Matsumoto, Takeshi Noda, Katsushi Nishino, Yoshiki Naoi, Shiro Sakai, Atsuyuki Fukano, Satoru Tanaka
Physica Status Solidi (C) Current Topics in Solid State Physics   7 2121-2123   Aug 2010
p-GaN were grown on a nano-patterned n-GaN fabricated by nanoimprint lithography (NIL). Originality of this paper is to grow the p-GaN layer on a nano-patterned GaN. The re-growth mechanism of p-GaN on nano-processing n-GaN was identified. The car...
Jin Ping Ao, Asato Suzuki, Kouichi Sawada, Satoko Shinkai, Yoshiki Naoi, Yasuo Ohno
Vacuum   84 1439-1443   Jun 2010
Schottky contacts of refractory metal nitrides formed by reactive sputtering on n-type gallium nitride (GaN) were electrically evaluated, including film resistivity, Schottky characteristics and thermal stability. For the metal nitrides of TiN ...
Jing Zhang, Yoshiki Naoi, Shiro Sakai, Atsuyuki Fukano, Satoru Tanaka
Japanese Journal of Applied Physics   48    Dec 2009
The photovoltage from a surface nanostructure photodetector was measured at wavelengths of 410 and 388 nm as a function of incident angle. Nanostructure devices were fabricated from the wafer with the light-emitting diode (LED) structure grown by ...
R. Matsuoka, T. Okimoto, K. Nishino, K. Nishino, Y. Naoi, Y. Naoi, S. Sakai, S. Sakai
Journal of Crystal Growth   311 2847-2849   May 2009
AlGaN growth using epitaxial lateral overgrowth (ELO) by metalorganic chemical vapor deposition on striped Ti, evaporated GaN on sapphire, has been investigated. AlGaN/AlN films growth on GaN/AlGaN superlattices (SLs) structure on the Ti masks, wi...
Y. Naoi, Y. Naoi, K. Ikeda, T. Hama, K. Ono, R. Choi, T. Fukumoto, K. Nishino, K. Nishino, S. Sakai, S. Sakai, S. M. Lee, M. Koike
Physica Status Solidi (C) Current Topics in Solid State Physics   4 2810-2813   Dec 2007
We studied the growth technique for the dislocation reduction in a-plane GaN grown by metal organic chemical vapour deposition (MOCVD) using AlInN buffer layer, high temperature atomic layer epitaxy, and trenched r-sapphire technique. By using the...
Mamiko Yamamoto, Yuta Hamazaki, Masashi Tsukihara, Yoshiki Naoi, Yoshiki Naoi, Katsushi Nishino, Katsushi Nishino, Shiro Sakai, Shiro Sakai
Japanese Journal of Applied Physics, Part 2: Letters   46    Apr 2007
BP with the size of 50 μm to 3 mm was synthesized by the Cu flux method. The BP crystals have a zincblend structure, and the lattice constant and the cathodoluminescence peak wavelength were 4.557 Å and 370 nm, respectively. GaN and AlN were grown...
M. Tsukihara, K. Sumiyoshi, T. Okimoto, K. Kataoka, S. Kawamichi, K. Nishino, K. Nishino, Y. Naoi, Y. Naoi, S. Sakai, S. Sakai
Journal of Crystal Growth   300 190-193   Mar 2007
We investigated the effect of a middle temperature intermediate layer (MTIL) of AlGaN and AlN/AlGaN super lattice structure (SLS) on the crystal quality of AlGaN epilayers grown by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). MT...
Kazuhide Sumiyoshi, Masashi Tsukihara, Ken Kataoka, Syuichi Kawamichi, Takashi Okimoto, Katsushi Nishino, Katsushi Nishino, Yoshiki Naoi, Yoshiki Naoi, Shiro Sakai, Shiro Sakai
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers   46 491-495   Feb 2007
The reduction of the dislocation density in a high-temperature (HT)-Al 0.17Ga0.83N epitaxial layer was achieved by a middle-temperature (MT)-intermediate layer technique, in which the HT and the MT were 1050 and 950̊C, respectively. For one set of...
