| 사파이어 기판방향에 따른 GaN 박막의 표면탄성파 특성에 대한 이론적 계산 |
| 임근환, 김영진, 최국현1, 김범석1, 김형준1, 김수길2, 신영화2 |
경기대학교 재료공학과
1서울대학교 재료공학부
2경원대학교 전자공학과 |
| Theoretical Calculation of SAW Propagation of GaN/Sapphire Structure according to SAW Propagation Direction |
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| ABSTRACT |
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The GaN/sapphire layered structure is a potential candidate for high frequency devices due to high acoustic velocity of sapphire. Generally, the GaN thin films are epitaxially grown on c, a, and r-plane sapphire substrates. In this study, wave equations of GaN/sapphire structure were calculated according to crystallographic relationship between GaN layer and sapphire substrate. On each plane, the shear velocity was changed by the kH of GaN layer and propagation direction on sapphire substrate. We found electromechanical coupling constant of r-plane was better than the others. As a result, elastic stiffness and electromechanical coupling constant of materials are affected by a cut and an orientation of substrate. GaN/r-plane sapphire structure is more advantageous for high frequency SAW devices. |
| Key words:
GaN, Sapphire, Shear velocity, SAW, Piezoelectrics, Electromechanical coupling constant ($K^2$) |
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