Improving the drive current of AlGaN/GaN HEMT using external strain engineering

Abstract

The concentration of the two-dimensional electron gas (2DEG) at the AlGaN/GaN heterojunction is dominated by the stress developed in AlGaN layer. In this work, the output performance of AlGaN/GaN high electron mobility transistors (HEMTs) was improved by depositing a stressed SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> as a passivation layer, and the external strain applied onto AlGaN was measured using Raman spectroscopy. As a result, an improvement in on-state resistance and drive current of the device was attained due to the extra 2DEG concentration induced by the external strain. Also, to determine the strain-induced threshold-voltage shift, the stress distribution over the gate region was analyzed.