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Title [LETTER] Effect of Thin Al2O3 Surface Protection Layer on Performance Improvement of AlGaN/GaN HEMT
Authors (Ryun-Hwi Kim) ; (Seung-Hyeon Kang) ; (Bong-Yeol Choi) ; (Jung-Hee Lee)
DOI https://doi.org/10.5573/JSTS.2020.20.5.469
Page pp.469-473
ISSN 1598-1657
Keywords Thin AlGaN layer; Al2O3 surface protection layer; current collapse; RF performance
Abstract We demonstrate the role of thin Al2O3 surface protection layer in improving the device performance of AlGaN/GaN high electron-mobility transistors (HEMTs) The use of the Al2O3 surface protection layer also simplifies device process steps in comparison with conventional SiO2 or Si3N4 protection layer. The Al2O3 layer is very effective not only in protecting the AlGaN surface during ohmic RTP at high temperature, but also in passivating the AlGaN surface to greatly reduce electron trapping into surface states which leads to improved current collapse. And fabrication of the device with gate length of 0.15 μm exhibited high transconductance of 365 mS/mm and drain current of ~943 mA/mm at VGS = 1 V. The device also exhibited very high RF performances such as fT and fmax of 68.4 and 129 GHz, with the maximum output power (Pout) of 2.2 W/mm and power added efficiency (P.A.E.) of 27.3%, respectively.