利用氧化鋅奈米結構於紫外光感測器之應用

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

林煒智(Wei-Jhih Lin)

指導教授 ： 魏大華

國立臺北科技大學/機電學院/製造科技研究所/碩士(2014年)

https://doi.org/10.6841/NTUT.2014.00488

摘要

本論文分為兩大部份，第一部份是利用電漿輔助化學氣相沉積系統製備鋅奈米結構於sapphire(0001)基板上，其中探討沉積溫度對於鋅奈米結構的影響。檢測結果顯示，在沉積溫度100 ℃以下製備出的樣品其形貌為薄膜狀，隨著溫度提高至175 ℃時，其形貌由薄膜轉變為鬚晶狀，所以由此可以得知沉積溫度對於鋅的形貌是有著很大的影響。第二部份是先將鋅奈米結構經由退火爐管進行450 ℃和550 ℃的退火，其檢測結果顯示經由550 ℃退火後的樣品其結晶性質較450 ℃的樣品佳，故選擇經由550 ℃退火的氧化鋅奈米結構來製備金屬-半導體-金屬結構之元件歐姆接觸，先以物理氣相沉積系統鍍上約100 nm的白金電極，接著利用微影蝕刻及舉離法製作指叉狀電極，為了讓電極與材料之間有較高靈敏性及低功率損耗，故利用快速熱退火其製程壓力為5 Torr，退火環境為氬氣，退火溫度為450 ℃、持溫時間為10分鐘。元件接續做電性檢測，發現結構為鬚晶狀的樣品有著較佳的響應，其上升時間為20.5秒，電流增益值為1.8 orders，且經由5次的開關以及相隔120秒後，穩定性以及重現性是相當好，所以本研究成功製備氧化鋅奈米結構及在紫外光檢測器之應用。

關鍵字

電漿輔助化學沉積系統 ； 氧化鋅 ； 歐姆接觸 ； 紫外光感測器

並列摘要

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.

並列關鍵字

Plasma enhanced chemical vapor deposition ； Zinc oxide ； Ohmic contact ； UV detector

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