| Project/Area Number |
12450119
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Electronic materials/Electric materials
|
|---|
| Research Institution | Tohoku University |
|---|
Principal Investigator |
KUSHIBIKI Jun-ichi Tohoku University,Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (50108578)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
MATSUMOTO Yasushi Tohoku University,Research Institute of Electrical Communication, Associate Professor, 電気通信研究所, 助教授 (20312598)
IZUMI Takanaga Tohoku University,Graduate School of Engineering, Research Associate, 大学院・工学研究科, 助手 (30323059)
ARAKAWA Mototaka Tohoku University,Graduate School of Engineering, Research Associate, 大学院・工学研究科, 助手 (00333865)
ODAGAWA Hiroyuki Tohoku University,Research Institute of Electrical Communication, Research Assiciate, 電気通信研究所, 助手 (00250845)
CHO Yasuo Tohoku University,Research Institute of Electrical Communication, Professor, 電気通信研究所, 教授 (40179966)
|
|---|
| Project Period (FY) |
2000 – 2002
|
| Keywords | Ultrasonic microspectroscopy / LFB ultrasonic material characterization / Standard specimen / Damaged surface layer / Leaky surface acoustic wave / Evaluation of single crystal materials / Materials for SAW devices / Scanning nonlinear dielectric microscopy |
|---|
| Research Abstract |
In this study, ultrasonic microspectroscopy (UMS) technology, using the line-focus-beam (LFB) and plane-wave ultrasonic material characterization system, has been applied to the problems associated with the homogeneities and modified/damaged surface layers of LiNbO_3 and LiTaO_3 single crystals for super-high-frequency (SHF) surface acoustic wave (SAW) devices. The purpose of this study was to establish the quantitative analysis and evaluation method using this technology.
1. The relative and absolute accuracies for the propagation characteristics of leaky SAW (LSAW) measured by the LFB-UMC system have been improved.
2. Chemical composition dependences of the acoustical physical constants of LiNbO_3 and LiTaO_3 single crystals were determined. This enables us to calculate the propagation characteristics of LSAW and SAW for the crystals with an arbitrary chemical composition.
3. Experimental relationships (calibration lines) among the LSAW velocity, Curie temperature, lattice constants, et
… More
c., were obtained to evaluate each property of the crystals by a common scale of LSAW velocity.
4. A method for improving the crystal growth conditions through the evaluation of the chemical composition distributions of commercially available LiTaO_3 single crystals was proposed and an extremely homogeneous crystal was successfully grown.
5. For the demonstration of evaluating modified/damaged surface layers, we fabricated several LiTaO_3 substrates with protonexchanged layers and domain-inverted layers as model specimens. The thickness resolution of the surface layers estimated by LSAW velocity was nanometer order.
6. The resolution of scanning nonlinear dielectric microscopy was improved with an atomic size.
7. Center frequencies and SAW velocities were measured for 0.5, 1, and 2 GHz-band SAW filters fabricated on LiTaO_3 wafers whose distributions in chemical composition were preexamined by measuring LSAW velocities. The results exhibited that variations of the center frequencies and differences between the calculated and measured SAW velocities became larger as the frequency became higher. It was considered that problems associated with the damaged surface layers of the substrates were detected. Less
|
