| Summary: | 碩士 === 國立中興大學 === 精密工程學系所 === 95 === Abstract
This thesis describes the effects of the transparent conducting layers (TCL) on the characteristics of GaN-based light-emitting diodes (LEDs). Two kinds of TCLs were used in this research, i.e. nickel-gold (Ni-Au) and indium-tin oxide (ITO). The performance of the GaN LED samples after three life test conditions such as room temperature (22℃)/room humidity (55% R.H.), high temperature (85℃)/ room humidity (55%R.H.) and high temperature (85℃)/high humidity (85% R.H.) is presented. From the lifetime test results, the mechanism of several typical failure cases such as high forward voltage, over leakage current and luminance intensity decay were discussed. After lifetime test, it was found that the transmittance of the ITO film (83%@470 nm) is higher than that of the Ni/Au TCL (65%). The sheet resistance of Ni/Au TCL (30%) is higher than that ITO TCL (15.7%). Furthermore, the thin-film stress of Ni/Au TCL (35%) is higher than ITO TCL (22.7%). Based on these results, it was confirmed that the ITO TCL is better than Ni/Au TCL for the GaN-based LED applications.
From the study of this thesis, the TCL effects on the GaN-based LED performance in terms of life time data under various temperatures, humidity and driving current conditions were established. This can benefit the device reliability and provide more information about the optimization design of the GaN-based LEDs.
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