研究者詳細 - 須田　淳

論文 - 須田　淳

分割表示 429 件中 261 - 280 件目／全件表示 >>

Tight-binding study of size and geometric effects on hole effective mass of silicon nanowires

Moriokaa N., Yoshioka H., Suda J., Kimoto T.

2010 Silicon Nanoelectronics Workshop, SNW 2010 2010年10月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：2010 Silicon Nanoelectronics Workshop, SNW 2010

The present tight-binding study of rectangular SiNWs along [001], [110], and [111] revealed that the hole m* of [001] and [110] NWs on the {001} basal face has strong dependence on the width. Because this nature may make the design of devices difficult, these NWs are considered to be unfavorable for p-channel devices. In contrast, rectangular [111] NWs on both (112̄) and (1̄10) basal faces are favorable for p-channel devices because they have the smallest hole m* and its value is very resistant to the variability of the width.

DOI： 10.1109/SNW.2010.5562567

Impacts of recombination at the surface and in the substrate on carrier lifetimes of n-type 4H-SiC epilayers

Kimoto Tsunenobu, Hiyoshi Toru, Hayashi Toshihiko, Suda Jun

JOURNAL OF APPLIED PHYSICS 108 巻 ( 8 ) 2010年10月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Applied Physics

After remarkable reduction in the Z1/2 center in n-type 4H-SiC epilayers, the measured carrier lifetimes can be severely affected by other recombination paths. Impacts of carrier recombination at the surface as well as in the substrate are investigated in detail by using numerical simulation based on a diffusion equation. The simulation reveals that a very thick (>100 μm) epilayer is required for accurate measurement of carrier lifetimes if the bulk lifetime in the epilayer is longer than several microsecond, due to the extremely short lifetimes in the substrate. The fast decay often observed at the initial stage of decay curves can be explained by fast recombination at the surface and in the substrate. In experiments, the carrier lifetime is improved from 0.69 to 9.5 μs by reducing the Z1/2 center via two-step thermal treatment (thermal oxidation and Ar annealing) for a 148-μm -thick n-type epilayer. This lifetime must be still, to large extent, affected by the recombination at the surface and in the substrate, and the real bulk lifetime may be much longer. The carrier recombination paths and their impacts on the decay curves are discussed. © 2010 American Institute of Physics.

DOI： 10.1063/1.3498818

Accurate measurement of quadratic nonlinear-optical coefficients of gallium nitride

Abe M., Sato H., Shoji I., Suda J., Yoshimura M., Kitaoka Y., Mori Y., Kondo T.

Journal of the Optical Society of America B: Optical Physics 27 巻 ( 10 ) 頁： 2026 - 2034 2010年10月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of the Optical Society of America B: Optical Physics

We have determined all the three independent components of quadratic nonlinear-optical coefficients of GaN by highly accurate Maker-fringe measurements on high-quality bulk samples combined with theoretical analysis taking account of the multiple-reflection effects in slightly misoriented optically anisotropic samples. Especially, the d33 coefficient is determined with sufficient accuracies for the first time, to our knowledge, by using (112̄0)-oriented samples. The obtained values of quadratic nonlinear-optical coefficients are d31 =2.5±0.1 pm/V, d 15=2.5±0.1 pm/V, and d33=-3.8±0.2 pm/V at the fundamental wavelength of 1.064 μm. © 2010 Optical Society of America.

DOI： 10.1364/JOSAB.27.002026

Accurate measurement of quadratic nonlinear-optical coefficients of gallium nitride

Abe Makoto, Sato Hiroaki, Shoji Ichiro, Suda Jun, Yoshimura Masashi, Kitaoka Yasuo, Mori Yusuke, Kondo Takashi

JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS 27 巻 ( 10 ) 頁： 2026 - 2034 2010年10月

Demonstration of Common-Emitter Operation in AlGaN/SiC Heterojunction Bipolar Transistors

Miyake Hiroki, Kimoto Tsunenobu, Suda Jun

IEEE ELECTRON DEVICE LETTERS 31 巻 ( 9 ) 頁： 942 - 944 2010年9月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE Electron Device Letters

We report here on the fabrication and characterization of new aluminum gallium nitride (AlGaN)/silicon carbide heterojunction bipolar transistors (HBTs). In the HBTs, AlN/GaN short-period superlattice (quasi-AlGaN) was employed as the widegap emitter. We have successfully demonstrated band-offset control and the first commonemitter-mode operation (β ∼ 2.7) in the HBTs. © 2010 IEEE.

