研究者詳細 - 須田　淳

論文 - 須田　淳

分割表示 429 件中 101 - 120 件目／全件表示 >>

Determination of Surface Recombination Velocity From Current-Voltage Characteristics in SiC p-n Diodes

Asada Satoshi, Suda Jun, Kimoto Tsunenobu

IEEE TRANSACTIONS ON ELECTRON DEVICES 65 巻 ( 11 ) 頁： 4786 - 4791 2018年11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 Transactions on Electron Devices

Surface recombination velocity on mesa sidewalls of SiC p-n diodes with various surface passivation conditions was evaluated from the device-size-dependent preexponential factor of recombination current (J0rec). The diodes passivated by SiO2 with postoxidation nitridation were dipped into HF to eliminate a shunt current, which is evoked by the nitrided SiO2 layer and disturbs the analysis of the recombination current. For accurate determination of the surface recombination velocity, an effective recombination zone width was precisely derived taking account of the distribution of carrier density in the depletion layer. The surface recombination velocity of the diodes without any passivation and with the postoxidation nitridation (NO annealing at 1250 °C for 70 min) was determined as 1.2 × 107 and 6.0 × 105 cm/s, respectively, which indicates that the postoxidation nitridation can reduce the surface recombination by a factor of about 20. We confirmed that TCAD simulation could reproduce the current-voltage characteristics by utilizing the extracted parameters. In addition, an evaluation method was proposed to determine the surface recombination velocity from the high-current region, where diffusion current is dominant.

DOI： 10.1109/TED.2018.2867545

Carrier lifetime and breakdown phenomena in SiC power device material

Kimoto T., Niwa H., Okuda T., Saito E., Zhao Y., Asada S., Suda J.

JOURNAL OF PHYSICS D-APPLIED PHYSICS 51 巻 ( 36 ) 2018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：Journal of Physics D: Applied Physics

Recent progress and current understanding of carrier lifetimes and avalanche phenomena in silicon carbide (SiC) are reviewed. The acceptor level of carbon vacancy (V C), called the Z 1/2 center, has been identified to be the primary carrier lifetime killer in SiC. The V C defects can be eliminated by the introduction of excess carbon atoms followed by carbon diffusion in the bulk region. The true bulk lifetime after V C elimination was estimated to be approximately 110 μs. The doping dependence of carrier lifetimes in n- and p-type SiC is also presented. The impact ionization coefficients of electrons and holes were extracted in the temperature range of 298 to 423 K. The intrinsic critical electric field strength of SiC0 0 0 1 was determined to be 2.0, 2.5, and 3.3 MV cm-1 for doping densities of 1 × 1015, 1 × 1016, and 1 × 1017 cm-3, respectively, at room temperature; it slightly increased at elevated temperature. The obtained set of impact ionization coefficients has enabled us to accurately predict the breakdown voltage of SiC devices, including its temperature dependence. Due to the unusually low impact ionization coefficient of electrons, the breakdown voltage of a SiC p+n junction is about 6%-9% higher than that of an n+p junction with a given doping density.

DOI： 10.1088/1361-6463/aad26a

Phonon-assisted optical absorption due to Franz-Keldysh effect in 4H-SiC p-n junction diode under high reverse bias voltage

Maeda, T; Chi, XL; Horita, M; Suda, J; Kimoto, T

APPLIED PHYSICS EXPRESS 11 巻 ( 9 ) 2018年9月

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

Photocurrent in a 4H-SiC p-n junction diode under illumination with sub-bandgap light was investigated. Under a high reverse bias condition, the photocurrent significantly increased with an increase in the reverse bias voltage. We calculated the photocurrent taking into consideration the phonon-assisted optical absorption due to the Franz-Keldysh effect. The calculated photocurrent showed good agreement with the experimental results. The photocurrent also increased at elevated temperatures, which could be quantitatively explained by the redshift of the 4H-SiC absorption edge (the shrinkage of the bandgap) and the increase in the phonon occupation number with rising temperature.

