| Summary: | 碩士 === 國立臺灣大學 === 電子工程學研究所 === 100 === In this thesis, deep depletion behavior of MOS capacitors with ultrathin oxides is of major concern, while the photoresponse of each sample is also included for better understanding of this behavior. First, MOS capacitors with simple square patterns are fabricated and measured. Accompanied by saturation of gate current, deep depletion behavior occurs when the generation current of minority carriers fails to supply the leakage current. Enhancement of lateral nonuniformity such as illumination or decrease in oxide thickness intensifies the fringing field at edge and makes the saturation current pass through the edge of MOS capacitors more likely.
Subsequently, patterns with various changes in the edge-related parameters are designed so as to further recognize the approximate scales of edge regions. The capacitance-voltage and current-voltage curves of samples with electrode width lager than 10 μm and electrode separation of 30 μm are similar to those with simple square patterns. However, current-voltage curves of samples with electrode separation smaller than 20 μm and electrode width of 30 μm exhibit particular transition regions during the saturation of gate currents. Explanation and illustration are consequently proposed, supposing that the behavior originates from the coupling of edge depletion region and the sharing of minority charges between two adjacent electrodes. Under illumination, the transition regions disappear due to the abundant minority carriers.
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