DOI： 10.1109/LED.2010.2052012

Reduction of deep levels generated by ion implantation into n- and p-type 4H-SiC

Kawahara Koutarou, Suda Jun, Pensl Gerhard, Kimoto Tsunenobu

JOURNAL OF APPLIED PHYSICS 108 巻 ( 3 ) 2010年8月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Applied Physics

The authors have investigated effects of thermal oxidation on deep levels in the whole energy range of the band gap of 4H-SiC by deep level transient spectroscopy. The deep levels are generated by ion implantation. The dominant defects in n-type samples after ion implantation and high-temperature annealing at 1700 °C are IN3 (Z1/2: EC-0.63 eV) and IN9 (EH 6/7: EC-1.5 eV) in low-dose-implanted samples, and IN8 (EC-1.2 eV) in high-dose-implanted samples. These defects can remarkably be reduced by thermal oxidation at 1150 °C. In p-type samples, however, IP8 (HK4: EV +1.4 eV) survives and additional defects such as IP4 (HK0: EV +0.72 eV) appear after thermal oxidation in low-dose-implanted samples. In high-dose-implanted p-type samples, three dominant levels, IP5 (HK2: EV +0.85 eV), IP6 (EV +1.0 eV), and IP7 (HK3: EV +1.3 eV), are remarkably reduced by oxidation at 1150 °C. The dominant defect IP4 observed in p-type 4H-SiC after thermal oxidation can be reduced by subsequent annealing in Ar at 1400 °C. These phenomena are explained by a model that excess interstitials are generated at the oxidizing interface, which diffuse into the bulk region. © 2010 American Institute of Physics.

DOI： 10.1063/1.3456159

Sources of Epitaxial Growth-Induced Stacking Faults in 4H-SiC

Feng Gan, Suda Jun, Kimoto Tsunenobu

JOURNAL OF ELECTRONIC MATERIALS 39 巻 ( 8 ) 頁： 1166 - 1169 2010年8月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Electronic Materials

Successive reactive-ion etching and microphotoluminescence (PL) intensity mapping have been performed in order to investigate the sources of epitaxial growth-induced stacking faults (SFs) in thick 4H-SiC epilayers. Three kinds of SFs, i.e., 4SSFs, 3SSFs, and 2SSFs, have been identified in the samples. Two of these (3SSFs and 2SSFs) show similar nucleation behaviors, and their formation may be due to stress within the epitaxial layer. In contrast, 4SSFs nucleate at the epilayer-substrate interface and might be related to an unknown dislocation, which shows a rounded-shape etch pit in the substrate. © 2010 TMS.

DOI： 10.1007/s11664-010-1192-6

Deep levels induced by reactive ion etching in n- and p-type 4H-SiC

Kawahara Koutarou, Krieger Michael, Suda Jun, Kimoto Tsunenobu

JOURNAL OF APPLIED PHYSICS 108 巻 ( 2 ) 2010年7月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Applied Physics

In this study, the authors investigate deep levels, which are induced by reactive ion etching (RIE) of n-type/p-type 4H-SiC, by deep level transient spectroscopy (DLTS). The capacitance of a Schottky contact fabricated on as-etched p-type SiC is abnormally small due to compensation or deactivation of acceptors extending to a depth of ∼14 μm, which is nearly equal to the epilayer thickness. The value of the capacitance can recover to that of a Schottky contact on as-grown samples after annealing at 1000 °C. However, various kinds of defects, IN2 (EC-0.30 eV), EN (EC -1.6 eV), IP1 (EV +0.30 eV), IP2 (EV +0.39 eV), IP4 (HK0: EV +0.72 eV), IP5 (EV +0.85 eV), IP7 (EV +1.3 eV), and EP (EV +1.4 eV), remain at a high concentration (average of total defect concentration in the region ranging from 0.3 μm to 1.0 μm:∼5× 1014 cm-3) even after annealing at 1000 °C. The concentration of all these defects generated by RIE, except for the IP4 (HK0) center, remarkably decreases by thermal oxidation. In addition, the HK0 center can also be reduced significantly by a subsequent annealing at 1400 °C in Ar. © 2010 American Institute of Physics.