DOI： 10.7567/APEX.11.091302

Analytical formula for temperature dependence of resistivity in p-type 4H-SiC with wide-range doping concentrations

Asada Satoshi, Suda Jun, Kimoto Tsunenobu

JAPANESE JOURNAL OF APPLIED PHYSICS 57 巻 ( 8 ) 2018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：Japanese Journal of Applied Physics

Temperature dependence of resistivity from 250 to 900K in p-type 4H-SiC with various doping concentrations (5.8 × 1014-7.1 × 1018cm-3) was presented. The resistivity was obtained by the van der Pauw method in samples, whose doping concentrations were precisely determined in our previous work. From the experimental results, coefficients for a fitting formula with polynomial approximation were derived. We confirmed that the fitting formula can accurately estimate the resistivity of p-type SiC with wide-range doping concentrations.

DOI： 10.7567/JJAP.57.088002

Accurate method for estimating hole trap concentration in n-type GaN via minority carrier transient spectroscopy

Kanegae, K; Horita, M; Kimoto, T; Suda, J

APPLIED PHYSICS EXPRESS 11 巻 ( 7 ) 2018年7月

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

We propose an analysis method for the accurate estimation of the hole trap (H1, EV + 0.85 eV) concentration in n-type GaN via minority carrier transient spectroscopy (MCTS). The proposed method considers both the hole occupation during a filling (current injection) period and the quick carrier recombination via the hole traps near the depletion layer edge immediately after a reverse bias is applied. The reverse bias voltage dependence of the MCTS spectrum indicates that an accurate trap concentration, as well as the hole diffusion length and electron capture cross section of the hole trap, can be determined.

DOI： 10.7567/APEX.11.071002

Characterization of carrier concentration and mobility of GaN bulk substrates by Raman scattering and infrared reflectance spectroscopies

Kanegae, K; Kaneko, M; Kimoto, T; Horita, M; Suda, J

JAPANESE JOURNAL OF APPLIED PHYSICS 57 巻 ( 7 ) 2018年7月

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

n-Type GaN bulk substrates with carrier concentrations (n) of 1016-1020 cm%3 were characterized by Raman scattering (350-5000 cm-1) and infrared reflectance (400-5000 cm%1) spectroscopies. Experimental spectra were fitted with the curves calculated from the dielectric function and carrier concentration and mobility of the GaN bulk. The obtained values agree well with the values from Hall-effect measurements for n of 1016-1019 cm-3 in Raman scattering measurements and for n of 1018-1020 cm-3 in infrared reflectance measurements.

DOI： 10.7567/JJAP.57.070309

Impacts of Finger Numbers on ON-State Characteristics in Multifinger SiC BJTs With Low Base Spreading Resistance

Asada Satoshi, Suda Jun, Kimoto Tsunenobu

IEEE TRANSACTIONS ON ELECTRON DEVICES 65 巻 ( 7 ) 頁： 2771 - 2777 2018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：IEEE Transactions on Electron Devices

Impacts of finger numbers on ON-state characteristics in multifinger 10-kV-class SiC bipolar junction transistors (BJTs), whose base spreading resistance is sufficiently reduced by using aluminum ion implantation, were investigated by performing TCAD simulations. Common-emitter current-voltage characteristics of the BJTs with different base current densities and carrier lifetimes in the collector layer were analyzed. The simulation results exhibited that the BJTs with fewer finger numbers could achieve superior characteristics owing to an expansion of a conductivity-modulated region and to a higher current density per finger. In addition, we showed that BJTs with a punchthrough structure have a potential to achieve superior characteristics suitable for power device applications under a certain condition, where strong conductivity modulation occurs. The presented results indicate that the appropriate finger numbers should be designed for a better performance of the multifinger SiC BJTs.

DOI： 10.1109/TED.2018.2834354

Theoretical analysis of Hall factor and hole mobility in p-type 4H-SiC considering anisotropic valence band structure

Tanaka H., Asada S., Kimoto T., Suda J.

