| Summary: | 碩士 === 國立成功大學 === 微電子工程研究所 === 102 === In this study, I investigated methods to form CuAlO2 film using Al2O3 substrate, and its application to UV detector. I sputtered a Cu film on Al2O3 substrate followed by electrochemical plating(ECP) Cu2O film on the Cu coated Al2O3 substrate. A CuAlO2 film can be formed by annealing Cu2O/Cu/Al2O3 films at 1100 °C for 12 hours in air.
At first, I used Mo coated Si wafer as substrate and used many different processes to grow CuAlO2 film. The XRD results indicate that CuAlO2 film can be formed, however, Cu will diffuse through Mo film and into the Si substrate after the long annealing time at high temperature. Thus,Al2O3 substrate was used to replace the Mo coated Si substrate.
The experimental results show that the Cu2O thickness determines the exact time it required for the high temperature annealing. For the same thickness of Cu2O film, it reacts with Al2O3 substrate and forms CuAl2O4 and CuO films if over oxidation, but the reaction is not complete if the annealing time is not sufficient. The annealing time temperature, and Cu2O thickness are the key parameters to form CuAlO2 film using Al2O3 substrate. The study used scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffractometer (XRD), and Alpha Step to analyze film’s morphology, element’s composition, crystalline phase/orientation, and film thickness respectively.
Lastly, evaporation of Al film and lift-off process were used to form the electrodes of the photo detector followed by I-V measurements. When the electrode spacing is 5 μm and bias voltage is set at 6 V, I obtained: dark current of 3.73×10-6 A and photocurrent of 1.0×10-5 A under 85W Xenon light illumination. It shows about 3 times of photocurrent amplification.
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