Kazuhide Sumiyoshi, Masashi Tsukihara, Ken Kataoka, Shuichi Kawamichi, Tadashi Okimoto, Katsushi Nishino, Yoshiki Naoi, Shiro Sakai
Journal of Crystal Growth   298 300-304   Jan 2007
A technique to grow low-dislocation-density AlGaN films is presented in this paper. The Al0.17Ga0.83N films using middle temperature (MT)-intermediate layer technique grown by metalorganic chemical vapor deposition on c-plane patterned sapphire we...
F. W. Yan, Y. Naoi, M. Tsukihara, S. Kawamichi, T. Yadani, K. Sumiyoshi, S. Sakai
Physica B: Condensed Matter   376-377 595-597   Apr 2006
Alloying formation of In(Ga)NAs epilayers has been realized on a GaAs (1 0 0) substrate during the InAs-InN metalorganic chemical vapor deposition (MOCVD) growth process, and the underlying mechanism is attributed to atomic interdiffusion effect. ...
Takashi Okimoto, Masashi Tsukihara, Kazuhide Sumiyoshi, Ken Kataoka, Katsushi Nishino, Yoshiki Naoi, Shiro Sakai
Japanese Journal of Applied Physics, Part 2: Letters   45    Mar 2006
AlxGa1-xN (x ≤ 0.1) epilayers grown on (0001) sapphire substrates by low-pressure metalorganic chemical vapor deposition with low-temperature (LT)-GaNP buffer have been characterized using X-ray diffraction (XRD) and scanning electron microscopy (...
R. J. Choi, S. Kubo, M. Tsukihara, K. Inoue, Y. Naoi, K. Nishino, S. Sakai
Physica Status Solidi C: Conferences   2 2149-2152   Nov 2005
We investigated the structural and optical properties of AlInGaN/AlGaN quantum wells (QWs) and the quaternary AlInGaN epilayers as a function of V/III flux ratio (flow rate of NH3). From the photoluminescence and cathodoluminescence (CL) measureme...
Y. Naoi, H. Sato, H. Yamamoto, K. Ono, A. Nakamura, MKimura, S. Nouda, S. Sakai
Proceedings of SPIE - The International Society for Optical Engineering   5722 417-424   Aug 2005
370nm AlGaInN-based light emitting diodes (LEDs) with SiN in the active layer, fabricated on sapphire substrates by one-time metal organic chemical vapor deposition (MOCVD) have been investigated. Atomic force microscopy and cathodoluminesence res...
Fawang Yan, Yoshiki Naoi, Masashi Tsukihara, Takayuki Yadani, Shiro Sakai
Journal of Crystal Growth   282 29-35   Aug 2005
A unique growth manner for the formation of In(Ga)NAs film on GaAs (1 0 0) substrate is presented in this paper. The In(Ga)NAs compound alloy is significantly realized when a thin InN film is attempted to be overgrown on an InAs prelayers by metal...
Fawang Yan, Masashi Tsukihara, Akihiro Nakamura, Takayuki Yadani, Tetsuya Fukumoto, Yoshiki Naoi, Shiro Sakai
Japanese Journal of Applied Physics, Part 2: Letters   43    Aug 2004
A buffer technique that initially alternates supply of ammonia (IASA) is employed for AlN film growth on sapphire substrate by metalorganic chemical vapor deposition (MOCVD). Atomic force microscopy (AFM) study reveals that step-flow-like growth m...
H. D. Li, H. D. Li, M. Tsukihara, Y. Naoi, Y. B. Lee, S. Sakai
Applied Physics Letters   84 1886-1888   Mar 2004
A defect with V-shaped features formed in GaN-rich GaNP layers was investigated using TEM and AFM. The emission enhancement is attributed to lowering of the dislocation density and enlarging the escape cone of photons by the rough surface. Photolu...
