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Keywords:

  • GaN;
  • MOVPE;
  • HEMTs;
  • structure;
  • electrical properties;
  • photoluminescence

Abstract

This paper describes a technique to improve the drain leakage current and current collapse problems with GaN high electron mobility transistors (GaN-HEMTs) for millimeter-wave high-power and high-efficiency amplifiers with very short gate-periphery. To investigate the relationships between the drain leakage, current collapse and crystal quality of an AlGaN buffer structure with a GaN channel layer, we performed analyses with an atomic force microscope (AFM) and examined photoluminescence (PL), lattice strain and electrical characteristics of devices. Through these analyses, we obtained an optimum epitaxial structure to reduce deep-level defect formation in a GaN channel layer. We have clarified the effects of our work for the first time by looking at the correlation between the YL intensity and c-axis lattice constant of a GaN channel layer. Using the optimum epitaxial structure, we minimized the drain leakage current and current collapse of a GaN-HEMT (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)