Wurtzite結構氮化鋁薄膜之結晶性與壓電性質已被廣泛討論及發表，其優點為居禮溫度極高，可在超過1000oC下操作仍保有壓電性，但缺點為壓電係數過低。在氮化鋁薄膜內摻雜鈧後，由於結晶結構改變，利於誘發極化，使得壓電係數增加。
本實驗利用雙靶共鍍的方式濺鍍氮化鈧鋁薄膜於鑽石基板上，找出具最佳C軸取向的製程參數，以有效提升壓電係數值。而鑽石基板波速高(12000m/s)且散熱性佳，在其表面鍍上一層壓電薄膜後適合應用在高頻表面聲波元件。實驗結果顯示，隨著鈧含量增加，氮化鈧鋁薄膜的d33值會增加，至12 at.% Sc時達到一最大值6.55 pC/N，是純氮化鋁的四倍，這是因為合金薄膜達到一固溶限，並產生相轉變造成壓電性質產生變化。
一般而言，C軸取向結晶性愈好的結構，其壓電性質愈好。快速升溫退火可達到使晶粒成長、消除缺陷以有效改善薄膜結晶性，進而提升薄膜的壓電性質。本實驗做了一系列試驗，發現退火溫度、通入氮氣流量均會影響薄膜的C軸取向結晶性。研究結果顯示，在真空條件下退火，可在較低退火溫度下得到高壓電係數值24 pC/N。
從本實驗可歸納出較低溫的製程參數達到有效提升氮化鈧鋁鑽石薄膜之壓電性質。

Wurtzite Aluminum Nitride thin films have been widely studied and published recently. Because Aluminum Nitride has the highest Curie temperature, it can be used above 1000oC with its piezoelectricity. But, the piezoelectric coefficient d33 of AlN is too low. In this research, we demonstrated the viability of oriented AlN layer doped with Scandium to enhance its piezoelectricity. Wurtzite (Sc, Al) N thin films were deposited on a diamond structure by a co-sputtering system. The results show that the piezoelectricity was strongly depended on the c-axis orientation of samples. Besides, the piezoelectric coefficient would be enhanced obviously after doping Scandium element into thin films. The d33 value increased with increasing Scandium concentration up to the solution limit of Scandium in Aluminum. We found that the maximum of piezoelectric coefficient of (Sc, Al)N thin film is 6.55 pC/N at 12 at.% Sc, about four times larger than pure AlN layer.
Because the piezoelectric coefficient is strongly related to the c-axis of AlN, the preferred orientation of the thin films needs to be enhanced. Since the crystal quality of thin films could be improved by annealing, rapid thermal annealing process was taken to improve the crystallinity in our experiment. The experimental results show that both annealing temperature and the pressure of nitrogen affect the crystallinity of (Sc, Al)N thin films.
From our research, we conclude a preliminary low-temperature experimental process to enhance the piezoelectricity of (Sc, Al)N thin film up to 24 pC/N effectively, which could be expected to boost the properties of surface acoustic wave filter devices.

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