JOURNAL OF APPLIED PHYSICS 123 巻 ( 24 ) 2018年6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 temperature dependencies of hole density and hole mobility of p-type 4H-SiC obtained by Hall effect measurement were theoretically analyzed taking account of its anisotropic valence band structure. The experimental Hall factor, which was derived from the ratio of theoretical hole density to experimental Hall hole density, was reproduced by theoretical Hall factor computed using the valence band structure and relaxation times of scattering mechanisms. The product of the theoretical Hall factor and drift mobility computed by the same transport model agreed well with the experimental Hall mobility. Based on analyses of the results, it was revealed that the temperature dependence of Hall factor can be explained by considering the anisotropic valence band structure along with consideration of anisotropic relaxation times. The contribution of each scattering mechanism was also discussed, and empirical formulas for Hall and drift mobilities are presented.

DOI： 10.1063/1.5025776

Franz-Keldysh effect in GaN p-n junction diode under high reverse bias voltage

Maeda, T; Narita, T; Kanechika, M; Uesugi, T; Kachi, T; Kimoto, T; Horita, M; Suda, J

APPLIED PHYSICS LETTERS 112 巻 ( 25 ) 2018年6月

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

Photocurrent induced by sub-bandgap light absorption due to the Franz-Keldysh effect was observed in GaN p-n junction diodes under a high reverse bias voltage. The photocurrent increased with the reverse bias voltage and the increase was found to be more significant as the wavelength approached the absorption edge of GaN. The photocurrent was calculated with consideration of light absorption induced by the Franz-Keldysh effect in the depletion layer. The calculated curves showed excellent agreement with the experimental curves. The photocurrent also increased with an increase in temperature and this could be quantitatively explained by the red-shift of the GaN absorption edge with the increase in temperature.

DOI： 10.1063/1.5031215

A comparative study on electrical characteristics of 1-kV pnp and npn SiC bipolar junction transistors

Okuda, T; Kimoto, T; Suda, J

JAPANESE JOURNAL OF APPLIED PHYSICS 57 巻 ( 4 ) 2018年4月

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

We investigate the electrical characteristics of 1-kV pnp SiC bipolar junction transistors (BJTs) and compare them with those of npn SiC BJTs. The base resistance, current gain, and blocking capability are characterized. It is found that the base resistance of pnp SiC BJTs is two orders of magnitude lower than that of npn SiC BJTs. However, the obtained current gains are low below unity in pnp SiC BJTs, whereas npn SiC BJTs exhibit a current gain of 14 without surface passivation. The reason for the poor current gain of pnp SiC BJTs is discussed.

DOI： 10.7567/JJAP.57.04FR04

Sources of carrier compensation in metalorganic vapor phase epitaxy-grown homoepitaxial n-type GaN layers with various doping concentrations

Sawada, N; Narita, T; Kanechika, M; Uesugi, T; Kachi, T; Horita, M; Kimoto, T; Suda, J

APPLIED PHYSICS EXPRESS 11 巻 ( 4 ) 2018年4月

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

The source of carrier compensation in metalorganic vapor phase epitaxy (MOVPE)-grown n-type GaN was quantitatively investigated by Halleffect measurement, deep-level transient spectroscopy, and secondary ion mass spectrometry. These analysis techniques revealed that there were at least three different compensation sources. The carrier compensation for samples with donor concentrations below 5 1016 cm3 can be explained by residual carbon and electron trap E3 (EC % 0.6 eV). For samples with higher donor concentrations, we found a proportional relationship between donor concentration and compensating acceptor concentration, which resulted from a third source of compensation. This is possibly due to the self-compensation effect.

DOI： 10.7567/APEX.11.041001

Impacts of energy relaxation process on quasi-ballistic hole transport capability in germanium and silicon nanowires

Tanaka H., Suda J., Kimoto T.

