Makoto Kurimoto

Band-Gap Energy and Effective Mass of BGaN

The band-gap energies and effective masses of boron gallium nitride (BGaN) ternaries were estimated. The band-gap energies of BxGa1-xN ternaries increase proportionally with the boron composition x. However, the effective masses of electrons and holes in BGaN ternaries are almost equal to those of GaN. We have fabricated BGaN layers on 6H–SiC substrates using metal-organic vapor phase epitaxy (MOVPE). We examined the photoluminescence spectra of these layers. The band-gap energies and effective masses estimated using the photoluminescence results are consistent with those estimated theoretically.

Dependence of Crystal Quality on Residual Strain in Strain-Controlled Thin AlN Layer Grown by Metalorganic Vapor Phase Epitaxy

Strain-controlled AlN layers were grown on (0001) 6H–SiC with a (GaN/AlN) buffer layer by metalorganic vapor phase epitaxy using an alternating-source-feeding technique (ASF). The successful strain and quality control of the thin AlN layer were experimentally demonstrated down to 0.05 µm by changing the growth conditions of the (GaN/AlN) buffer layer. The quality of the AlN layer was evaluated by not only X-ray diffraction (θ-2θ) but an X-ray rocking curve (ω-scan) from the viewpoint of c-axis tilting. The crystal quality was dependent on the residual strain in the AlN layer. The (GaN/AlN)-buffer layer is effective in improving the quality of the AlN layer.

Tensile Strain Introduced in AlN Layer Grown by Metal-Organic Vapor-Phase Epitaxy on (0001) 6H-SiC with (GaN/AlN) Buffer

An AlN layer with tensile strain along the a-axis was grown on a (0001) 6H-SiC substrate with a (GaN/AlN) buffer layer by metal-organic vapor-phase epitaxy using an alternating source feeding technique. It was experimentally demonstrated that the strain in the AlN layer was affected by the buffer layer structure. On the other hand, the AlN layer grown directly on a substrate without the buffer layer exhibits compressive strain along the a-axis. Strain control in the AlN layer by adjusting the buffer layer structure is proposed.

Possibility of Strain Control in AlN Layer Grown by MOVPE on (0001) 6H‐SiC with GaN/AlN Buffer

A tensile-strained AlN layer along the a-axis was grown on a (0001) 6H-SiC substrate with a (GaN/AlN) buffer layer by metalorganic vapor phase epitaxy using an alternating source feeding (ASF) technique. It was experimentally demonstrated that the strain in the AlN layer was affected by the growth conditions of the buffer layer. On the other hand, the AlN layer grown directly on a substrate without the buffer layer exhibits compressive strain along the a-axis. Strain control in the AlN layer using the ASF buffer is proposed.

Room-Temperature Photoluminescence from BAlGaN-Based Double or Single Heterostructures for UV Laser Diode

A BGaN/AlN double heterostructure or BAlGaN/AlN single was grown on 6H-SiC substrate by metalorganic vapor phase epitaxy (MOVPE). The relation between the band-gap energy and boron composition was experimentally determined for BGaN. Photoluminescence (PL) spectra were observed with 2.7% boron composition at room temperature. The PL spectrum of BAlGaN, which was near the band-edge, was observed.

Improved Optical Quality of BAlGaN/AlN MQW Structure Grown on 6H-SiC Substrate by Controlling Residual Strain Using Multi-Buffer Layer

BAlGaN and (BAlGaN/AlN) multi-quantum-wells (MQWs) structure were grown on 6H-SiC substrate by a low-pressure metalorganic vapor phase epitaxy (LP-MOVPE). Estimated boron compositions of the BAlGaN quantum wells by an Auger electron spectroscopy (AES) analysis were 0% to 13%. Photoluminescence (PL) spectra around 260 nm were observed at room temperature. The full-width at half maximum (FWHM) of PL spectra for BAlGaN/AlN MQW structure(with 2% of boron) was narrowed from 360 meV to 179 meV, as the residual strain in the BAlGaN well layer was decreased from 1.3% to 1.0% by increasing the Al content in the quantum wells.