Fabrication of highly c-axis oriented ZnO thin films for UV photodetector applications by PECVD

• Main Authors: Wei-Jhih Lin, 林煒智
• Other Authors: Da-Hua Wei
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/uzvd5q

碩士 === 國立臺北科技大學 === 製造科技研究所 === 102 === In the study, metallic zinc thin films were deposited onto c-cut sapphire substrates by plasma enhanced chemical vapor deposition system (PECVD) with Diethylzinc (DEZn) as precursors, after atmosphere annealing at 450 ℃and 550 ℃, metallic zinc thin films will transfer to zinc oxide phase with nanostructure such as nanorods or nanowires, and radio-frequency (RF) magnetron sputtering was used to deposit Pt top electrode onto the ZnO nanorods and nanowires. The as-deposited Pt/ZnO nanocomposite samples were then annealed at 450 ℃ in argon ambiences to obtain optimal Ohmic contacts by RTA which can prevent the efficiency loss of Pt electrodes and ZnO nanorods or nanowires. The crystal structure, surface morphology, optical properties, and wettability of ZnO nanorods and nanowires were analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), photoluminescence (PL), and water contact angle meter, respectively. Moreover, the photoconductivity of the Pt/ZnO nanocomposite was also investigated for UV photodetector application. According to the result of analysis, highly c-axis prefer orientation Zn whisker-like structure were successfully deposited by PECVD, ZnO nanorods and nanowires can be obtained during the annealing process. All the samples exhibit highly photoresponse which I-V characteristics showed the photo current to dark current contrast could almost reach 1.8 order of magnitude. As a result, the ZnO photodetector with coral-like nanostructure showed good ohmic contacts behavior and stable UV photo responsibility after 5 times switching on and off UV illumination for 120s. Also, the ZnO photodetector exhibit super-hydrophobic behavior due to self-assemble nanostructure. However, waterproof UV detectors were successfully fabricated in this research work, and it has deeply potential for ZnO multifunctional devices applications.