JOURNAL OF APPLIED PHYSICS 123 巻 ( 2 ) 2018年1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 quasi-ballistic hole transport in germanium and silicon nanowires was theoretically investigated by solving the Boltzmann transport equation taking account of phonon scattering in an atomistic framework. Comparison of quasi-ballistic hole transport capabilities between germanium and silicon nanowires showed that the transmission coefficients for the two materials are similar. Then, the behavior of forward and backward current fluxes was analyzed focusing on the impact of energy relaxation process. The slower energy relaxation of holes in germanium nanowires leads to a longer distance where backscattering enables holes to return to the source. This cancels the benefit of the longer mean free path of holes in germanium nanowires, resulting in similar transmission coefficients in germanium and silicon nanowires.

DOI： 10.1063/1.5010052

Deep-ultraviolet light emission from 4H-AlN/4H-GaN short-period superlattice grown on 4H-SiC(11(2)over-bar0)

Kaneko M., Ueta S., Horita M., Kimoto T., Suda J.

APPLIED PHYSICS LETTERS 112 巻 ( 1 ) 2018年1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：Applied Physics Letters

AlN/GaN short-period superlattices (SPSLs) were grown on 4H-SiC(112-0) substrates with a 4H-AlN template layer. The thickness of the GaN layers was controlled to be less than 1 nm to suppress the generation of extended defects. The stacking fault and threading dislocation density were found to be 3 × 105 cm-1 and 6 × 107 cm-2, respectively, which were as low as those for a 4H-AlN single layer. The superlattice replicated the polytype of the underlying 4H-AlN layer (4H-SiC substrate), meaning that a 4H-AlN/4H-GaN SPSL was grown. Roomerature cathodoluminescence measurements revealed that the 4H-AlN/4H-GaN SPSLs exhibited intense luminescence in the deep ultraviolet region of 4.4-5.0 eV, depending on the GaN layer thickness. The emission wavelengths of the SPSLs fairly agreed with the estimation based on the Kronig-Penney model.

DOI： 10.1063/1.5006435

Effects of parasitic region in SiC bipolar junction transistors on forced current gain

Asada S., Suda J., Kimoto T.

Materials Science Forum 924 MSF 巻頁： 629 - 632 2018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

Effects of a parasitic region in SiC BJTs on conductivity modulation and a forced current gain (βF) were investigated by using TCAD simulation with various device structures. By introducing an Al+-implanted region below the base parasitic region, βF can be improved because the implanted region can reduce the base spreading resistance, leading to alleviation of debiasing effect. βF in devices with various parasitic areas, whose base spreading resistances were reduced by the Al+-implantation, were compared. We found that βF can be enhanced by expanding the parasitic area if the base spreading resistance is sufficiently reduced. The higher βF is attributed to an expanded conductivity-modulated region. The collector current spreading in the collector layer and hole injection from the parasitic region as well as from the intrinsic region can play a role to evoke conductivity modulation. Thus, the larger parasitic region can expand the conductivity-modulated region, which results in expansion of an active area and the enhancement of βF, though a higher base voltage is required.

DOI： 10.4028/www.scientific.net/MSF.924.629

Parallel-Plane Breakdown Fields of 2.8-3.5 MV/cm in GaN-on-GaN p-n Junction Diodes with Double-Side-Depleted Shallow Bevel Termination

Maeda, T; Narita, T; Ueda, H; Kanechika, M; Uesugi, T; Kachi, T; Kimoto, T; Horita, M; Suda, J

2018 IEEE INTERNATIONAL ELECTRON DEVICES MEETING (IEDM) 2018年

Comparison between GaN and SiC From the viewpoint of vertical power devices

Suda J.

CS MANTECH 2018 - 2018 International Conference on Compound Semiconductor Manufacturing Technology 2018年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：CS MANTECH 2018 - 2018 International Conference on Compound Semiconductor Manufacturing Technology

Thanks to superior materials properties, GaN has great potential as the next-generation power devices. The author will discuss challenges for GaN vertical devices by referring SiC technologies, which has over 20 years history.

Theoretical analysis of quasi-ballistic hole transport in Ge and Si nanowires focusing on energy relaxation process

Tanaka H., Suda J., Kimoto T.

