本研究討論五氧化二鉭/砷化鎵薄膜系統之奈米壓痕行為，以及退火前後機械性質、表面形貌和微觀結構之變化。本實驗利用射頻濺鍍機於砷化鎵基板上沉積 200nm 及 300nm 之五氧化二鉭薄膜，並對退火組試片施以450°C持溫20 分鐘之熱處理。且在奈米壓痕試驗中，對薄膜厚度200nm 試片進行150nm 和350nm 深度之試驗，並對薄膜厚度300nm 試片進行250nm 和450nm 深度之試驗，以了解退火前後、壓痕深度與膜厚之影響。
實驗結果顯示，退火前之負載-深度曲線在壓痕深度超過薄膜厚度會有pop-in 之現象，但經退火後硬度及楊氏模數皆略微下降，且薄膜脫落基板的情狀較不明顯，並無發生 pop-in 之現象。同時，不論退火與否，在壓痕深度壓入基板前，薄膜越厚，硬度值越高。壓痕深度壓入基板後，薄膜越厚，硬度值越低；楊氏模數則不論在壓痕深度壓入基板前後，薄膜越厚，楊氏模數越低。在試片表面形貌與剖面微觀結構，呈現壓痕深度越深，表面變形量與差排數量也越多。而退火後表面變形較無太大差異，但當壓痕深度在薄膜厚度前50nm 處，因薄膜與基板結合力較強，使外力較平均傳遞到基板，差排數量提升。而當壓痕深度在薄膜厚度後150nm 處，差排數量則無太大的差異。

The mechanical properties of Ta2O5/GaAs thin film with and without annealing were performed at room temperature using nanoindentation test. Indentation at depths of 150, 350 nm and 250, 450 nm for specimens with Ta2O5 film thicknesses of 200 nm and 300 nm, respectively. In the annealed specimens, annealed at a temperature of 450°C for 20 minutes. The results show that without annealing the pop-in effect appeared at the load-displacement curve after the indenter reached the substrate, which is due to the delamination of the thin film from the substrate. After annealing, the load-displacement curve becomes smooth and the hardness and Young’s modulus were found to decrease. Furthermore, the changes of the microstructure show that the residual deformation is slightly smaller, there are no cracks at the tips of all indentation triangles, and there is little difference in dislocation density. Regardless of whether the specimens are annealed or not, the film thickness increased with increasing hardness before the indenter reached the substrate, and the film thickness increased with decreased hardness after the indenter reached the substrate. Furthermore, the film thickness increased with decreased Young's modulus regardless of whether the specimen is annealed or at different depths.

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