Jin Ping Ao, Naotaka Kubota, Daigo Kikuta, Yoshiki Naoi, Yasuo Ohno
Physica Status Solidi C: Conferences   2376-2379   Dec 2003
The thermal stability of copper (Cu)-gate AlGaN/GaN high electron mobility transistors (HEMTs) was investigated by annealing the devices at 300 °C and 500 °C for 1 h, and at 700 °C for 30 min, respectively. The current-voltage performance of the d...
Masashi Tsukihara, Yoshiki Naoi, Hong Dong Li, Tomoya Sugahara, Shiro Sakai
Physica Status Solidi C: Conferences   2757-2760   Dec 2003
We developed a new buffer layer to grow GaN epilayers with a low dislcoation density by metalorganic chemical vapor deposition (MOCVD). The buffer layer consists of a 20 nm GaNP layer deposited at low temperature (500 °C) on sapphire substrate usi...
Yoshiki Naoi, Toshihiko Tada, Hongdong Li, Nan Jiang, Shiro Sakai
Physica Status Solidi C: Conferences   2077-2081   Dec 2003
GaN epilayers grown with introducing a high-temperature SiN interlayer by metalorganic chemical vapour deposition (MOCVD) were investigated by means of XRD, AFM, and TEM. SiN4 was used as Si source for SiN growth. It was found that by inserting th...
Young Bae Lee, Ryohei Takaki, Hisao Sato, Yoshiki Naoi, Shiro Sakai
Physica Status Solidi (A) Applied Research   200 87-90   Nov 2003
We have studied a new method of increasing the extraction efficiency of a GaN-based light-emitting diode (LED) using a plasma surface treatment. In this method, prior to the evaporation of a semitransparent p-metal, the surface of a p-GaN located ...
Jin Ping Ao, Daigo Kikuta, Naotaka Kubota, Yoshiki Naoi, Yasuo Ohno
IEICE Transactions on Electronics   E86-C 2051-2057   Oct 2003
High-temperature stability of copper (Cu) gate AlGaN/GaN high electron mobility transistors (HEMTs) was investigated. Samples were annealed at various temperatures to monitor the changes on device performances. Current-voltage performance such as ...
Jin Ping Ao, Daigo Kikuta, Naotaka Kubota, Yoshiki Naoi, Yasuo Ohno
IEEE Electron Device Letters   24 500-503   Aug 2003
Copper (Cu) gate AlGaN/GaN high electron mobility transistors (HEMTs) with low gate leakage current were demonstrated. For comparison, nickel/gold (Ni/Au) gate devices were also fabricated with the same process conditions except the gate metals. C...
Hiroyuki Naoi, Hiroyuki Naoi, Denis M. Shaw, Denis M. Shaw, Yoshiki Naoi, Shiro Sakai, George J. Collins
Journal of Crystal Growth   250 290-297   Apr 2003
InAs was grown by low-pressure metalorganic chemical vapor deposition on vicinal GaAs(1 0 0) substrates misoriented by 2° toward [0 0 1]. We observed InAs crystal growth, at substrate temperatures down to 300°C, employing in situ plasma-generated ...
M. Tsukihara, Y. Naoi, S. Sakai, H. D. Li
Applied Physics Letters   82 919-921   Feb 2003
The development of a buffer layer to grow GaN epilayers by metalorganic chemical vapor deposition was reported. The layer consisted of a thin GaN-rich GaNP layer deposited on sapphire substrate at low temperature (500° C). It was found that the qu...
Hongdong Li, Masashi Tsukihara, Yoshiki Naoi, Shiro Sakai
Japanese Journal of Applied Physics, Part 2: Letters   41    Nov 2002
Dislocation defects in a GaN epilayer grown on a low-temperature GaN-rich GaNP (LT-GaNP) buffer on sapphire substrate by low-pressure metalorganic chemical vapor deposition (LP-MOCVD) were investigated by means of transmission electron microscopy ...
Young Bae Lee, Tao Wang, Yu Huai Liu, Jin Ping Ao, Hong Dong Li, Hisao Sato, Katsushi Nishino, Yoshiki Naoi, Shiro Sakai
Japanese Journal of Applied Physics, Part 2: Letters   41    Oct 2002
We report a new method of increasing the output power of an ultraviolet light-emitting diode (UV-LED) based on an AlGaN/ GaN Single quantum well (SQW). In this method, a thin Ga droplet layer is intentionally grown before the growth of an AlGaN/Ga...
