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Chōfugaoka, Japan

Ando Y.,Tomei Diamond Co. | Kamano T.,Aoyama Gakuin University | Suzuki K.,TOPLAS ENGINEERING Co. | Sawabe A.,Aoyama Gakuin University
Japanese Journal of Applied Physics | Year: 2012

Epitaxial lateral overgrowth (ELO) of diamond on Ir(001)/MgO(001) substrates was demonstrated by using a patterned nucleation and growth method. Epitaxial nucleation areas of fine line shape aligned with various crystal orientations were prepared on an Ir(001) surface before diamond growth. The growth rate of the diamonds in the lateral direction markedly changed depending on both the crystal orientation and the growth conditions. A lateral/vertical growth rate ratio of approximately 4.9 was obtained. The full widths at half maximum of the diamond Raman peak observed at the laterally grown areas were approximately threefold better than that of the vertically grown areas on the nucleation sites. © 2012 The Japan Society of Applied Physics.


Ichikawa K.,Aoyama Gakuin University | Kodama H.,Aoyama Gakuin University | Suzuki K.,TOPLAS ENGINEERING Co. | Sawabe A.,Aoyama Gakuin University
Thin Solid Films | Year: 2016

The classification of etch pits formed by hydrogen plasma etching on heteroepitaxial diamond has been done by cross-sectional transmission electron microscope (TEM). We demonstrated that the origin of etch pit was mainly [001] threading dislocation. From invisibility criterion of dislocation contrast in TEM observation, this dislocation was identified as edge and 45° mixed dislocation. The correlation between dislocation types and etch pit shape was discussed. © 2016 Elsevier B.V. All rights reserved.


Yoshikawa T.,Aoyama Gakuin University | Yoshikawa T.,Fraunhofer Institute for Applied Solid State Physics | Kodama H.,Aoyama Gakuin University | Kono S.,Aoyama Gakuin University | And 3 more authors.
Thin Solid Films | Year: 2015

The potential of patterned nucleation growth (PNG) technique to control the wafer bowing of free-standing heteroepitaxial diamond films was investigated. The heteroepitaxial diamond (100) films were grown on an Ir(100) substrate via PNG technique with different patterns of nucleation regions (NRs), which were dot-arrays with 8 or 13 μm pitch aligned to < 100 > or < 110 > direction of the Ir(100) substrate. The wafer bows and the local stress distributions of the free-standing films were measured using a confocal micro-Raman spectrometer. For each NR pattern, the stress evolutions within the early stage of diamond growth were also studied together with a scanning electron microscopic observation of the coalescing diamond particles. These investigations revealed that the NR pattern, in terms of pitch and direction of dot-array, strongly affects the compressive stress on the nucleation side of the diamond film and dominantly contributes to the elastic deformation of the free-standing film. This indicates that the PNG technique with an appropriate NR pattern is a promising solution to fabricate free-standing heteroepitaxial diamond films with extremely small bows. © 2015 Elsevier B.V. All rights reserved.


Kono S.,Aoyama Gakuin University | Nohara T.,Aoyama Gakuin University | Nohara T.,Sumitomo Electric | Abe S.,Aoyama Gakuin University | And 6 more authors.
Japanese Journal of Applied Physics | Year: 2012

A phosphorus (P)-doped n-type heteroepitaxial diamond (001) sample was grown in a DC-plasma chemical-vapor-deposition chamber. The crystalline properties of incorporated phosphorus were examined by cathode luminescence. Hall-effect measurement of the sample was performed for the temperature range of 293-870 K. The results of these measurements showed that the bulk properties of the n-type sample are comparable to those of previously reported homoepitaxial P-doped n-type diamond (001) samples. The work function of the heteroepitaxial sample was measured by photoemission electron microspectroscopy. The Fermi-level positions at the surface and at a Au Schottky junction of the sample were determined by X-ray photoelectron spectroscopy. Knowing the bulk properties and the critical values of the energy band structure, the whole energy band diagrams at the surface and at the Schottky junction of the sample were evaluated by solving the Poisson equation. The resulting surface electronic structure of the sample was qualitatively different from those of the previously reported H-terminated P-doped n-type diamond (111) surface and heavily P-doped H- and O-terminated diamond (111) surfaces. The presence of ∼0.02ML of Sn impurity is tentatively ascribed to the peculiarity of the surface electronic structure of the heteroepitaxial sample. The Schottky barrier height of ∼4.2 eV determined for the present sample was consistent with those of previously reported n-type diamond (111) and (001) samples. It is noted that the Schottky barrier height may be determined by the Fermi-level pinning states at the junctions irrespective of the type of dopant to diamond. © 2012 The Japan Society of Applied Physics.


Washiyama S.,Aoyama Gakuin University | Mita S.,Aoyama Gakuin University | Suzuki K.,TOPLAS ENGINEERING Co. | Sawabe A.,Aoyama Gakuin University
Applied Physics Express | Year: 2011

The coalescence of epitaxial lateral overgrowth (ELO)-diamonds from stripe-patterned diamond nucleation formed on (001) Ir/MgO has been investigated. Scanning electron microscopy showed only continuous macro steps on the coalesced ELO-diamond layers. Cross-sectional Raman mappings for the 1332 cm-1 diamond peak revealed that ELO regions including coalescence boundaries had a lower full width at half maximum value than regions vertically grown on a nucleation layer. Continuously observed strong tensile strains in ELO regions indicated that additional defect formation to relax the lattice was suppressed even after the coalescence. These results showed that the ELO diamond process could be used to obtain high crystalline diamond films by heteroepitaxy. © 2011 The Japan Society of Applied Physics.

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