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Nozaki, Mikito*; Terashima, Daiki*; Yoshigoe, Akitaka; Hosoi, Takuji*; Shimura, Takayoshi*; Watanabe, Heiji*
Japanese Journal of Applied Physics, 59(SM), p.SMMA07_1 - SMMA07_7, 2020/07
Times Cited Count：2 Percentile：12.12(Physics, Applied)AlGaN/GaN metal-oxide-semiconductor (MOS) structures were fabricated by low-power inductively coupled plasma reactive ion etching and chemical vapor deposition of SiO
dielectrics on the etched surfaces, and they were systematically investigated by physical and electrical characterizations in an effort to develop a low-damage recessed gate process. The comprehensive research demonstrates the significant advantages of the proposed low-damage recessed gate process for fabricating next-generation AlGaN/GaN MOS-HFET devices.
Laube, M.*; Pensl, G.*; Lee, K. K.; Oshima, Takeshi
Materials Science Forum, 457-460, p.1381 - 1384, 2004/10
The electrical properties of n-channel 6H-SiC MOSFETs have been studied by temperature-dependent current-voltage and Hall effect measurements. The MOS transistors are either wet (sample A) or dry oxidized followed by a post-annealing step at 1100
C and a pyrogenic reoxidation at 800C (sample B). Higher drain transconductance and saturation currents are observed in sample B. The Hall effect investigations show that this improvement in the performance of the MOS transistors (sample B) is caused by a lower degree of trapping of free electrons. The density of interface traps D
close to the conduction band edge has been determined from the shift of the threshold voltage V
as a function of the temperature and from the Hall effect results. D is about two times lower in sample B. The room temperature value of the electron Hall mobility is determined to be about 60 cm
/Vs for both samples; it increases with decreasing temperature.
-ray irradiationOshima, Takeshi; Ito, Hisayoshi
Proceedings of the 6th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-6), p.191 - 194, 2004/10
no abstracts in English
Oshima, Takeshi; Lee, K. K.; Ishida, Yuki*; Kojima, Kazutoshi*; Tanaka, Yasunori*; Takahashi, Tetsuo*; Yoshikawa, Masahito; Okumura, Hajime*; Arai, Kazuo*; Kamiya, Tomihiro
Materials Science Forum, 457-460(Part2), p.1405 - 1408, 2004/06
The electrical characteristics of cubic silicon carbide (3C-SiC) Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) with the current direction in the inversion layer perpendicular to [-110] ([-110]-perpendicular MOSFETs) were compared to those of 3C-SiC MOSFETs with the current direction in the inversion layer parallel to [-110] ([-110]-parallel MOSFETs). The threshold voltage (V
) for both MOSFETs shows -0.5 V although enhancement type MOSFETs were designed. The values of channel mobility which was estimated from linear region of drain current (I
) - drain voltage (V) curves are 230 cm/Vs for [-110]-perpendicular MOSFETs and 215 cm/Vs for [-110]-parallel MOSFETs, indicating no significant difference between both MOSFETs. The value of I for [-110]-perpendicular MOSFETs is of order of 10-8 A at V = 10V and gate voltage (V
) of -2V. However, for [-110]-parallel MOSFETs, I shows of order of -10-6 A at V = 10V and V = -2V.
Laird, J. S.; Hirao, Toshio; Onoda, Shinobu*; Kamiya, Tomihiro
Nuclear Instruments and Methods in Physics Research B, 219-220, p.1015 - 1021, 2004/06
Times Cited Count：7 Percentile：45.06(Instruments & Instrumentation)no abstracts in English
thin filmsLee, H.-S.*; Okada, Hiroshi*; Wakahara, Akihiro*; Yoshida, Akira*; Oshima, Takeshi; Ito, Hisayoshi; Kawakita, Shiro*; Imaizumi, Mitsuru*; Matsuda, Sumio*
Physica Status Solidi (A), 199(3), p.471 - 474, 2003/10
Times Cited Count：3 Percentile：21.31(Materials Science, Multidisciplinary)no abstracts in English
Oshima, Takeshi; Lee, K. K.; Ishida, Yuki*; Kojima, Kazutoshi*; Tanaka, Yasunori*; Takahashi, Tetsuo*; Yoshikawa, Masahito; Okumura, Hajime*; Arai, Kazuo*; Kamiya, Tomihiro
Japanese Journal of Applied Physics, Part 2, 42(6B), p.L625 - L627, 2003/06
Times Cited Count：39 Percentile：77.38(Physics, Applied)The n-channel Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) were fabricated on cubic silicon carbide (3C-SiC) epitaxial layers grown on 3C-SiC substrates. The gate oxide of the MOSFETs was formed using pyrogenic oxidation at 1100C. The 3C-SiC MOSFETs showed enhancement type behaviors after annealing at 200C for 30 min in argon atmosphere. The maximum value of the effective channel mobility of the 3C-SiC MOSFETs was 260 cm/Vs. The leakage current of gate oxide was of a few tens of nA/cm at an electric field range below 8.5 MV/cm, and breakdown began around 8.5 MV/cm.
