成果報告書詳細
管理番号20130000000750
タイトル*平成24年度中間年報 ナノテク・先端部材実用化研究開発 非鉛圧電材料によるマイクロ振動発電デバイスの研究開発
公開日2013/10/1
報告書年度2012 - 2012
委託先名国立大学法人東北大学 株式会社メムス・コア
プロジェクト番号P05023
部署名電子・材料・ナノテクノロジー部
和文要約
英文要約We have investigated a lead-free AlN thin film as an environmental friendly piezoelectric material for the vibration-based micro energy harvester which can convert vibration energy around us to electrical energy.
To obtain as much energy as possible by vibrating a piezoelectric AlN thin film, we have studied the piezoelectric characteristics of AlN thin films with specific crystallographic direction and to fabricate AlN thin films with specific crystallographic orientation to clarify an AlN thin film with high c-axis orientation. Theoretical study of dependence of piezoelectric strain and stress coefficients (d31 and e31, respectively) and electromechanical coupling factor (k31) as a function of crystallographic direction from the c-axis were conducted. AlN thin films were deposited using electron cyclotron resonance (ECR) sputtering with changing angle between surface of the substrates and AlN flux, and evaluated by X-ray diffraction (XRD) measurement. XRD patterns suggested the possibility that crystallographic orientation of the AlN thin films changed due to deposition angle. We also succeeded to optimize fabrication conditions to obtain the best interface between the AlN thin film and SUS substrate with minimum internal stress by carefully analyzing our experimental data.
The output power of the energy harvester as a function of vibration frequency was investigated by applying acceleration of 0.2-3.0 g. We have shown that our AlN energy harvester using SUS substrate successfully generated the output energy of about 90 μW at 1.6 g, which is a targeted value of this study.
Along with development of vibration-based energy harvester, this study intends to realize high-vacuum packaging with low-threshold diodes and micro electric double layer capacitors for higher DC output power and long life. For this purpose, first, we have developed an energy harvesting device prototype packaged by high-vacuum packaging ceramics. Also, we examined surface treatment of Si, and demonstrated a new wet process which can efficiently fabricate nano-porus Si surface to expand surface area of Si. It is shown that the combination of the low threshold voltage of the InP/In2O3 hetero-junction diode and the nano silicon capacitor realizes high electric charge capacity.
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