| Summary: | 碩士 === 國立中興大學 === 材料科學與工程學系所 === 101 === Compared with sputtering technique for the growth of boron doped zine oxide (ZnO:B) thin films, metal organic chemical vapor deposition( MOCVD) can directly create textured morphology with excellent light scattering for front electrode application in tandem solar cells. It is also easy to control coating composition and crystal quality, revealing many advantages such as coating on complex shaped substrate with dense structure and good adhesion. For large-scale commercialized production, it is one of the preferred deposition techniques, too.
In this study, diethylzinc (DEZ) and water (H2O) vapor controlled at 4000 sccm / 38℃ and 4500 sccm / 33℃ respectively, were used as precursors and directly evaporated with 4000 sccm argon for dillution. The diborane (B2H6) used as dopant was transported at 850 sccm directly with 4000 sccm argon to the chamber, for 300, 425, 528 and 621s to obtain 4 kinds of film thickness. 3 flow rates of B2H6 including 650 sccm, 750 sccm and 850 sccm conducted to obtain 3 concentrations of B. During the growth, the total pressure was kept at 0.3 torr inside the reactor and the substrate growth temperature was kept constant at 180 ℃. Coated specimens were characterized by x- ray diffraction (XRD) , scanning electron microscope (SEM) , atomic force microscope (AFM) , haze, transmittance and sheet resistance.
With deposition time increasing, the thickness, roughness, haze and grain size increased, and the sheet resistivity and transmittance decreased. On the other hand, the thickness was independent of flow rate and the roughness, haze, grain size and sheet resistivity decreased with flow rate increasing. Among them, the optical and electrical properties of ZnO:B thin film with 1.5μm thickness prepared with B2H6 flow rate at 850 sccm revealed haze 13.4%, sheet resistivity 7.7 ohm/sq and transmittance 87.2%, leading to the chance for producing transparent conduction oxide( TCO) in Taiwan, and reducing the quantity of importation.
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