Publications

@article{2009yatsuiGaNAPB,

title = {Increased spatial homogeneity in a light-emitting InGaN thin film using optical near-field desorption},

author = {Takashi Yatsui and Shunsuke Yamazaki and Keiichi Ito and Hiroshi Kawamura and Michinobu Mizumura and Tadashi Kawazoe and Motoichi Ohtsu},

doi = {10.1007/s00340-009-3757-8},

year  = {2009},

date = {2009-10-01},

journal = {Applied Physics B},

volume = {97},

number = {2},

pages = {375-378},

publisher = {Springer Nature},

abstract = {We report a self-assembly method that produces greater spatial uniformity in InGaN thin films using optical near-field desorption. Spatial homogeneity in the In fraction was reduced by introducing additional light during the photo-enhanced chemical vapor deposition of InGaN. Near-field desorption of InGaN nanoparticles, upon addition depended on the In content of the film, and the photon energy of the illumination source determined the energy of the emitted photons. Since this deposition method is based on a photo-desorption reaction, it can easily be applied to other deposition techniques and used with other semiconductor systems.},

keywords = {First, GaN, Nanophotonic fabrication, Near-field effect, Self-assembly},

pubstate = {published},

tppubtype = {article}

}

@article{Yamazaki_2009,

title = {Room-Temperature Growth of UV-Emitting Dendritic GaN Fractal Nanostructures Using Photochemical Vapor Deposition},

author = {Shunsuke Yamazaki and Takashi Yatsui and Motoichi Ohtsu},

doi = {10.1143/apex.2.031004},

year  = {2009},

date = {2009-03-01},

journal = {Applied Physics Express},

volume = {2},

number = {3},

pages = {031004},

publisher = {IOP Publishing},

abstract = {A dendritic gallium nitride (GaN) structure was grown at room temperature using photochemical vapor deposition with trimethylgallium and ammonia as the source materials. The sample was investigated by a scanning electron microscope and photoluminescence (PL). Its morphology was evaluated using fractal analysis. The surface morphology of the deposited film had dendritic nanostructures similar in morphology to the diffusion-limited aggregation. Dendritic GaN had a strong PL spectrum with a peak energy of 3.55 eV at 5 K, indicating the quantum size effect. Using the box-counting method, the fractal dimension of the dendritic GaN nanostructure was calculated to be approximately 1.7.},

note = {The paper was highlighted in Nature Photonics Vol.3, 252 (2009)},

keywords = {Fractal, GaN, Nanophotonic fabrication},

pubstate = {published},

tppubtype = {article}

}

@article{Yamazaki_2008,

title = {Room-Temperature Growth of UV-Emitting GaN with a Hexagonal Crystal-Structure Using Photochemical Vapor Deposition},

author = {Shunsuke Yamazaki and Takashi Yatsui and Motoichi Ohtsu},

doi = {10.1143/apex.1.061102},

year  = {2008},

date = {2008-06-01},

journal = {Applied Physics Express},

volume = {1},

number = {6},

pages = {061102},

publisher = {IOP Publishing},

abstract = {The room-temperature (RT) growth of ultraviolet-emitting hexagonal gallium nitride (h-GaN) on a sapphire substrate using photochemical vapor deposition (PCVD) has been demonstrated. A high photoluminescence (PL) peak at 3.47 eV was observed at 5 K, indicating a high-quality crystalline structure for h-GaN. A RT PL energy peak of 3.40 eV indicated the reduction of thermal residual stresses in GaN. In addition, the RT growth resulted in the formation of dendrite-like GaN, which originated from the low kinetic energy of the precursors for migration. A high PL peak at 3.55 eV observed at 5 K in the dendrite-like GaN indicated the quantum size effect.},

keywords = {GaN},

pubstate = {published},

tppubtype = {article}

}

@article{2006kitamuraOptRev,

title = {Near-field evaluation of a quantum size effect in self-aligned GaN whiskers fabricated by photochemical etching},

author = {Kokoro Kitamura and Takashi Yatsui and Motoichi Ohtsu},

doi = {10.1007/s10043-006-0222-3},

year  = {2006},

date = {2006-07-01},

journal = {Optical Review},

volume = {13},

number = {4},

pages = {222-224},

publisher = {Springer Nature},

abstract = {We fabricated nanoscale GaN whiskers using photochemical etching. The fabricated GaN whiskers were conjugated and aligned perpendicular to the incident light polarization used for photochemical etching in a self-assembling manner. Their far-field photoluminescence spectra exhibited a blue-shifted photoluminescence peak at 3.60eV. Near-field photoluminescence spectra of individual GaN whiskers were obtained, for the first time. The evaluation of the near-field spectra identified several peaks from individual whiskers, corresponding to a diameter range of 5-10 nm, and revealed a stepwise change in the diameter along the axis of individual whisker.},

keywords = {GaN, Photochemical etching, Whisker},

pubstate = {published},

tppubtype = {article}

}

@article{doi:10.1063/1.1806271,

title = {Room-temperature synthesis of ultraviolet-emitting nanocrystalline GaN films using photochemical vapor deposition},

author = {Shunsuke Yamazaki and Takashi Yatsui and Motoichi Ohtsu and Taw-Won Kim and Hiroshi Fujioka},

doi = {10.1063/1.1806271},

year  = {2004},

date = {2004-10-01},

journal = {Applied Physics Letters},

volume = {85},

number = {15},

pages = {3059-3061},

abstract = {We fabricated UV-emitting nanocrystalline gallium nitride (GaN) films at room temperature using photochemical vapor deposition (PCVD). For the samples synthesized at room temperature with V/III ratios exceeding 5.0×10^4, strong photoluminescence peaks at 3.365 and 3.310eV, which can be ascribed to transitions in a mixed phase of cubic and hexagonal GaN, were observed at 5K. A UV emission spectrum with a full width at half-maximum of 100meV was observed, even at room temperature. In addition, x-ray photoelectron spectroscopy measurement revealed that the film deposited by PCVD at room temperature was well nitridized.},

keywords = {GaN},

pubstate = {published},

tppubtype = {article}

}