JOPSS - Search Results

Journal Articles

Size of small Si and Ge clusters on Si(111) and Ge(111) surfaces

Asaoka, Hidehito; Cherepanov, V.*; Voigtlnder, B.*

Surface Science, 588(1-3), p.19 - 25, 2005/08

https://doi.org/10.1016/j.susc.2005.05.022

Times Cited Count：24 Percentile：66.99(Chemistry, Physical)

We determined the average size of small Si and Ge clusters conned to one half of a (77) or (55) unit cell of a Si or Ge(111) surface. The size of Si and Ge clusters conned to a Si(111)-(77) half unit cell was determined to be 8.31 atoms and 7.51 atoms, respectively for a growth temperature of 400 K. This is the same value within the error and shows, that the material of the clusters is less important for the cluster size. On the Ge surface it was found that the reconstruction unit cell is important for the cluster size. On the (55) reconstructed Ge(111) surface the Si clusters have a smaller size of 4.71 atoms compared to 8.21 atoms for Si clusters on the Ge(111)-(77) surface.

Journal Articles

Growth and characterization of thin films on hydrogen layers

Asaoka, Hidehito

KEK Proceedings 2004-5, p.52 - 53, 2004/08

no abstracts in English

Journal Articles

Comparison between surfactant-mediated Bi/Ge/Si(111) epitaxy and Ge/Si(111) epitaxy

Paul, N.*; Asaoka, Hidehito; Voigtlnder, B.*

Surface Science, 564(1-3), p.187 - 200, 2004/08

https://doi.org/10.1016/j.susc.2004.06.194

Times Cited Count：7 Percentile：37.61(Chemistry, Physical)

Using scanning tunneling microscopy (STM) the Ge epitaxy on a Bi terminated Si(111) surface is compared to the growth without surfactant. As soon as the 2 bilayer high wetting layer is completed with surfactant, Ge islands with a flat top and an underlying dislocation network occur. Elastic distortions due to the dislocation network result in periodic sub-Angstrom height undulations measured by the STM. In this case the Ge islands have the form of a mesa. With increasing Ge coverage, these mesas spread laterally. Beyond a Ge coverage of 10 bilayers, the Ge mesas have coalesced and further Ge deposition leads to a 2D layer-by-layer growth of Ge on Si(111). In epitaxy without the use of a surfactant as well, the formation of Ge islands with an underlying dislocation network is observed. However, in this case the Ge islands are much higher and show no tendency to coalesce. The partially relaxed islands coexist with another type of tall islands.

Journal Articles

Growth mechanisms in Ge/Si(111) heteroepitaxy with and without Bi as a surfactant

Paul, N.*; Asaoka, Hidehito; Mysliveek, J.*; Voigtlnder, B.*

Physical Review B, 69(19), p.193402_1 - 193402_4, 2004/05

A2003-0489.pdf:0.64MB

https://doi.org/10.1103/PhysRevB.69.193402

Times Cited Count：21 Percentile：67.06(Materials Science, Multidisciplinary)

We compare the initial stages of growth of Ge on Si(111) with Bi as a surfactant and without surfactant. At the beginning of growth, 3D islands with a strain relieving dislocation network at their base are formed in both growth systems. These islands can be regarded as seeds of a flat relaxed Ge layer on Si(111). However, such Ge layer forms at later stages of growth only in the growth with Bi surfactant, while the growing Ge layer without surfactant remains rough. What makes the dierence and the success of Bi surfactant mediated epitaxy is the lateral growth and coalescence of the seed islands that cover the entire surface within first 15 bilayers of Ge deposition. This happens due to a kinetic limitation of the incorporation of Ge into the growing layer in the presence of surfactant.

