An Overview on Analyses and Suppression Methods of Trapping Effects in AlGaN/GaN HEMTs

Abstract

Due to the excellent material characteristics, AlGaN/GaN HEMTs are widely used in high power and high frequency applications. However, the existence of damages, defects and dislocations still degrade the device features because of trapping effects. In this paper, investigations of trapping effects are summarized and discussed to understand the inner mechanism, including the gate-lag and drain-lag transient responses, the current collapse of pulsed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{I}_{\mathrm {DS}}$ </tex-math></inline-formula> - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{V}_{\mathrm {DS}}$ </tex-math></inline-formula> , the dependence of frequency dispersion, the transient current reduction with pulsed-RF excitation and the kink effect. In addition, recent methods of suppressing trapping effects are reviewed, including surface passivation, GaN cap layer, gate/source field plate, buffer engineering and structure modification. The profits and shortages of each method are compared and discussed.