| Summary: | 碩士 === 明道大學 === 材料科學與工程學系碩士班 === 99 === Radio-frequency (RF) Parallel plate reactors are commonly used for plasma-enhanced chemical vapor deposition (PECVD) of hydrogenated amorphous silicon (a-Si:H) thin films. Non-intrusive plasma diagnostics for industrial RF parallel-plate reactors can be useful for process optimization and monitoring, provided that their implementation is practical. In this study, the a-Si:H thin films have been deposited in a parallel-plate 27.1 MHz radio frequency (RF) plasma reactor fed with hydrogen and pure SiH4. The plasma characterization has been performed by optical emission spectrometry (OES) for the analysis of the emitting species SiH*(414nm) and H* (656 nm、722 nm 、772 nm) . The main features of the spectra correspond to the emission of SiH* and H* excited radicals, which directly come from dissociative excitation by electron collision processes with SiH4. The effect of the RF power (10-30 W) , the hydrogen flow from 120 sccm to 200 sccm, the electrode distance from 20 mm to 40 mm on the plasma phase composition and on the film growth rate has been investigated. The results showed the deposition rate, hydrogen content, and microstructural defect factor (R) of the a-Si:H films correlated with SiH* and H* radical intensities. The statistical film uniformity and efficiency of the a-Si:H thin film solar cells were also studied. It revealed a chemisorptions-based deposition model of the growth mechanism. Finally, the a-Si:H thin film solar cell with efficiency of 9.1 % have been obtained.
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