Jie Bai, Tao Wang, Yuhuai Liu, Yoshiki Naoi, Hongdong Li, Shiro Sakai, Shiro Sakai
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers   41 5909-5911   Oct 2002
Mg-doped AlGaN/GaN superlattice structures (SLS) grown by metalorganic chemical vapor deposition (MOCVD) are investigated by transmission electron microscopy (TEM) and photoluminescence (PL) measurements. TEM shows the good quality of moderately d...
Young Bae Lee, Tao Wang, Yu Huai Liu, Jin Ping Ao, Yuji Izumi, Yves Lacroix, Hong Dong Li, Jie Bai, Yoshiki Naoi, Shiro Sakai
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers   41 4450-4453   Jul 2002
A 348 nm ultraviolet-light-emitting diode (UV-LED) based on an AlGaN/GaN single quantum well (SQW) with a high optical power is reported. In this structure, a thin SiN buffer is introduced before the growth of a conventional low-temperature GaN bu...
H. Yamamoto, Y. Naoi, Y. Fujii, Y. Shintani
International Journal of Modern Physics B   16 841-844   Mar 2002
We have grown laterally overgrown diamond films on stripe patterned silicon substrates by microwave plasma chemical vapor deposition. Titanium was used as the mask material and stripe patterns were fabricated using conventional photolithographic m...
Hirofumi Yamamoto, Yoshiki Naoi, Yoshihiro Shintani
Journal of Crystal Growth   236 176-180   Mar 2002
We grew diamond films on grooved silicon substrates, without conventional scratching method to enhance the diamond nucleation. The grooved silicon substrates were prepared by anisotropic etching technique using KOH solution. The films were grown b...
Y. Naoi, Y. Kawakami, T. Nakanishi, Y. Lacroix, Y. Shintani, S. Sakai
Materials Science in Semiconductor Processing   4 555-558   Dec 2001
We investigated GaN films etched by using reactive ion etching (RIE) technique to fabricate the GaN-based devices. The samples were grown on sapphire substrate by metal organic chemical vapor deposition (MOCVD), and Ti/Al contacts were formed on n...
A. P. Young, L. J. Brillson, Y. Naoi, Y. Naoi, C. W. Tu
Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures   19 2063-2066   Nov 2001
A new technique for preserving the LEED (1×1) ordered surface of GaN by capping the film with a thin layer of metallic In is presented. The relatively low desorption temperature presents a benign method for transporting and processing GaN based he...
H. Naoi, D. M. Shaw, Y. Naoi, G. J. Collins, S. Sakai
Journal of Crystal Growth   222 511-517   Jan 2001
InNAs has been grown by low-pressure metalorganic chemical vapor deposition on vicinal GaAs(1 0 0) substrates misoriented by 2° towards [0 0 1]. In situ plasma-generated arsine radicals were employed for the first time to achieve high source flux ...
Alexander P. Young, Leonard J. Brillson, Yoshiki Naoi, Charles W. Tu
MRS Internet Journal of Nitride Semiconductor Research   5    Dec 2000
We have established a correlation between localized states responsible for mid-gap optical emission and film mobility of GaN grown under different nitrogen conditions. By imposing a deflector voltage at the tip of the plasma source, we varied the ...
S. Sakai, S. Sakai, T. Wang, Y. Morishima, Y. Naoi
Journal of Crystal Growth   221 334-337   Dec 2000
A method to drastically reduce dislocation density in a GaN film grown on sapphire substrate is newly developed. In this method, a very thin SixN1-x was deposited on the sapphire substrate at low temperature before growing conventional low-tempera...
