Memory And Photovoltaic Devices With Ultrathin Oxide Layers
| Autor: | Chang, Tzu-Yueh, 張資岳 |
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| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 In this dissertation, we study three green devices using ultrathin oxide layers: two organic bistable devices (OBDs) and one metal-insulator-semiconductor (MIS) solar cell. The ultrathin oxide layers not only can help realize the resistance switching of the OBDs and recognize the corresponding mechanisms, but also can reduce the reversed saturation current of metal-semiconductor solar cells and thus can ameliorate the open-circuit voltage (Voc) of the solar cells. First of all, the properties of an OBD using an n-type Si/Alq3/Al structure are investigated. The bistable effect of the OBD is primarily caused by the interface defects at the Alq3/Al interface. It is worthy to mention that the electrical properties of the OBD can be modified and controlled by utilizing the appropriate deposition rate of the Alq3 thin film. To understand these phenomena, we use high resolution X-ray photoelectron spectroscopy to analyze the chemical composition of the Alq3/Al interface and Alq3 thin films, and atomic force microscopy and grazing incident X-ray diffraction to characterize the properties of Alq3 thin films. Furthermore, the electrical properties of an OBD with a p+-Si/Alq3/nanostructured MoOx/Alq3/Al structure are also investigated. The bistable switching of the OBD attributes to the charge trapping/erasing in the MoOx nanoclusterlike layer interposed between the Alq3 thin films. After charges are trapped in the MoOx nanoclusterlike layer (the high conductance state), the carrier transportation of the OBD will be dominated by a space-charge field which results from trapped charges. Both the retention measurement and write-read-erase-read cycles of the OBD are also provided. Finally, a stacking MIS solar cell structure, which integrates an n-type MIS solar cell with a p-type MIS one, is proposed to effectively enlarge Voc. The measured Voc is up to 0.71V under simulated air mass (AM) 1.5 illumination (100 mW/cm2). This Voc is larger than those of the n-type or p-type MIS solar cells published. Here we successfully demonstrate the feasibility of the Voc enhancement of MIS solar cells by using a stacking structure. The stacking MIS solar cell will play an important role in photovoltaic application for hydrogen generation. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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