Reduction of current collapse in AlGaN/GaN MISHEMT with bilayer SiN/Al 2 O 3 dielectric gate stack

We have studied the drain current dispersion characteristics of conventional AlGaN/GaN HEMTs and SiN/Al 2 O 3 /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 ∼ 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 × 10 10 eV ‐1 cm ‐2 ) between the bilayer dielectric (SiN/Al 2 O 3 ) and GaN surface which is confirmed through the AC‐conductance method. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)