Improvement of device characteristics in MIS AlGaN/GaN heterostructure field‐effect transistors by designing insulator/AlGaN structures

Abstract

AbstractTo obtain a guideline for improving the device performance of GaN‐based Metal‐Insulator‐Semiconductor (MIS) heterostructure field‐effect transistors (HFETs), both HFET and MIS HFETs were fabricated and compared, whose gate capacitances are designed to be equal. With an increased insulator thickness and decreased AlGaN thickness, a high transconductance was successfully obtained that was equivalent to that of HFET, in addition to the reduced gate leakage current in MIS HFETs. Moreover, Al2O3‐based MIS HFETs were revealed to exhibit superior DC characteristics over Si3N4 MIS HFETs. Since deposition of insulators changes the electrical properties of heterostructures, considering the insulator/AlGaN structures as the total barrier layers is effective and indispensable in designing the MIS AlGaN/GaN HFETs. On the basis of the device design, MIS HFETs can be fabricated that exhibit superior device characteristics over those in conventional HFETs. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)