Lee, K. K.; Oshima, Takeshi; Ito, Hisayoshi
Materials Science Forum, 389-393, p.1097 - 1100, 2002/05
The effect of gamma-ray irradiation on electrical characteristics of n-channel and p-chanel enhancement type 6H-SiC MOSFET was studied. The gate oxide of the MOSFETs were formed using pyrogenic condition. Gamma-ray irradiation was carried out at room temperature at 8.8 kGy(SiO)/hour. The channel mobility and thrshold voltage for the MOSFETs were estimated from I-V and I-V curves, respectively. The channel mobility for n-channel one does not change up to 1MGy. The channel mobility for p-channel one increases around 40 kGy and decreases above 40 kGy. This behavior is interpreted in terms of the compensation of intrinsic interface traps by the interface traps generated by irradiation. The fluctuation of thershold voltage for n-channel one by irradiation is less than 0.5V. For p-channel one, the threshold voltage decreases with increasing irradiation dose.
Oshima, Takeshi; Lee, K. K.; Oi, Akihiko; Yoshikawa, Masahito; Ito, Hisayoshi
Materials Science Forum, 389-393, p.1093 - 1096, 2002/05
Gamma-ray irradiation effects on the electrical characteristics such as threshold voltage (V) and channel mobility (
) for 6H-SiC MOSFETs were studied.The gate oxide of the MOSFETs were annealed in hydrogen at 700 
or steam at 800 in fabrication process to improve the initial electrical characteristics of the MOSFETs.As for the hydrogen-annealed MOSFETs,V was changed from 0.9V to 3.1 V by irradiation at 530kGy. decreased after irradiation above 60 kGy. As for the steam-annealed MOSFETs,V was changed from 2.7 to 3.3 V by irradiation at 530kGy. decreased above 180 kGy. This indicates that radiation resistance for the steam-annealed MOSFETs is higher than that for the hydrogen-annealed MOSFETs.
Oi, Akihiko; Oshima, Takeshi; Yoshikawa, Masahito; Lee, K. K.; Iwami, Motohiro*; Ito, Hisayoshi
Materials Science Forum, 389-393, p.831 - 834, 2002/05
no abstracts in English
-ray irradiation on the characteristics of 6H silicon carbide metal-oxide-seminocductor field effect transistor with hydrogen-annealed gate oxideOshima, Takeshi; Ito, Hisayoshi; Yoshikawa, Masahito
Journal of Applied Physics, 90(6), p.3038 - 3041, 2001/09
Times Cited Count：43 Percentile：81.56(Physics, Applied)The effect of gamma-ray irradiation on the electrical characteristics of 6H-SiC MOSFETs with hydrogen-annealed gate oxide was studied.The concentration of radiation induced interface traps increases with increasing gamma-ray dose, however, the number of interface traps is 1/100 smaller than it in Si MOSFET. The channel mobility for 6H-SiC MOSFET does not change at 30 kGy, and it becomes the half of the initial value (52 cm2/Vs) at 500 kGy.Since the channel mobility for Si MOSFET shows 50 % of the initial value at 10 kGy, this indicates that tha radiation resistance of SiC MOSFET is stronger than that of Si MOSFET. As for the cahnnel mobility vs. the concentration of radiation induced interface traps, the same behavior shows for Si and SiC MOSFETs. This suggest the channel mobility in SiC as well as Si decreases by the generation of interface traps which act as scattring centers.
Oshima, Takeshi; Yoshikawa, Masahito; Ito, Hisayoshi; Kojima, Kazutoshi; Okada, Sohei; Nashiyama, Isamu
Materials Science Forum, 338-342, p.1299 - 1302, 2000/00
no abstracts in English
Oshima, Takeshi; Morita, Yosuke; Nashiyama, Isamu; Kawasaki, Osamu*; Hisamatsu, Tadashi*; Matsuda, Sumio*; Nakao, Tetsuya*; Wako, Yoshihito*
JAERI-Conf 97-003, p.256 - 260, 1997/03
no abstracts in English
Ito, Hisayoshi; Yoshikawa, Masahito; Nashiyama, Isamu*; *; Okumura, Hajime*; Yoshida, Sadafumi*
Amorphous and Crystalline Silicon Carbide III and Other Group IV-IV Materials, p.143 - 148, 1992/00
no abstracts in English
Ito, Hisayoshi; Yoshikawa, Masahito; Morita, Yosuke; Nashiyama, Isamu*; *; Yoshida, Sadafumi*
EIM-89-129, p.1 - 10, 1989/12
no abstracts in English
solid solutions; ; ;
Journal of Nuclear Materials, 150, p.233 - 237, 1987/00
Times Cited Count：6 Percentile：55.64(Materials Science, Multidisciplinary)no abstracts in English
