Search

Your search keyword '"Yamahata, S."' showing total 123 results
Start Over Author "Yamahata, S."
123 results on '"Yamahata, S."'

1. High-speed and high-reliability InP-based HBTs with a novel emitter

Author

Kashio, N., Kurishima, K., Fukai, Y.K., Ida, M., and Yamahata, S.

Subjects
Gallium arsenide -- Electric properties, Gallium arsenide -- Structure, Indium -- Electric properties, Reliability (Engineering) -- Analysis, Semiconductor doping -- Analysis, Business, Electronics, Electronics and electrical industries
Published
2010

2. Measurement of valence-band offsets of InAlN/GaN heterostructures grown by metal-organic vapor phase epitaxy.

Author

Akazawa, M., Gao, B., Hashizume, T., Hiroki, M., Yamahata, S., and Shigekawa, N.

Subjects
HETEROSTRUCTURES, EPITAXY, METAL organic chemical vapor deposition, X-ray photoelectron spectroscopy, CONDUCTION bands
Abstract

The valence band offsets, ΔEV, of In0.17Al0.83N/GaN, In0.25Al0.75N/GaN, and In0.30Al0.70N/GaN heterostructures grown by metal-organic vapor phase epitaxy were evaluated by using x-ray photoelectron spectroscopy (XPS). The dependence of the energy position and the full width at half maximum of the Al 2p spectrum on the exit angle indicated that there was sharp band bending caused by the polarization-induced electric field combined with surface Fermi-level pinning in each ultrathin InAlN layer. The ΔEV values evaluated without taking into account band bending indicated large discrepancies from the theoretical estimates for all samples. Erroneous results due to band bending were corrected by applying numerical calculations, which led to acceptable results. The evaluated ΔEV values were 0.2±0.2 eV for In0.17Al0.83N/GaN, 0.1±0.2 eV for In0.25Al0.75N/GaN, and 0.0±0.2 eV for In0.30Al0.70N/GaN. Despite the large decrease of around 1.0 eV in the band gap of InAlN layers according to the increase in the In molar fraction, the decrease in ΔEV was as small as 0.2 eV. Therefore, the change in band-gap discontinuity was mainly distributed to that in conduction band offset. [ABSTRACT FROM AUTHOR]

Published
2011
Full Text
View/download PDF

3. Al0.44Ga0.56N spacer layer to prevent electron accumulation inside barriers in lattice-matched InAlN/AlGaN/AlN/GaN heterostructures

Author

Akazawa, M., Gao, B., Hashizume, T., Hiroki, M., Yamahata, S., Shigekawa, N., Akazawa, M., Gao, B., Hashizume, T., Hiroki, M., Yamahata, S., and Shigekawa, N.

Abstract

The barrier structure in lattice-matched InAlN/GaN heterostructures with AlGaN-based spacer layers grown by metal organic vapor phase epitaxy was studied by the capacitance-voltage (C-V) method. To investigate the characteristics under positive bias, an Al2O3 overlayer was added. The C-V characteristic of a sample with an Al0.38Ga0.62N (5 nm)/AlN (0.75 nm) double spacer layer exhibited an anomalous saturation at a value far below the insulator capacitance under positive bias, which indicated electron accumulation at the InAlN/AlGaN interface. The C-V characteristic of an alternative sample with a single Al0.44Ga0.56N (1.5 nm) spacer layer did not exhibit the anomalous saturation.

Published
2011

4. Small valence-band offset of In0.17Al0.83N/GaN heterostructure grown by metal-organic vapor phase epitaxy

Author

Akazawa, M., Matsuyama, T., Hashizume, T., Hiroki, M., Yamahata, S., Shigekawa, N., Akazawa, M., Matsuyama, T., Hashizume, T., Hiroki, M., Yamahata, S., and Shigekawa, N.

Abstract

The valence-band offset of a lattice-matched In0.17Al0.83N/GaN heterostructure grown by metal-organic vapor phase epitaxy (MOVPE) was investigated by x-ray photoelectron spectroscopy (XPS). Atomic force microscopy and angle-resolved XPS indicated that a thin In0.17Al0.83N (2.5 nm) layer was successfully grown by MOVPE on GaN. The XPS result showed that the valence band offset was 0.2 ± 0.3 eV. This result indicates that the conduction-band offset at the In0.17Al0.83N/GaN interface is large, i.e., 0.9 to 1.0 eV, and occupies a large part of the entire band discontinuity.

Published
2010

5. Small valence-band offset of In0.17Al0.83N/GaN heterostructure grown by metal-organic vapor phase epitaxy

Author

1000030212400, Akazawa, M., Matsuyama, T., Hashizume, T., Hiroki, M., Yamahata, S., Shigekawa, N., 1000030212400, Akazawa, M., Matsuyama, T., Hashizume, T., Hiroki, M., Yamahata, S., and Shigekawa, N.

Abstract

The valence-band offset of a lattice-matched In0.17Al0.83N/GaN heterostructure grown by metal-organic vapor phase epitaxy (MOVPE) was investigated by x-ray photoelectron spectroscopy (XPS). Atomic force microscopy and angle-resolved XPS indicated that a thin In0.17Al0.83N (2.5 nm) layer was successfully grown by MOVPE on GaN. The XPS result showed that the valence band offset was 0.2 ± 0.3 eV. This result indicates that the conduction-band offset at the In0.17Al0.83N/GaN interface is large, i.e., 0.9 to 1.0 eV, and occupies a large part of the entire band discontinuity.

Published
2010

Catalog

Books, media, physical & digital resources
See catalog results