Nan Jiang, Susumu Kujime, Hirofumi Yamamoto, Takeshi Inaoka, Yoshiki Naoi, Yoshihiro Shintani, Hiroshi Makita, Akimitsu Hatta, Akio Hiraki
Japanese Journal of Applied Physics, Part 2: Letters   39    Jun 2000
The initial stages of (111)-oriented diamonds grown on Pt substrates have been studied by both scanning electron microscopy (SEM) and transmission electron microscopy (TEM). TEM images clearly reveal that scratching pretreatment strongly damages t...
L. J. Brillson, L. J. Brillson, L. J. Brillson, A. P. Young, T. M. Levin, G. H. Jessen, J. Schäfer, Y. Yang, S. H. Xu, H. Cruguel, G. J. Lapeyre, F. A. Ponce, Y. Naoi, C. Tu, J. D. McKenzie, C. R. Abernathy
Materials Science and Engineering B: Solid-State Materials for Advanced Technology   75 218-223   Jun 2000
We have used low energy electron-excited nanoluminescence (LEEN) spectroscopy to probe the localized electronic states at GaN free surfaces, metal-GaN contacts, and GaN/InGaN quantum well interfaces. These depth-resolved measurements reveal the pr...
Alexander P. Young, Leonard J. Brillson, Yoshiki Naoi, Charles W. Tu
Materials Research Society Symposium - Proceedings   595    Jan 2000
We have established a correlation between localized states responsible for mid-gap optical emission and film mobility of GaN grown under different nitrogen conditions. By imposing a deflector voltage at the tip of the plasma source, we varied the ...
L. J. Brillson, T. M. Levin, G. H. Jessen, A. P. Young, C. Tu, Y. Naoi, F. A. Ponce, Y. Yang, G. J. Lapeyre, J. D. MacKenzie, C. R. Abernathy
Physica B: Condensed Matter   273-274 70-74   Dec 1999
We have used low-energy electron-excited nanoscale-luminescence (LEEN) spectroscopy combined with ultrahigh vacuum (UHV) surface science techniques to probe deep level defect states at GaN free surfaces, metal-GaN contacts and GaN/InGaN quantum we...
J. Wang, M. Nozaki, Y. Ishikawa, M. S. Hao, Y. Morishima, T. Wang, Y. Naoi, S. Sakai
Journal of Crystal Growth   197 48-53   Dec 1999
Nanoscale InGaN quantum wires and quantum dots (QDs) have been realized on the top of micron size of GaN dots and wires by lateral overgrowth with Si mask using metal-organic chemical vapor deposition (MOCVD). Patterning of the mask was carried ou...
Doo Hyeb Youn, Mohamed Lachab, Maosheng Hao, Tomoya Sugahara, Hironori Takenaka, Yoshiki Naoi, Shiro Sakai, Shiro Sakai
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers   38 631-634   Dec 1999
An investigation on the p-type activation in Mg-dopcd GaN epilayers has been carried out in relation to the defect structure. The samples were grown by the melalorganic chemical vapor deposition method. Sapphire with (0001) orientation (C-face) wa...
S. Mahanty, M. Hao, T. Sugahara, R. S Q Fareed, Y. Morishima, Y. Naoi, T. Wang, S. Sakai, S. Sakai
Materials Letters   41 67-71   Oct 1999
InGaN/GaN multiquantum well (MQW) structures have been grown on (0001) sapphire substrate by metalorganic chemical vapor deposition. From cross-sectional transmission electron microscopy (TEM), a number of V-shaped defects has been observed on the...
T. Tsuruoka, M. Kawasaki, S. Ushioda, R. Franchy, Y. Naoi, T. Sugahara, S. Sakai, Y. Shintani
Surface Science   427-428 257-261   Jun 1999
The oxidation of the GaN (0001) surface in the temperature range between 300 and 700 K has been studied by means of high-resolution electron energy loss spectroscopy (HREELS) and low-energy electron diffraction (LEED). The HREEL spectrum of the cl...
M. Hao, S. Mahanty, T. Sugahara, Y. Morishima, H. Takenaka, J. Wang, S. Tottori, K. Nishino, Y. Naoi, S. Sakai
Journal of Applied Physics   85 6497-6501   May 1999
The dislocation distribution and emission characteristics of lateral overgrowth GaN films grown by the sublimation technique and metallorganic chemical vapor deposition were determined by transmission electron microscopy and cathodoluminescence sp...
