Optical properties of nanostructured (Ga,Ge) chalcogenides.
| Project/Area Number |
14540292
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | University of Tsukuba |
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Principal Investigator |
ONARI Seinosuke University of Tsukuba, Graduate School of Pure and Applied Sciences, Professor, 大学院・数理物質科学研究科, 教授 (70015824)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUISHI Kiyoto University of Tsukuba, Graduate School of Pure and Applied Sciences, Asociate Professor, 大学院・数理物質科学研究科, 助教授 (10202318)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2004: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2003: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2002: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Keywords | nano structure / chalcogenide semiconductors / GaSe / optical properties / Laser ablation in gas / Raman scattering / optical absorption / photo-luminescence / GaSe(セレン化ガリウム) / ガス中レーザアブレーション法 / 蛍光測定 / ガス中レーザァブレーション法 |
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| Research Abstract |
Nano structured layer compounds GaSe are fabricated by Laser ablation method, and optical properties are measured.
Size distribution of GaSe nano particles are shown to depend on the ambient gas pressure. Direct and indirect deposition effects are shown to depend strongly on the strength of laser light at the ablation process.
From the absorption spectra of GaSe nano particles, quantum confinement effects due to the size effect are observed. From the PL measurement, emission from surface level or defect level are observed.
Shifts of the HOMO-LUMO transition energy due to the quantum size effect are calculated by the effective mass approximation taking into 3D confinement. Using 2D confined effective mass approximation, energy gap of GaSe is shown to depend strongly on the confinement in the direction of layers.
From the Raman and infrared measurements, confined phonon modes of GaSe are studied on samples produced under various ambient gas pressure and gas species. Disappearance of 233cm^<-1> line is observed, and it is interpreted by the shielding effect of dipoles inside nano particles. New phonon modes at 55cm^<-1> and 230cm^<-1> are observed on nano particles and the possibility of surface phonon modes are discussed.
Interlayer stretching modes are analyzed by Champbell-Fauchet model. Low frequency shifts of A'1(2) modes are suggested by the calculation with force constant model to originate from the disturbance in the Ga-Ga bonds and in the vibration in the intra-layer vibration modes.
Finally dimensionality of phonon confinement effects are studied taking into consideration the 2D and 3D phonon confinement effects.
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Report
(4 results)
Research Products
(22 results)
