1 0 0 0 OA Epitaxial growth of ferromagnetic CoxFe4−xN thin films on SrTiO3 (001) and magneticproperties
- 著者
- Sanai Tatsunori Ito Keita Toko Kaoru Suemasu Takashi
- 出版者
- Elsevier B.V.
- 雑誌
- Journal of crystal growth (ISSN:00220248)
- 巻号頁・発行日
- vol.378, pp.342-346, 2013-09
- 被引用文献数
- 5 1
We formed CoxFe4−xN (0≤x≤2.9) epitaxial thin films on SrTiO3 (001) substrates by molecular beam epitaxy supplying solid Co and Fe and a radio frequency N2 plasma, simultaneously. The composition ratio of Co/Fe in CoxFe4−xN was controlled by changing the weight ratio of Co to Fe flakes in the crucible of the Knudsen cell used. Epitaxial growth of CoxFe4−xN thin films were confirmed by reflection high-energy electron diffraction and θ–2θ X-ray diffraction patterns. Magnetization versus magnetic field curves measured at room temperature using a vibrating sample magnetometer showed that the axis of easy magnetization was changed from [100] to [110] with increasing x in CoxFe4−xN.
1 0 0 0 OA Formation of large-grain-sized BaSi2 epitaxial layers grown on Si(111) by molecular beam epitaxy
- 著者
- Baba M. Toh K. Toko K. Hara K.O. Usami N. Saito N. Yoshizawa N. Suemasu T.
- 出版者
- Elsevier B.V.
- 雑誌
- Journal of crystal growth (ISSN:00220248)
- 巻号頁・発行日
- vol.378, pp.193-197, 2013-09
- 被引用文献数
- 5 1
BaSi2 epitaxial films were grown on Si(111) substrates by a two-step growth method including reactive deposition epitaxy (RDE) and molecular beam epitaxy (MBE). To enlarge the grain size of BaSi2, the Ba deposition rate and duration were varied from 0.25 to 1.0 nm/min and from 5 to 120 min during RDE, respectively. The effect of post-annealing was also investigated at 760 °C for 10 min. Plan-view transmission electron micrographs indicated that the grain size in the MBE-grown BaSi2 was significantly increased up to approximately 4.0 μm, which is much larger than 0.2 μm, reported previously.
- 著者
- Khan M. Ajmal Hara Kosuke O. Nakamura Kotaro Du Weijie Baba Masakazu Toh Katsuaki Suzuno Mitsushi Toko Kaoru Usami Noritaka Suemasu Takashi
- 出版者
- Elsevier B.V.
- 雑誌
- Journal of crystal growth (ISSN:00220248)
- 巻号頁・発行日
- vol.378, pp.201-204, 2013-09
- 被引用文献数
- 18 1
We have successfully grown a-axis-oriented p-type BaSi2 films on Si(111) by in situ boron (B) doping using molecular beam epitaxy (MBE). The hole concentration in B-doped BaSi2 was controlled in the range between 1017 and 1019 cm−3 at room temperature by changing the temperature of the B Knudsen cell crucible. The acceptor level was estimated to be approximately 23 meV.
- 著者
- Nakamura K. Toh K. Baba M. Khan M. Ajmal Du W. Toko K. Suemasu T.
- 出版者
- Elsevier B.V.
- 雑誌
- Journal of crystal growth (ISSN:00220248)
- 巻号頁・発行日
- vol.378, pp.189-192, 2013-09
- 被引用文献数
- 9 4
Al or B layers of a few hundreds of nm in thickness deposited on BaSi2 epitaxial films on Si(1 1 1) substrates were annealed at different temperatures, and the diffusion coefficients of Al and B were evaluated using secondary ion mass spectrometry with O2+. We also investigated the effect of post annealing (850 °C, 10 min) of BaSi2 films on the diffusion coefficients. It was found that both the lattice diffusion and the grain boundary diffusion were decreased by the post-annealing. The plan-view transmission electron microscopy images revealed that the grain size was increased from approximately 0.2 to 0.6 μm by the annealing, and the X-ray diffraction intensities also increased. The activation energies of lattice and grain boundary diffusions in the post-annealed BaSi2 are 0.63 eV and 0.58 eV for Al, and 4.6 eV and 4.4 eV for B, respectively.
1 0 0 0 OA Temperature dependent Al-induced crystallization of amorphous Ge thin films on SiO2 substrates
- 著者
- Toko Kaoru Fukata Naoki Nakazawa Koki Kurosawa Masashi Usami Noritaka Miyao Masanobu Suemasu Takashi
- 出版者
- Elsevier B.V.
- 雑誌
- Journal of crystal growth (ISSN:00220248)
- 巻号頁・発行日
- vol.372, pp.189-192, 2013-06
- 被引用文献数
- 15 4
High-quality crystalline Ge thin films on low-cost glass substrates are desired to reduce the fabrication cost of high-efficiency tandem solar cells. We applied an Al-induced crystallization technique to amorphous-Ge films (50-nm thickness) on SiO2 glass substrates. The annealing temperature of the sample strongly influenced the grain size and the crystal orientation in the grown polycrystalline Ge layers: low annealing temperatures resulted in large grains and high (111)-orientation fractions. As a result, annealing at 325 °C provided 98% (111)-oriented grains with average diameters of 30 μm. Moreover, the grown Ge layers could be used as an epitaxial template for chemical vapor deposition. This large-grained Ge film on a SiO2 substrate appears promising for use as a Ge light-absorbing layer, as well as an epitaxial buffer layer for group III–V compound semiconductors.
- 著者
- Sanai Tatsunori Ito Keita Toko Kaoru Suemasu Takashi
- 出版者
- Elsevier B.V.
- 雑誌
- Journal of crystal growth (ISSN:00220248)
- 巻号頁・発行日
- vol.357, pp.53-57, 2012-10
- 被引用文献数
- 13
We attempted to grow CoxFe4−xN epitaxial thin films on SrTiO3(001) substrates by molecular beam epitaxy supplying solid Co and Fe and a radio frequency N2 plasma, simultaneously. The composition ratio of Co/Fe in CoxFe4−xN was controlled by changing the weight ratio of Co to Fe flakes in the crucible of the Knudsen cell used. We confirmed epitaxial growth of CoxFe4−xN (0.4<x<2.9) thin films by reflection high-energy electron diffraction and θ−2θ X-ray diffraction patterns. The in-plane lattice parameter of the CoxFe4−xN films was almost the same as the out-of-plane lattice parameter, and they decreased with increasing Co composition, following Vegard's law.
- 著者
- Okada Atsushi Toko Kaoru O. Hara Kosuke Usami Noritaka Suemasu Takashi
- 出版者
- Elsevier B.V.
- 雑誌
- Journal of crystal growth (ISSN:00220248)
- 巻号頁・発行日
- vol.356, pp.65-69, 2012-10
- 被引用文献数
- 20
We have fabricated poly-Si thin films on fused silica substrates by the Al-induced crystallization (AIC) method with SiO2 insertion layers of various thicknesses (0–20 nm). The growth morphologies of poly-Si layers were dramatically changed by the SiO2 thickness, i.e., thin layers (2 nm) provided high growth rates and (100) orientations, and thick layers (10 nm) provided low growth rates and (111) orientations. These results showed that the crystal orientation of AIC-Si significantly depends on the diffusion rate of Si atoms into the Al layer.