J. Wang, M. Nozaki, M. Lachab, R. S. Qhalid Fareed, Y. Ishikawa, T. Wang, Y. Naoi, S. Sakai, S. Sakai
Journal of Crystal Growth   200 85-89   Apr 1999
Nano-scale InGaN/GaN multi-structures have been grown on amorphous Si substrates using metal-organic chemical vapor deposition (MOCVD). The density, lateral size and height of the grown nano-scale InGaN/GaN multi-structures were estimated to be 10...
Maosheng Hao, Tomoya Sugahara, Satoru Tottori, Masaaki Nozaki, Satoshi Kurai, Katsushi Nishino, Yoshiki Naoi, Shiro Sakai
Proceedings of SPIE - The International Society for Optical Engineering   3419 138-145   Dec 1998
A GaN film grown on sapphire substrate by metalorganic chemical vapor deposition have been investigated by the plan-view TEM and CL. Direct evidence of dislocation being a non-radiative recombination center, have been provided. A bulk GaN grown by...
S. Sakai, H. Sato, T. Sugahara, Y. Naoi, S. Kurai, K. Yamashita, S. Tottori, M. Hao, K. Wada, K. Nishino
Materials Science Forum   264-268 1107-1110   Dec 1998
The growth of a bulk GaN by the sublimation method and the homoepitaxy were described. The effects of the surface pre-treatment of the bulk GaN substrate on the homoepitaxial layer properties have been investigated. A strong CL intensity of GaN ep...
Hiroki Uemura, Hirofumi Yamamoto, Takeshi Inaoka, Hiroshi Makita, Yoshiki Naoi, Yoshihiro Shintani
New Diamond and Frontier Carbon Technology   8 339-346   Dec 1998
In the case of platinum substrates, azimuthal orientation and coalescence of diamond films depend on the size of the nucleus and the nucleation density. It was found that the size and density of diamond particles are significantly influenced by th...
Tomoya Sugahara, Maosheng Hao, Tao Wang, Daisuke Nakagawa, Yoshiki Naoi, Katsusi Nishino, Shiro Sakai
Japanese Journal of Applied Physics, Part 2: Letters   37    Oct 1998
The role of dislocation for luminescence in InGaN grown on sapphire substrate by metal organic chemical vapor deposition (MOCVD) method was investigated by cathodoluminescence (CL) and atomic force microscopy (AFM). The CL emission area and dark s...
Doo Hyeb Youn, Maosheng Hao, Yoshiki Naoi, Sourindra Mahanty, Shiro Sakai, Shiro Sakai
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers   37 4667-4671   Sep 1998
The Ni/AuZn and Cr/AuZn contacts for achieving a low resistance ohmic contact to moderately doped p-GaN(4.4 × 1017/cm3) have been reported. In order to determine the reasons for the difference in ohmic characteristics of both metals, we have compa...
Shiro Sakai, Tin S. Cheng, Thomas C. Foxon, Tomoya Sugahara, Yoshiki Naoi, Hiroyuki Naoi
Journal of Crystal Growth   189-190 471-475   Jun 1998
An InNAs ternary alloy which was predicted to have a very narrow or even a negative band-gap energy was grown on GaAs(1 0 0) substrate by molecular-beam epitaxy (MBE). A ternary alloy with a nitrogen content of about 38%, which was almost lattice-...
T. Tsuruoka, N. Takahashi, R. Franchy, S. Ushioda, Y. Naoi, H. Sato, S. Sakai, Y. Shintani
Journal of Crystal Growth   189-190 677-681   Jun 1998
The properties of a GaN film have been investigated by means of high-resolution electron-energy-loss spectroscopy (HREELS), low-energy electron diffraction (LEED), and Raman spectroscopy. The sample was grown on sapphire(0 0 0 1) substrate by meta...
