| Summary: | 碩士 === 國立中央大學 === 光電科學研究所 === 96 === Chip process technology of GaN-based light-emitting diodes includes wire-bonding, flip-chip, thin-GaN, and so on. However, wire-bonding and flip-chip are inappropriate for high-power LED chips due to high thermal resistance of sapphire substrates. In this thesis, the GaN thin flim is packaged on a material with higher thermal conductivity, silicon substrates, by wafer bonding technology and laser lift-off.
In the fabrication process of thin-GaN LED, we discover that the coverage and the denseness of passivation effect the reverse leakage current of LED. Further, plasma damage and series resistance also degrade the forward voltage of LED. To improve the leakage current of thin-GaN LED, a highly dense passivation made of SiO2 is utilized; leakage current achieves -0.15uA at reverse voltage of -5V. Also, Ni thin film applied to avoid damage caused by plasma is in order to ameliorate the forward voltage of thin-GaN LED. Moreover, decrease of series resistance is achieved by u-GaN removal, which is to reduce the forward voltage of thin-GaN LED.
The best forward voltage of our fabricated thin-GaN LED is 3.6V approximately; nevertheless, it still need to be improved more compared to the reference. A platform of thin-GaN LED chip process is established for improving the electrical characteristics of thin-GaN LED is utilized by wafer bonding and laser lift-off.
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