Access Region Stack Engineering for Mitigation of Degradation in AlGaN/GaN HEMTs With Field Plate

Abstract

Electric field in a device varies as it switches between ON and OFF states. These states have different intensities of electric field and carrier density. The regions having high electric field affects reliability of a GaN-HEMT. In a AlGaN/GaN HEMT, degradation primarily initiates as a result of electric field crowding near its edges. The present work aims at suppressing high electric field in the SEMI-ON state at the field plate edge by incorporating a SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> pocket at its edge. Numerical analysis is performed using a calibrated setup to investigate viability and performance of the proposed device. It is found that the electric field and electron temperature in the SEMI-ON state reduce significantly by incorporating a SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> pocket around the field plate edge in the drain access region. For the device having SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> pocket with diamond and passivation layer thickness kept at 30 nm each, the electric field, carrier temperature, and self heating reduces by 43%, 20%, and 13%, respectively at the field plate edge along with 47% reduction in the thermal resistance.