Journal Articles

Optical spectroscopy of plasma plume induced by pulsed laser deposition of TiO $_{2}$ thin films

Kitazawa, Shinichi; Yamamoto, Shunya

Transactions of the Materials Research Society of Japan, 28(4), p.1133 - 1136, 2003/12

The epitaxial growth of high quality TiO $_{2}$ films has attracted much interest from the viewpoints of basic science and applications. In the synthesis process of TiO $_{2}$ films, the pulsed laser deposition (PLD) method is widely employed because of its advantage for materials with high melting point. The laser irradiation generates plasmas from Ti bulk targets, and the evaporated Ti particles have interactions with buffer dioxide gas before/after the epitaxial growth. We observed the optical emission spectra from the plumes generated by laser ablation in order to improve on the epitaxial growth under proper conditions. The spectra show dependences of energy densities and wavelengths of the laser. The spectra are investigated for relevancies to the quality of films and crystallographic relationships that were assessed by x-ray diffraction, x-ray pole figures and Rutherford backscattering spectroscopy.

Journal Articles

Real-time stress/strain measurement during growth of Sr and SrO epilayer on H-terminated Si

Asaoka, Hidehito; Machida, Yusuto; Yamamoto, Hiroyuki; Hojo, Kiichi; Saiki, Koichiro*; Koma, Atsushi*

Thin Solid Films, 433(1-2), p.140 - 143, 2003/06

https://doi.org/10.1016/S0040-6090(03)00305-5

Times Cited Count：2 Percentile：15.13(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Stress evolution during epitaxial growth of SrO films on hydrogen-terminated Si(111) surfaces

Asaoka, Hidehito; Machida, Yusuto; Yamamoto, Hiroyuki; Hojo, Kiichi; Saiki, Koichiro*; Koma, Atsushi*

Solid State Communications, 124(7), p.239 - 242, 2002/11

https://doi.org/10.1016/S0038-1098(02)00579-3

Times Cited Count：7 Percentile：38.72(Physics, Condensed Matter)

no abstracts in English

Journal Articles

RBS/channeling analysis of epitaxial films with Nb buffer layer on sapphire substrate

Yamamoto, Shunya; Naramoto, Hiroshi

Nuclear Instruments and Methods in Physics Research B, 190(1), p.657 - 660, 2002/00

https://doi.org/10.1016/S0168-583X(01)01269-1

Times Cited Count：2 Percentile：18.91(Instruments & Instrumentation)

Epitaxial Cu (111), Al (111) and Sc (0001) films were successfully grown on -Al $_{2}$ O $_{3}$ (110) substrates with a high quality Nb (110) buffer layer by electron beam evaporation technique. Films were analyzed by RBS/channeling and X-ray diffraction techniques. The Cu (111) film and Al (111) film on the Nb (110) buffer layer have twinned structure, which is rotated by 180 $^{circ}$ with each other around the 111 direction. The crystal quality of Cu (111) layer was improved with the increase of Nb (110) buffer layer thickness and then saturates at the high quality after about 2 nm thickness.

Journal Articles

Preparation of epitaxial TiO $_{2}$ films by pulsed laser deposition technique

Yamamoto, Shunya; Sumita, Taishi; Sugiharuto; Miyashita, Atsumi; Naramoto, Hiroshi

Thin Solid Films, 401(1-2), p.88 - 93, 2001/12

https://doi.org/10.1016/S0040-6090(01)01636-4

Times Cited Count：129 Percentile：96.8(Materials Science, Multidisciplinary)

The epitaxial growth of high-quality TiO $_{2}$ films has attracted much interest from the viewpoints of basic science and applications. In this study, it is shown that TiO $_{2}$ films with anatase and rutile structure can be prepared by pulsed laser deposition (PLD) with a Nd-YAG laser under the controlled O $_{2}$ atmosphere. The TiO $_{2}$ films with 200 nm thickness were prepared on the SrTiO $_{3}$ , LaAlO $_{3}$ , LSAT and -Al $_{2}$ O $_{3}$ single crystal substrates. The epitaxial films were analyzed by Rutherford backscattering spectrometry (RBS) combined with channeling and X-ray diffraction for the crystallographic relationships with the substrates. The high quality anatase TiO $_{2}$ (001) films have been successfully prepared on the LaAlO $_{3}$ (001), LSAT (001) and SrTiO $_{3}$ (001) substrates about 500 $^{circ}$ C substrate temperature. Also the high quality rutile TiO $_{2}$ (100) and TiO $_{2}$ (001) films were obtained on the -Al $_{2}$ O $_{3}$ (0001) and (100), respectively.