Ni/Au Schottky gate oxidation and BCB passivation for high-breakdown-voltage AlGaN/GaN HEMT |
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Authors: | Min-Woo Ha Seung-Chul Lee Soo-Seong Kim Chong-Man Yun Min-Koo Han |
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Institution: | aPO BOX 50, School of Electrical Engineering, Seoul National University, Shinlim-dong, Gwanak-gu, Seoul 151-742, Republic of Korea;b82-3, Dodang-gong, Wonmi-gu, Fairchild Semiconductor, Bucheon, Gyunggi-do 420-711, Republic of Korea |
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Abstract: | A new AlGaN/GaN high electron mobility transistor (HEMT) employing Ni/Au Schottky gate oxidation and benzocyclobutene (BCB) passivation is fabricated in order to increase a breakdown voltage and forward drain current. The Ni/Au Schottky gate metal with a thickness of 50/300 nm is oxidized under oxygen ambient at 500 C and the highly resistive NiO is formed at the gate edge. The leakage current of AlGaN/GaN HEMTs is decreased from 4.94 μA to 3.34 nA due to the formation of NiO. The BCB, which has a low dielectric constant, successfully passivates AlGaN/GaN HEMTs by suppressing electron injection into surface states. The BCB passivation layer has a low capacitance, so BCB passivation increases the switching speed of AlGaN/GaN HEMTs compared with silicon nitride passivation, which has a high dielectric constant. The forward drain current of a BCB-passivated device is 199 mA /mm, while that of an unpassivated device is 172 mA /mm due to the increase in two-dimensional electron gas (2DEG) charge. |
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Keywords: | GaN AlGaN BCB Passivation |
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