隨著無線通訊的發展，應用於射頻頻段的表面聲波元件往高頻、寬頻寬、高散熱發展，但傳統使用的單晶表面聲波基板材料，其波速低、散熱差、價格昂貴，使其發展受限，近年來，壓電多層膜表面聲波元件得到廣泛的關注及研究，這是因為表面聲波元件可以透過選用不同特性材料組成的多層結構可以顯現各自材料的優勢，不僅提升元件性能、實現電路整合並且能縮小元件尺寸、降低成本，研製出新型元件，拓寬其應用範圍。
類碳鑽/矽基板具有比傳統單晶基板優良的波速且散熱較好，製程相對於鑽石容易，並可與半導體製程整合，而氮化鋁薄膜雖然擁有很高的表面聲波波速、高居禮溫度，但是其機電耦合係數(K2)僅有0.3 %，並不足夠應用在未來無線通訊及物聯網上，故在高C軸取向之wurtzite氮化鋁薄膜內加入鈧之後，由於薄膜結構的轉變，利於誘發極化，使壓電係數增加，即代表K2增加。
因此本研究利用雙靶共鍍的方式濺鍍氮化鈧鋁薄膜於類碳鑽/矽基板上，將探討鈧元素添加不同的含量，對氮化鈧鋁的C軸優選取向之影響及其相變化，不同的薄膜性質將顯著影響薄膜之壓電特性，並找出具最佳壓電係數(d33)的氮化鈧鋁薄膜。結合各材料特點，研製出一創新多層結構壓電材料。
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30.33 % Sc時達到最大值11.54 pC/N，約為純氮化鋁(0.73 pC/N)的15倍之多，主要是因為薄膜結構產生轉變而使壓電性質有所變化，同時由於薄膜結構的改變，造成表面粗糙度的提升。一般而言，C軸取向為控制壓電特性的主因，其結晶性愈好、C軸方向性愈強烈的結構，代表其壓電性質愈優良，具有應用於高頻表面聲波元件的潛力。

We report deposition of pure AlN and ScxAl1-xN thin films with different Sc concentration on DLC/Si substrate by RF and DC reactive magnetron co-sputtering method by using Al and Sc as targets. The X-ray diffraction (XRD) results showed that the films have high c-axis-orientation. Electron probe microanalyzer (EPMA) analysis reveals the presence of scandium atoms reduce the space occupied by aluminum atoms, leading to lattice distortion during the phase transition. The SEM cross-section results showed that the ScxAl1-xN films are highly aligned along c-axis and have columnar like morphology. The top view of SEM results indicated that the new phase formation above Sc 30.33 %, however no new peak appeared in the XRD pattern. The piezoelectric coefficient (d33) of ScxAl1-xN thin films are measured and the highest value (11.54 pC/N) is achieved at x= 30.33 % increasing 14 times, as that with AlN/DLC/Si, 0.73 pC/N. ScxAl1-xN films on DLC/Si substrate have a great potential to be applied on high frequency SAW devices in the future.

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