| Summary: | 碩士 === 逢甲大學 === 電子工程學系 === 106 === In this thesis, the ultrasonic spray pyrolysis deposition which has benefits of low-cost and room-temperature operation is used to deposit n-type MgZnO on the p-type GaN to form pn heterojunction. Ti/Al and Ni/Au are deposited by the thermal evaporator to serve as the cathode and the anode of the diode. The present diode can be used as light-emitting diode and photodiode.
In order to understand the properties of MgZnO thin films which is deposited by the ultrasonic spray pyrolysis deposition, the following material characterization techniques are used including: (1) photoluminescence, the emission wavelength of the MgZnO thin film, (2) X-ray photoelectron spectroscopy, the composition of the MgZnO thin film, (3) X-ray Diffractometer, the crystal structure of the MgZnO thin film.
The current versus voltage characteristic, light output power versus injection current characteristic, and emission wavelength spectrum characteristic are measured. The turn-on voltage of the light-emitting diode is 3.7V, the light output power is 3.4.mW. The emission wavelength occurs blue shift when the Mg contents increase. For estimate the performance of the photodiode, the diode is applied negative bias and the following characteristics are measured including, spectral photoresponse, detectivity, UV-to-visible rejection ratio, and response time characteristics. The photodiode has the largest photoresponse 16.4A/W at 350nm, and with increase of Mg content, the sensing wavelength also blue shift from 350nm (Mg0.1Zn0.9¬O) to 310nm (Mg0.4Zn0.6O).
MgZnO/GaN heterojunction optoelectronic diodes are fabricated successfully. The operation mode of the diode is controlled by the polarity of the applied voltage. When the positive voltage is applied, the diode is used as the light-emitting diode. When the negative voltage is applied, the diode is used as the photodiode.
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