Improving the Linearity of GaN HEMTs by Optimizing Epitaxial Structure

This paper presents an effective method of improving the linearity of GaN/AlGaN high-electron mobility transistors (HEMTs) by optimizing barrier (AlGaN Layer) thickness or implementing doped GaN cap or a combination of both. HEMT devices with different epitaxial structures were simulated, fabricated, and measured to demonstrate this. Third-order intermodulation distortion and adjacent channel power ratio measurements were performed in order to compare linearity experimentally. A significant improvement of linearity is observed for an optimized architecture.