We report fabrication of AlGaN/GaN high electron mobility transistor (HEMT) with improved DC, high frequency and microwave power performances by employing a two-step passivation approach. A pretreated AlGaN surface is provided by dry etching n(+)-GaN cap layer and RTA annealing ohmic contacts right before Si(3)N(4) passivant is deposited. No additional process step is associated with the surface preparation for the passivation process. Pulsed I-V characteristics show that the proposed passivation process successfully eliminates trapping effect at Si3N4 and AlGaN interface and is considered to be the important factor for the performance enhancement. (C) 2010 Wiley Periodicals, Inc. Microwave Opt Technol Len 52: 1614-1619, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25266
