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CSME 2021/12
Volume 42 No.6
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539-550
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Nanoindentation Behaviour of As-Deposited and Annealed SiO2/GaAs Thin Films
Woei-Shyan Leea and Wilbert Chua
aDepartment of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan 70101, ROC.
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Abstract:
SiO2 thin films with thicknesses of 200 nm and 300 nm, respectively, are deposited on GaAs substrates. The mechanical properties of the SiO2/GaAs thin-film systems are evaluated under room temperature (RT) conditions by nanoidentationtests performed to depths ranging from 150 to 350 nm. The tests are performed using both as-deposited samples and samples annealed at 500 ℃ for 30 minutes. The results show that for the as-deposited specimens, a pop-in effect occurs in the loading curve for all film thicknesses and nanoindentation depths (150 nm and 350 nm) due to delamination of the thin film from the substrate. However, for the annealed samples, no pop-in events are observed, irrespective of the film thickness or nanoindentation depth. For both samples (as-deposited and annealed), the maximum indentation load increases with an increasing indentation depth and film thickness. However, the shape of the hardness-depth curve for the annealed specimens is different from that of the as-depositedspecimens. Moreover, the hardness of the annealed specimens is slightly less than that of the as-deposited specimens at the maximum indentation depth. Similar tendencies can be observed for the variation ofYoung’s modulus with the indentation depth.Scanning electron microscopy (SEM) observations show that the indentation area increases with an increasing indentation depth and thin film thickness, but decreases in the annealed condition. The transmission electron microscopy (TEM) observations reveal that no delamination occurs for the annealed specimen with the maximum thickness of 300 nm under indentation depths of 150 nm and 350 nm.
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Keywords: Nanoindentation, GaAs, Microstructural evolution, Annealing, SiO2 Thin films
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©
2021
CSME , ISSN 0257-9731
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