Polarization Coulomb field scattering in AlGaN/AlN/GaN heterostructure field-effect transistors

Abstract

Using the measured capacitance-voltage curves of Ni Schottky contacts with different contact areas and the current-voltage characteristics for the circular and rectangular AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) at low drain-source voltage, we found that the polarization Coulomb field scattering has an important influence on the two-dimensional electron gas (2DEG) electron mobility in both the circular and rectangular AlGaN/AlN/GaN HFETs. Moreover, the polarization Coulomb field scattering in AlGaN/AlN/GaN heterostructures is relatively weaker compared to that in AlGaN/GaN heterostructures, which is attributed to the AlN interlayer in AlGaN/AlN/GaN heterostructures to enlarge the average distance between the 2DEG electrons and the polarization charges.