Papers - Watanabe, Shinichi

Transformation of GaAs (001)-(111)B facet structure by surface diffusion during molecular beam epitaxy

S. Koshiba, Y. Nakamura, T. Noda, S. Watanabe, H. Akiyama, and H. Sakaki

Journal of Crystal Growth 227-228   62-66 2001.07

Research paper (scientific journal), Joint Work, Accepted

Transformation of GaAs (001)-(111)B facet structure by surface diffusion during molecular beam epitaxy on patterned substrates

S Koshiba, Y Nakamura, T Noda, S Watanabe, H Akiyama, H Sakaki

JOURNAL OF CRYSTAL GROWTH (ELSEVIER SCIENCE BV)  227   62 - 66 2001.07

Accepted,  ISSN  0022-0248

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The mechanisms of molecular beam epitaxy growth on the mesa patterned substrates which results in the formation of sharp ridge structure were investigated. A simple model, based oil the scanning electron microscope measurements, nicely explains the time dependent growth rates as well as the change of the facet shape during the formation of ridge structure originating from the strong Ga atoms migration. The estimated number of atoms crossing the boundary changes according to the alternating facet shape and this indicates the instability in the facet growth. As a result, the mechanism of mesa growth was clarified, which becomes self-regulatory while the facet shape and/or the boundary condition vary as the growth progresses. (C) 2001 Elsevier Science B.V. All rights reserved.

Microscopy of electronic states contributing to lasing in ridge quantum-wire laser structure

S. Watanabe, S. Koshiba, M. Yoshita, H. Sakaki, B. Motoyoshi, and H. Akiyama

Applied Physics Letters (AMER INST PHYSICS)  75 ( 15 ) 2190-2192 - 2192 1999.10

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0003-6951

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Distribution of electronic states inside ridge quantum-wire (QWR) laser cavity was investigated using spatially and spectrally resolved top-view photoluminescence (PL) imaging method. PL inhomogeneity in QWR has shown that the electronic states were perturbed by the fluctuation of vertical thickness in the scale of similar to nm, while the optical waveguide was not. The PL images of QWR were traced up to the lasing condition to examine the lasing origin. (C) 1999 American Institute of Physics. [S0003-6951(99)00541-0].

Selective molecular beam epitaxy (MBE) growth of GaAs AlAs ridge structures containing 10 nm scale wires and side quantum wells (QWs) and their stimulated emission characteristics

S. Koshiba, S. Watanabe, Y. Nakamura, M. Yamauchi, M. Yoshita, M. Baba, H. Akiyama, and H. Sakaki

Journal of Crystal Growth (ELSEVIER SCIENCE BV)  201-202   810-813 - 813 1999.05

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0022-0248

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We report on the formation and optical characteristics of ridge waveguide structures containing quantum wires (QWRs). To form a waveguide? we adopted digital alloys, i.e. short-period superlattices (SLs), rapid changes of As fluxes using valved cells, growth temperatures (T-s), and introduction of growth interruptions. Stimulated emission from these ridge QWR laser structures was observed at temperatures 4.7-290 K by optical pumping. (C) 1999 Elsevier Science B.V. All rights reserved.

Stimulated emission in ridge quantum wire laser structures measured with optical pumping and microscopic imaging methods

S. Watanabe, S. Koshiba, M. Yoshita, H. Sakaki, B. Motoyoshi, and H. Akiyama

Applied Physics Letters (AMER INST PHYSICS)  73 ( 4 ) 511-513 - 513 1998.05

Research paper (scientific journal), Joint Work, Accepted,  ISSN  0003-6951

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We report the observation of stimulated emission in ridge quantum wire (QWR) structures at temperatures from 4.7 to 290 K. To examine the origin of the stimulated emission, the spatially and spectrally resolved microscopic images of the emission were measured. It was most likely attributed to the optical transition between the excited states in QWRs. (C) 1998 American Institute of Physics.