2017 Silicon Nanoelectronics Workshop, SNW 2017 2017-January 巻頁： 35 - 36 2017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：2017 Silicon Nanoelectronics Workshop, SNW 2017

The quasi-ballistic hole transport capabilities of Ge and Si NWs were calculated using atomistic electron-phonon coupling and Boltzmann transport equation. Analyzing the forward and backward current fluxes, it was shown that the positive impact of high mobility of Ge is canceled by its slower energy relaxation, which results in comparable transmission coefficients and current transport capabilities between Ge and Si NWs.

DOI： 10.23919/SNW.2017.8242284

Carrier Lifetimes in Lightly-Doped p-Type 4H-SiC Epitaxial Layers Enhanced by Post-growth Processes and Surface Passivation

Okuda T., Miyazawa T., Tsuchida H., Kimoto T., Suda J.

JOURNAL OF ELECTRONIC MATERIALS 46 巻 ( 11 ) 頁： 6411 - 6417 2017年11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

We investigated limiting factors of carrier lifetimes and their enhancement by post-growth processes in lightly-doped p-type 4H-SiC epitaxial layers (NA ∼ 2 × 1014 cm−3). We focused on bulk recombination, surface recombination, and interface recombination at the epilayer/substrate, respectively. The carrier lifetime of 2.8 μs in an as-grown epilayer was improved to 10 μs by the combination of VC-elimination processes and hydrogen annealing. By employing surface passivation with deposited SiO2 followed by POCl3 annealing, a long carrier lifetime of 16 μs was obtained in an oxidized epilayer. By investigating carrier lifetimes in a self-standing p-type epilayer, it was revealed that the interface recombination at the epilayer/substrate was smaller than the surface recombination on a bare surface. We found that the VC-elimination process, hydrogen annealing, and surface passivation are all important for improving carrier lifetimes in lightly-doped p-type epilayers.

DOI： 10.1007/s11664-017-5677-4

Analysis of quasi-ballistic hole transport capability of Ge and Si nanowire pMOSFETs by a quantum-corrected Boltzmann transport equation

Tanaka H., Suda J., Kimoto T.

International Conference on Simulation of Semiconductor Processes and Devices, SISPAD 2017-September 巻頁： 277 - 280 2017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：International Conference on Simulation of Semiconductor Processes and Devices, SISPAD

The quasi-ballistic hole transport capabilities of Ge and Si nanowire pMOSFETs were analyzed based on a quantum-corrected Boltzmann transport equation. A new formalism of quantum-correction potential was proposed, and using this model, the current drive capabilities of Ge and Si nanowire pMOSFETs were compared. Though the ON-current was larger in the Ge nanowire pMOSFET, the transmission coefficients are similar between Ge and Si, because the higher hole mobility of Ge is canceled by its slower energy relaxation. Thus, the larger current of the Ge nanowire pMOSFET was attributed to its larger injection current. The impact of device geometry on the performance was also investigated, and the [110]-oriented Ge nanowire pMOSFET with a 15 nm gate length exhibited the highest performance among the devices considered in this study.

DOI： 10.23919/SISPAD.2017.8085318

Characterization of lightly-doped n- and p-type homoepitaxial GaN on free-standing substrates

Horita M., Suda J.

IMFEDK 2017 - 2017 International Meeting for Future of Electron Devices, Kansai 頁： 86 - 87 2017年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IMFEDK 2017 - 2017 International Meeting for Future of Electron Devices, Kansai

Hall-effect measurements for n-type and p-type GaN with low doping concentration are presented. The GaN layers were grown by metal-organic vapor phase epitaxy on hydride-vapor-phase-epitaxy-grown free-standing GaN substrates. For n-GaN, the origin of acceptor which compensating donor is not only C but also native defects for the Si doping concentration of 1016 cm-3 level. The electron mobility is mainly limited by ionized impurity scattering or polar optical phonon scattering in the temperature less or higher than 200 K, respectively. For p-GaN, lightly Mg doping of mid 1016 cm-3 was achieved, which shows the donor concentration of 3.2×1016 cm-3 and the mobility of 31 cm2/Vs at 300 K.

DOI： 10.1109/IMFEDK.2017.7998055

　前のページ - 次のページ　

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22