DOI： 10.1063/1.3460636

Electrical characterization and reliability of nitrided-gate insulators for N- and P-Type 4H-SiC MIS devices

Noborio M., Grieb M., Bauer A.J., Peters D., Friedrichs P., Suda J., Kimoto T.

Materials Science Forum 645-648 巻頁： 825 - 828 2010年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Materials Science Forum

In this paper, nitrided insulators such as N2O-grown oxides, deposited SiO2 annealed in N2O, and deposited SiN x/SiO2 annealed in N2O on thin-thermal oxides have been investigated for realization of high performance n- and p-type 4H-SiC MIS devices. The MIS capacitors were utilized to evaluate MIS interface characteristics and the insulator reliability. The channel mobility was determined by using the characteristics of planar MISFETs. Although the N 2O-grown oxides are superior to the dry O2-grown oxides, the deposited SiO2 and the deposited SiNx/SiO2 exhibited lower interface state density (n-MIS: below 7×1011 cm-2eV-1 at EC-0.2 eV, p-MIS: below 6×1011 cm-2eV-1 at EV+0.2 eV) and higher channel mobility (n-MIS: over 25 cm2/Vs, p-MIS: over 10 cm2/Vs). In terms of reliability, the deposited SiO2 annealed in N2O exhibits a high charge-to-breakdown over 50 C/cm 2 at room temperature and 15 C/cm2 at 200°C. The nitrided-gate insulators formed by deposition method have superior characteristics than the thermal oxides grown in N2O. © (2010) Trans Tech Publications, Switzerland.

DOI： 10.4028/www.scientific.net/MSF.645-648.825

Enhancement of initial layer-by-layer growth and reduction of threading dislocation density by optimized Ga pre-irradiation in molecular-beam epitaxy of 2H-AlN on 6H-SiC (0001)

Okumura Hironori, Kimoto Tsunenobu, Suda Jun

PHYSICA STATUS SOLIDI C: CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 7, NO 7-8 7 巻 ( 7-8 ) 頁： 2094 - 2096 2010年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Physica Status Solidi (C) Current Topics in Solid State Physics

300-nm-thick AlN layers without a nucleation layer were grown on 6H-SiC (0001) vicinal substrates with 3-bilayer-height steps by rf-plasma-assisted molecular-beam epitaxy. A Ga beam was supplied for 0 to 30 seconds just before growth of AlN. The Ga pre-irradiation for 7 seconds (~1.6 ML) was found to be effective for realization of the AlN layer-by-layer growth mode at an earlier stage of the growth and reduction of threading dislocation densities (TDD) in the AlN layers. The screw-type and edge-type TDDs were ∼106 cm-2 and 6×108 cm-2, respectively. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.

DOI： 10.1002/pssc.200983579

Enhancement of Carrier Lifetimes in n-Type 4H-SiC Epitaxial Layers by Improved Surface Passivation

Kimoto Tsunenobu, Nanen Yuichiro, Hayashi Toshihiko, Suda Jun

APPLIED PHYSICS EXPRESS 3 巻 ( 12 ) 2010年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Physics Express

Carrier lifetimes in n-type 4H-SiC epitaxial layers are limited by several factors such as deep levels, surface recombination, and recombination in the substrate. In this study, the carrier lifetime is significantly improved from 0.68 to 13.1 μs by eliminating deep levels and by improving surface passivation. Deep levels can be almost eliminated by two-step annealing as reported before, and the surface recombination can be reduced by passivating the surface with a deposited oxide annealed in nitric oxide at 1300 °C. Major recombination paths are discussed based on numerical simulation. © 2010 The Japan Society of Applied Physics.

DOI： 10.1143/APEX.3.121201

Influence of Effective Fixed Charges on Short-Channel Effects in SiC Metal-Oxide-Semiconductor Field-Effect Transistors

Noborio Masato, Suda Jun, Kimoto Tsunenobu

JAPANESE JOURNAL OF APPLIED PHYSICS 49 巻 ( 2 ) 2010年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

Influence of effective fixed charges, which are located near the metal-oxide-semiconductor (MOS) interface, on short-channel effects in 4H-SiC MOS field-effect transistors (FETs) has been investigated. The relationship between the threshold voltage and the channel length was theoretically calculated by using an original charge-share model, which takes the effective fixed charges into account. As a result, it was revealed that the effective fixed charges, which are attributed to electron trapping at the interface states, affect the relationship. The threshold voltage is decreased by reducing the channel length in the relatively-long channel region when the effective fixed charges exist. The theoretical relationship between the threshold voltage and the channel length calculated by using the proposed model agrees very well with the experimental results. © 2010 The Japan Society of Applied Physics.

