AlGaN/GaN Polarization-Doped Field-Effect Transistors With Graded Heterostructure

The design, fabrication, and characterization of AlGaN/GaN polarization-doped field-effect transistors (PolFETs) with graded heterostructure are presented in this paper. The 3-D profiles of carriers are obtained across the graded AlGaN/GaN heterostructure grown on a sapphire substrate, which brings about some novel features. The dc transfer and frequency characteristics exhibit bias-insensitive throughout the low- and high-voltage operating regions, demonstrating the potential for high linearity applications. In addition, dynamic I-V measurement was carried out to analyze the trapping behaviors. Negligible current collapses were observed in the unpassivated PolFETs with graded heterostructure, which can be explained in the aspect of unique energy band profiles of AlGaN/GaN graded heterostructures.