Edge-Dependent I-V Behavior of MOS Structures with Ultrathin Oxides under Inversion Region
| Autor: | Pei-Lun Hsu, 徐培倫 |
|---|---|
| Rok vydání: | 2013 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 In this thesis, edge-dependent I-V behavior of MOS structures with ultrathin oxides is investigated. Samples with various electrode separations are fabricated and measured in order to understand how edge-related parameters influence tunneling current behavior. We observe two major phenomena from I-V curves when samples are under inversion region: First, the magnitude of saturated currents increases with the electrode separations. Second, I-V curves of samples with electrode separation smaller than 20 um exhibit particular transition regions during the saturation of gate currents. Explanation and illustration are consequently proposed with the help of simulation, supposing that the behavior originates from the changes of minority carrier diffusion currents outside the depletion region. A model that states how hole and electron tunneling currents both control the gate current based on the experimental result is also purposed in order to further explain the tunneling current mechanism under inversion region. Under illumination, the photocurrents are still influenced by edge diffusion currents. However, due to the quick saturation of hole tunneling current, the gate tunneling current is dominated by hole tunneling current, and transition regions disappear. Subsequently, in order to confirm the effect of electron diffusion current on the I-V behavior, patterns with split electrodes and various electrode separations are designed. The I-V curves of new samples exhibit opposite behavior compared to the aforementioned samples; saturated gate currents decrease as the electrode separations increase under inversion region when the bias of outside ring electrode is floating. Since we know that the tendencies of diffusion currents are distinct between two groups of samples because of distinct edge-related electron concentration profiles by simulation, this result perfectly confirms that diffusion current in edge is one of the major reasons that dominates the I-V behavior under inversion region. When under illumination, the saturated photocurrents also exhibit decrements as the electrode separations increase due to the effect of diffusion current. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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