Conference Paper

Dark Current Reduction in ZnO-Based MSM Photodetectors with Interfacial Thin Oxide Layer

Nanoptronics Lab., Iran Univ. of Sci. & Technol. Tehran, Tehran
DOI: 10.1109/HONET.2008.4810246 Conference: High Capacity Optical Networks and Enabling Technologies, 2008. HONET 2008. International Symposium on
Source: IEEE Xplore


In this paper the current transport mechanism of ZnO-based metal-semiconductor-metal ultraviolet photodetectors with various contact electrodes is discussed and simulated. The simulation is based on the thermionic emission theory and tunneling effects. It was found that the lowest dark current attributes to the Ru contact electrode. Moreover, it is shown that in order to achieve a large Schottky barrier height on ZnO and more reduction of dark current, one can insert a thin oxide layer between contacts and ZnO layer. The influence of the thickness of the insulator layer on the dark current of the MIS photodetector has also analyzed.

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    ABSTRACT: We report the fabrication of ZnO-based metal–insulator–semiconductor (MIS) and metal–semiconductor–metal (MSM) photodetectors. With 5 V applied bias, it was found that photocurrent to dark current contrast ratios of the ZnO MSM and MIS photodetectors were 2.9 × 10 2 and 3.2 × 10 4 , respectively. It was also found that measured responsivities were 0.089 and 0.0083 A/W for the ZnO MSM and MIS photodetectors, respectively, when the incident light wavelength was 370 nm. Furthermore, it was found that ultraviolet (UV) to visible rejection ratios for the fabricated ZnO MSM and MIS photodetectors were 2.4 × 10 2 and 3.8 × 10 3 , respectively.
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