Hideo Kawanishi

Epitaxial growth of high quality BAlGaN quaternary lattice matched to AlN on 6H–SiC substrate by LP-MOVPE for deep-UV emission

Abstract BAlGaN and (BAlGaN/AlN) multi-quantum-well (MQW) structures were grown on a 6H–SiC substrate by low-pressure metalorganic vapor phase epitaxy. Boron compositions of the BAlGaN estimated by Auger electron spectroscopy analysis were in the range of 1.5–13%. Photoluminescence (PL) spectra at ≈ 260xa0nm from the (BAlGaN/AlN) MQW were obtained at room temperature. Moreover, PL spectra of the MQW were successfully improved by decreasing the lattice mismatch between the BAlGaN well and the AlN barrier layers to +0.7xa0%.

Deposition of Amorphous GaN by Compound Source Molecular Beam Epitaxy for Electroluminescent Devices

Amorphous GaN films were deposited using compound source MBE. GaN powder was used as the source material and no additional nitrogen sources were supplied. Although the N/Ga ratio in the layers deposited at temperatures lower than 400 °C was low, an increase of the substrate temperature improved the N/Ga ratio. The emission peaks of their photoluminescence spectra originated around the band edge of hexagonal GaN. Electroluminescent devices based on amorphous GaN were fabricated and were found to show UV emission. Amorphous GaN is one of the candidate materials for light-emitting devices operating in the UV to the blue spectral regions.

GaN growth by compound source molecular beam epitaxy

Abstract The compound-source molecular beam epitaxy of GaN on (0xa00xa00xa01) 6H-SiC was investigated. GaN powder was used as a source material. The source beams of GaN were supplied on the surface of substrates at source temperatures >900°C. The epitaxial growth of GaN was achieved at the low growth temperature of 570°C.

GaN Growth by Compound Source MBE Using GaN Powder

Growth of GaN at low temperatures less than 570 °C was investigated using the molecular beam epitaxy technique. GaN powder was used as a source material. The crystalline structure of GaN layers grown below 450°C was amorphous, which was estimated using RHEED patterns. Bluish-white light from the amorphous GaN layers was observed under UV light excitation at room temperature.

Carbon-doped p-type (0001) plane AlGaN (Al=0.06 to 0.55) with high hole density

In this paper, promising experimental results for the p-type electrical properties of carbon-doped (C-doped) AlGaN are discussed. P-type conductivity was experimentally achieved in C-doped (0001) plane AlGaN layers with from a small amount to 55% solid Al composition, but not in (0001) plane GaN. The maximum free hole density (determined by van der Pauw geometry-Hall effect measurement) achieved for an AlGaN layer with 10% solid Al composition was p= 3.2 x 1018 cm-3. The maximum net ionized acceptor densities (NIAD = (NA --ND +)), which were determined by capacitance-voltage measurement, for AlGaN with 6, 10, 27, and 55% solid Al compositions, were all in the range of (3-7) x 1018 cm-3. Moreover, the electrical activity of the carbon acceptors was estimated to be 55-71% from the NIAD and secondary-ion microprobe mass spectrometry analysis data on the carbon concentration. Activation energy of carbon acceptors was estimated to be 22-30 meV from this electrical activity. On the other hand, optical property of C-doped AlGaN was compared with undoped AlGaN. Then we found new emission, which related to carbon acceptors, at smaller energy side by 29-35 meV from band edge-emission of the AlGaN. A p-n junction was also fabricated using the C-doped p-type AlGaN.

“Structure and properties of deep-UV AlGaN MQW laser”

Structure and properties of UV and deep-UV AlGaN MQW laser grown on c-plane SiC substrate are discussed. TM-mode lasing was demonstrated in deep-UV spectrum region. This is originated in band structure of AlGaN.