Reduction of current collapse in AlGaN/GaN MISHEMT with bilayer SiN/Al2O3 dielectric gate stack

We have studied the drain current dispersion characteristics of conventional AlGaN/GaN HEMTs and SiN/Al2O3/-AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MISHEMT) fabricated on silicon substrate. The fabricated MISHEMT exhibited an I-Dmax of >1000 mA/mm and g(mmax) of 241 mS/mm. Compared to conventional AlGaN/GaN HEMTs, about an order of magnitude lower gate leakage current and a similar to 60% reduction in drain current (I-D) collapse was observed in the MISHEMTs. The observation of low I-D collapse is due to the occurrence of low interface state density (6.39 x 10(10) eV(-1) cm(-2)) between the bilayer dielectric (SiN/Al2O3) and GaN surface which is confirmed through the AC-conductance method. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim