以過渡金屬二硫化物為緩衝層材料濺鍍沈積氮化鎵薄膜之研究

Fabrication study of sputtered GaN films using Transition Metal Dichalcogenides as buffer layer

莊詠勛(YUNG-HSUN CHUANG)

指導教授 ： 高慧玲

中原大學/電機資訊學院/電子工程學系/碩士(2023年)

https://doi.org/10.6840/cycu202301030

摘要

本研究透過迴旋濺鍍法，以砷化鎵為靶材，沉積氮化鎵薄膜在Sapphire、WS2/Sapphire及MoS2/Sapphire三種基板上，探討過渡金屬二硫化物緩衝層及製程條件對氮化鎵薄膜的影響。
先是透過TEM的EDS確認在750°C時，沒有從砷化鎵靶材來的砷殘餘在薄膜內。本實驗為了解決過去成長速率太快造成薄膜差排過多的問題，降低了Target功率及通入不同氮氣濃度。於是再以SEM來確認各參數下的薄膜厚度，以及成長速率，並與過去結果做比較，發現成長速率有明顯的下降，從過去的1.6 (Å/s) 下降了2-4倍左右。再透過XRD量測在相同靶材功率下，做氮氣濃度對薄膜品質的影響，可得知隨著氮氣濃度的上升，並不會使氮化鎵的薄膜品質變好。再透過XRD量測在同樣氮氣濃度為50%，分別在50 W、75 W及100 W的製程參數，做靶材功率對薄膜品質的影響，看出50 W的薄膜品質有較好的結果。再透過TEM的選區繞射圖中，發現了局部單晶的現象，也證實以WS2作為緩衝層確實可以改善晶格排列情形，來提升薄膜品質。最後拿過去在50%氮氣，Target功率為150 W的結果與本次實驗的50 W，發現差排明顯變少了，且晶格排列的更整齊了。

關鍵字

氮化鎵薄膜 ； 濺鍍 ； 過渡金屬二硫化物(TMDc) ； 砷化鎵靶材

並列摘要

In this thesis, GaN thin films were deposited on sapphire substrates with and without Transition metal dichalcogenide buffer layers (mainly WS2 and MoS2) using helicon sputtering system. The effects of the buffer layers as well as the growth conditions on the crystallinity of GaN films were investigated and discussed.
It was first been confirmed there is no arsenic from the GaAs target remaining in the films as measured by EDS in TEM. In this study, in order to solve the problem of too much dislocation of the films caused by the fast growth rate in the past, the cathode power was reduced and various nitrogen concentrations were employed. It was found that the growth rate measured by SEM decreased significantly from the previous study of 1.6 (Å/s). XRD was used to examine the effect of nitrogen concentration on film quality under the same power. It was found that the increase of nitrogen concentration makes no obvious effect on the GaN film quality. From the XRD results, at the same nitrogen concentration of 50%, the process parameters of 50 W, 75 W, and 100 W were used to examine the influence of target power on film quality. It showed that the film quality of 50 W exhibits superior results. Through the selected area diffraction diagram of TEM, epitaxial single crystals pattern was found on the GaN films prepared on sapphire with WS2 buffer layer. It indeed demonstrated that the addition of TMDCs layer on substrates during the sputtering deposition can improve the GaN film crystallinity.

並列關鍵字

GaN thin film ； sputtering ； Transition Metal Dichalcogenides(TMDc) ； GaAs target

參考文獻

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