| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 105 === In this paper, the use of commercial gallium nitride light emitting diode wafers, wafer number ELV (violet light) and FEB (Blue light), in these two wafers to produce a p-i-n photo detector and light emitting diode (LED). The difference between the two devices is mainly the range of the p-type ohmic contact metal ITO area. ITO has the function of spreading or collecting current, but the high absorption rate at short wavelength (violet and ultraviolet light). Therefore, we will discuss the comparison of the basic photoelectric characteristics, external quantum efficiency and responsivity of the two devices.
The two devices are also divided into square and rectangle. In the measurement of the photoelectric characteristics, the purple square p-i-n photodetector and LED, at 10mA current, the optical output power of 3.7 mW and 4.9 mW; the optical output power of rectangle devices is 3.3 mW and 4.4 mW, respectively. The LED optical output power are both higher than p-i-n photo detector. In the external quantum efficiency measurement, when the device reverse bias is 0V, the peak external quantum efficiency of square p-i-n and LED is 22%, 21%, the corresponding peak responsivity is 0.067 A/W, 0.064 A/W, in the short wavelength (330 nm ~ 360 nm), the external quantum efficiency averaged 6.5% and 5.3%. The peak external quantum efficiencies of rectangle p-i-n and LED are 22.9% and 23.3% respectively. The corresponding peak responsivity is 0.07 A/W and 0.071 A/W respectively, and the peak wavelengths at 383 nm. At short wavelengths (330 nm ~ 360 Nm), the external quantum efficiency averaged 6.4%, 5.5%. The peak external quantum efficiency of the two devices are the same, while the short wavelengths quantum external efficiency p-i-n is slightly higher than the LED. Blue light devices measurement are the same as those of violet light devices. In the short wavelength portion, since the p-i-n photodetector has no ITO in the light receiving area, the external quantum efficiency is larger than the LED devices; In the optical characteristics of LED devices ITO range is larger, so that the current can be evenly spread to increase the optical output power, so the optical power is greater than the p-i-n devices.
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