DOI： 10.1143/JJAP.49.024204

Nonpolar 4H-Polytype AlN/AlGaN Multiple Quantum Well Structure Grown on 4H-SiCd(1(1)over-bar00)

Horita Masahiro, Kimoto Tsunenobu, Suda Jun

APPLIED PHYSICS EXPRESS 3 巻 ( 5 ) 2010年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Physics Express

Nonpolar 4H-polytype AlN/AlGaN multiple quantum well (MQW) structures were grown on 4H-SiC(11̄00) substrates by molecular-beam epitaxy. Layer-by-layer growth of MQW layers is observed and abrupt AlN/AlGaN interfaces have been achieved. Generation of additional extended defects is not observed at the AlN/AlGaN interfaces and the crystal structure of 4H-polytype is preserved throughout the entire MQW structure. In cathodoluminescence spectra, a band-edge emission peak is observed at 5.41 eV (229 nm). The band edge peak position is not blue-shifted when the irradiation beam current is increased. © 2010 The Japan Society of Applied Physics.

DOI： 10.1143/APEX.3.051001

Nondestructive Visualization of Individual Dislocations in 4H-SiC Epilayers by Micro Photoluminescence Mapping

Feng Gan, Suda Jun, Kimoto Tsunenobu

JAPANESE JOURNAL OF APPLIED PHYSICS 49 巻 ( 9 ) 2010年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Japanese Journal of Applied Physics

Dislocations in 4H-SiC epilayers were imaged nondestructively by means of micro photoluminescence (μ-PL) mapping at room temperature. The one-to-one correspondence between the individual dislocations and the μ-PL mapping contrast has been consistently obtained. By analyzing the reduction of the intensity in the μ-PL mapping image performed at 390nm (near band-edge emission), we were able to distinguish threading screw dislocations and threading edge dislocations. Furthermore, it was found that a basal plane dislocation dissociates into a single Shockley stacking fault during the measurement. © 2010 The Japan Society of Applied Physics.

DOI： 10.1143/JJAP.49.090201

Non-destructive detection and visualization of extended defects in 4H-SiC epilayers

Feng Gan, Suda Jun, Kimoto Tsunenobu

B - SILICON CARBIDE 2010-MATERIALS, PROCESSING AND DEVICES 1246 巻頁： 37 - 42 2010年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Materials Research Society Symposium Proceedings

The extended defects, such as dislocations and in-grown stacking faults (IGSFs), in 4H-SiC epilayers have been detected and visualized by a non-destructive method, the micro photoluminescence (μ-PL) intensity mapping method, at room temperature. The one-to-one correspondence between the extended defects and the μ-PL mapping contrast has been successfully obtained. A threading dislocation corresponds to a dark circle with the reduced intensity in the μ-PL mapping image performed at 390 nm, while a basal plane dislocation dissociates into a single Shockley SF during the measurements. Three kinds of IGSFs have been identified in the samples. Each kind of IGSF shows the distinct PL emission located at 460 nm, 480 nm, and 500 nm, respectively. The shapes and distributions of IGSFs have also been profiled by μ-PL intensity mapping. © 2010 Materials Research Society.

DOI： 10.1557/PROC-1246-B03-02

Nearly Ideal Current-Voltage Characteristics of Schottky Barrier Diodes Formed on Hydride-Vapor-Phase-Epitaxy-Grown GaN Free-Standing Substrates

Suda Jun, Yamaji Kazuki, Hayashi Yuichirou, Kimoto Tsunenobu, Shimoyama Kenji, Namita Hideo, Nagao Satoru

APPLIED PHYSICS EXPRESS 3 巻 ( 10 ) 2010年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Physics Express

The current-voltage characteristics of Schottky barrier diodes formed on GaN(0001) free-standing substrates with net donor concentrations of 7:6 × 1015-1:4 × 1017 cm-3 are discussed. The substrates were grown by hydride vapor phase epitaxy. Ni Schottky contacts were directly formed on chemical-mechanical-polished Ga-polar faces of the substrates. Nearly ideal characteristics for both directions were obtained. The ideality factors for forward characteristics are 1.02 -1.05, very close to unity. The reverse characteristics agree well with calculations based on thermionicfield emission theory without any fitting parameter. © 2010 The Japan Society of Applied Physics.