Y. Naoi, K. Kobatake, S. Kurai, K. Nishino, H. Sato, M. Nozaki, S. Sakai, Y. Shintani
Journal of Crystal Growth   189-190 163-166   Jun 1998
We have characterized a bulk GaN grown by sublimation technique by means of the high resolution X-ray diffraction measurements, the secondary ion mass spectrometry measurements, the Raman spectroscopy measurements and the resistivity measurements....
Hisao Sato, Tomoya Sugahara, Yoshiki Naoi, Shiro Sakai
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers   37 2013-2015   Apr 1998
The compositional inhomogeneity of the InGaN layers in GaN/InGaN/GaN double-hetero (DH) and InGaN/GaN single-hetero (SH) structures grown by metalorganic chemical vapor deposition (MOCVD) on sapphire (0001) and bulk GaN was investigated by means o...
Doo Hyeb Youn, Maosheng Hao, Hisao Sato, Tomoya Sugahara, Yoshiki Naoi, Shiro Sakai
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers   37 1768-1771   Apr 1998
Investigations of the new metal scheme for ohmic contact to p-GaN have been carried out. The specific contact resistance was measured to be ρc=3.6×10-3 Ω cm2 which is the lowest value ever reported for moderately doped p-GaN (4.4×1017/cm3). All me...
Maosheng Hao, Tomoya Sugahara, Hisao Sato, Yoshiyuki Morishima, Yoshiki Naoi, Linda T. Romano, Shiro Sakai
Japanese Journal of Applied Physics, Part 2: Letters   37    Mar 1998
The threading dislocations in GaN films grown on Al2O3 substrates were studied by plan view transmission electron microscopy (TEM). A pure edge dislocation and a mixed dislocation with different kinds of screw components, could be distinguished by...
Hisao Sato, Tomoya Sugahara, Maosheng Hao, Yoshiki Naoi, Satoshi Kurai, Kenji Yamashita, Katsushi Nishino, Shiro Sakai
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers   37 626-631   Feb 1998
Homoepitaxial growth of GaN on bulk GaN prepared by the sublimation method was performed by metalorganic chemical vapor deposition (MOCVD). Two kinds of bulk substrates were used for homoepitaxial growth: (i) a polished bulk GaN C-face, selectivel...
Marek Osinski, Petr G. Eliseev, Piotr Perlin, Jinhyun Lee, Hisao Sato, Tomoya Sugahara, Yoshiki Naoi, Shiro Sakai
Conference on Lasers and Electro-Optics Europe - Technical Digest   276-277   Jan 1998
The temperature behavior and band tailing in InGaN/GaN heterostructures grown on sapphire by metal-organic chemical-vapor deposition are investigated. It is shown that thicker InGaN/GaN heterostructures exhibits behavior similar to that observed i...
Hiroki Uemura, Akira Mizoguchi, Takahiro Hanabusa, Kazutaka Takeda, Takeshi Inaoka, Hiroshi Makita, Yoshiki Naoi, Yoshihiro Shintani, Takeshi Tachibana
New Diamond and Frontier Carbon Technology   7 293-296   Dec 1997
Hisao Sato, Yoshiki Naoi, Shiro Sakai
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers   36 2018-2021   Apr 1997
The structural properties of the GaN layers and the GaN/InGaN/GaN double-hetero (DH) structures grown on sapphire (001) substrate using the metalorganic chemical vapor deposition (MOCVD) method were investigated using a high-resolution X-ray diffr...
Hiroyuki Naoi, Yoshiki Naoi, Shiro Sakai
Solid-State Electronics   41 319-321   Feb 1997
The ternary alloy InAsN has been grown by MOCVD for the first time. The growth was performed at 70 Torr using TMI, AsH 3 and NH 3 as source gases and GaAs(100) as substrate. The growth temperature and ...
Hisao Sato, Mihir Ranjan Sarkar, Mihir Ranjan Sarkar, Yoshiki Naoi, Shiro Sakai
Solid-State Electronics   41 205-207   Feb 1997
We have measured valence band discontinuity at GaP/GaN heterointerfaces by X-ray photoelectron spectroscopy. The experimental procedure is: (1) separate measurement of N1s and P2p core level energies with respect to the valence band top energy in ...
