| Summary: | 碩士 === 國立嘉義大學 === 電子物理學系光電暨固態電子研究所 === 102 === In this study, polycrystalline silicon (poly-Si) thin film was prepared on glass substrate by aluminum-induced crystallization (AIC) at low temperature (500 oC); then zinc-oxide (ZnO) thin film was deposited on the AIC-Si substrate (with structure poly-Si /glass) by radio frequency (RF) magnetron sputter system. Field-emission scanning electron microscope (FESEM)、x-ray photoelectron spectroscopy (XPS)、 photoluminescence (PL) 、x-ray diffraction (XRD) 、transmission electron microscope (TEM), and secondary ion mass spectrometer (SIMS) were used to investigate ZnO material characteristics. In order to further study the opto-electronic properties of ZnO thin film grown on AIC-Si, the Schottky diode and ZnO/AIC-Si heterojunction diodes were fabricated.
The first part is the fabrication of Schottky diode. Grow a thin epitaxial silicon (Epi-Si) layer on the AIC-Si as a AIC-Si/Epi-Si substrate, depositing 10-nm Si3N4/ 3-nm a-Si between ZnO thin films and Au electrodes to improve ZnO surface defects and thus the Schottky barrier height was enhanced from 0.687 to 0.832 eV. Also the rectification ratio was increased to 2.04×102 by two orders at ±4 V bias voltage and the photo-to-dark current ratio (responding to 254 nm) is 8.96 at -1 V bias voltage.
In the second part, the ZnO/p-Si heterojunction diodes were fabricated using AIC-Si substrate. We found that the PMMA coating and thin thermal oxide could improve the electrical properties of this devices, leakage current
being reduced and rectification ratio being increased to 1.86×102 at ±5 V bias voltage. The maximum rejection ratio of ultraviolet to visible (320 nm/500 nm) was found in the devices with AIC-Si/Epi-Si substrate, which has a value of 1.08×104 at 8-V reverse-bias voltage. The value is higher than that (2.05×101) of ZnO grown on Si substrate by three orders, attributing to the thin poly-Si film, prepared by AIC, possessing less visible-light absorption.
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