DOI： 10.1143/APEX.3.101003

Lifetime-killing defects in 4H-SiC epilayers and lifetime control by low-energy electron irradiation

Kimoto Tsunenobu, Danno Katsunori, Suda Jun

SILICON CARBIDE, VOL 1: GROWTH, DEFECTS, AND NOVEL APPLICATIONS 頁： 267 - 286 2010年

Temperature and injection level dependencies of carrier lifetimes in p-type and n-type 4H-SiC epilayers

Hayashi T., Asano K., Suda J., Kimoto T.

Materials Science Forum 645-648 巻頁： 199 - 202 2010年

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Materials Science Forum

Temperature and injection level dependencies of carrier lifetimes in p-type and n-type 4H-SiC epilayers have been investigated. The carrier lifetimes have been measured by differential microwave photoconductance decay measurements at various injection levels and temperatures. In both p-type and n-type epilayers, the carrier lifetimes gradually increased with increasing the injection level except for the very high injection condition. And the carrier lifetimes exhibited continuous increase with elevating the temperature for both epilayers. The carrier lifetime reached 3.3 μs in p-type and 4.2 μs in n-type epilayers at 250°C and an injection level of 1.8×1016 cm-3. © (2010) Trans Tech Publications.

DOI： 10.4028/www.scientific.net/MSF.645-648.199

Characterization of major in-grown stacking faults in 4H-SiC epilayers

Feng Gan, Suda Jun, Kimoto Tsunenobu

PHYSICA B-CONDENSED MATTER 404 巻 ( 23-24 ) 頁： 4745 - 4748 2009年12月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Physica B: Condensed Matter

The optical properties of major in-grown stacking faults (IGSFs) in 4H-SiC epilayers have been characterized by micro-photoluminescence (micro-PL) spectroscopy and its intensity mapping. Strong PL emissions from the IGSFs are observed even at room temperature. Three kinds of IGSFs have been identified in the samples based on the micro-PL spectra. Each kind of IGSF shows the distinct PL emission peak located at 460, 480, and 500 nm, respectively. The micro-PL intensity mapping at the emission band of each IGSF has been performed to spatially profile the IGSF. The shapes, distributions, and densities of IGSFs in the epilayers are then presented. The microstructure of each IGSF has been revealed by high-resolution transmission electron microscopy observations. The stacking sequences of three IGSFs are determined as (4,4), (3,5), and (6,0) in the Zhdanov's notation, respectively, which apparently differ from the perfect 4H-SiC, (2,2). Three identified IGSFs are then classified as quadruple Shockley SFs, triple Shockley SFs, and double Shockley SFs, respectively, based on the shear formation model. © 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physb.2009.08.189

Demonstration of SiC heterojunction bipolar transistors with AlN/GaN short-period superlattice widegap emitter

Miyake H., Kimoto T., Suda J.

Device Research Conference - Conference Digest, DRC 頁： 281 - 282 2009年12月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：Device Research Conference - Conference Digest, DRC

SiC bipolar-junction transistors (BJTs) are attractive candidates for high-power switching devices due to their high breakdown voltage and low on-resistance. However, SiC BJT has so far suffered from the limited current gain. An alternative device structure would be heterojunction bipolar transistors (HBTs). Because it is impossible to grow SixC 1-x solid solutions with x near 0.5, HBTs cannot be fabricated within group-IV semiconductors. Heteroepitaxial growth of wider bandgap group-III nitride (Al)GaN on SiC is one possible way to realize bandgap engineering in SiC devices. The fabrication of (Al)GaN/SiC HBTs was first reported by Pankove et al. [1] followed by several groups [2]. But any HBTs did not show common-emitter mode operation due to the large leakage at the emitterjunction. © 2009 IEEE.

DOI： 10.1109/DRC.2009.5354933

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