H. Sato, Y. Naoi, S. Sakai
Materials Research Society Symposium - Proceedings   449 441-446   Jan 1997
We have investigated lattice structures of GaN and InGaN/GaN single-heterostructures (SH) and double-heterostructures (DH) by the reciprocal space mapping using X-ray diffraction technique from (0002) plane. For a single GaN layers, the transition...
S. Sakai, S. Kurai, K. Nishino, K. Wada, H. Sato, Y. Naoi
Materials Research Society Symposium - Proceedings   449 15-22   Jan 1997
The growth of bulk GaN by sublimation method and a homoepitaxial growth by MOCVD are reported. A photo-pumped stimulated emission is obtained from a homoepitaxial layer. The source powder used as a source in the sublimation method is investigated ...
Tatsuya Okada, Satoshi Kurai, Yoshiki Naoi, Katsushi Nishino, Fukuji Inoko, Shiro Sakai
Japanese Journal of Applied Physics, Part 2: Letters   35    Oct 1996
A GaN film with nominal thickness of 0.6 μm was homoepitaxially deposited on a sublimation-grown GaN single-crystal substrate. An electron-transparent area of 10 μm × 10 μm prepared by focused Ga ion beam machining was examined by transmission ele...
Satoshi Kurai, Toshimitsu Abe, Yoshiki Naoi, Shiro Sakai
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers   35 1637-1640   Mar 1996
Thick GaN, 10-30 μm, was grown on sapphire substrate by a sublimation method for the first time. GaN was homoepitaxially grown on this thick layer by metalorganic chemical vapor deposition to obtain a high-quality layer. Stimulated emission from a...
Satoshi Kurai, Yoshiki Naoi, Toshimitsu Abe, Susumu Ohmi, Shiro Sakai
Japanese Journal of Applied Physics, Part 2: Letters   35    Jan 1996
We have observed stimulated emission at room temperature from a photopumped homoepitaxial GaN for the first time. A homoepitaxial layer was grown by atmospheric metalorganic chemical vapor deposition (MOCVD) on small hexagonal bulk GaN prepared by...
Yoshiki Naoi, Satoshi Kurai, Shiro Sakai, Tao Yang, Hoshihiro Shintani
Journal of Crystal Growth   145 321-325   Dec 1994
We have investigated, by photoluminescence measurement, the microscopic stress distribution near the dislocation in GaAs grown on Si substrate and in planar homoepitaxial GaAs which was grown by metalorganic chemical vapor deposition (MOCVD). It w...
Y. Naoi, K. Ito, Y. Uehara, S. Ushioda, Y. Murata
Surface Science   283 457-461   Mar 1993
The energy distribution of photoelectrons emitted from NEA-GaAs has been measured with a very high energy resolution (ΔE ≈ 5 meV). The sample consists of epitaxially grown p-type GaAs (hole concentration 1 × 1019 cm-3) with a (100) surface. After ...
Yuji Hirao, Yoshiki Naoi, Yoshinobu Nagano, Masuo Fukui
Journal of the Physical Society of Japan   60 4366-4373   Dec 1991
Emission characteristics of light radiated from a metal insulator-metal tunnel junction could be controlled by surface and interface roughnesses. To elucidate these situations, surface and interface roughnesses of the tunnel junction are evaluated...
Y. Naoi, M. Fukui
Physical Review B   42 5009-5012   Jan 1990
For an air/Ag-film(42.0 nm)/prism geometry, we have measured the intensity of the surface-plasmon polariton energy emitted through surface roughness into the air side and then simultaneously evaluated the surface-roughness parameters, i.e., the tr...
Yoshiki Naoi, Masuo Fukui
Journal of the Physical Society of Japan   58 4511-4516   Dec 1989
Light scattering is a powerf pair of roughness parameter, i.e. the amplitude of surface corrugation and the transverse correlation length. However, the paraul method to evaluate surface roughness parameters. From the information on radiation produ...

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Study on III-V nitrides semiconductor