Influence of the channel electric field distribution on the polarization Coulomb field scattering in AlGaN/AlN/GaN heterostructure field-effect transistors

Abstract

Using the Quasi-Two-Dimensional (quasi-2D) model, the current-voltage (I-V) characteristics of AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) with different gate length were simulated based on the measured capacitance-voltage (C-V) characteristics and I-V characteristics. By analyzing the simulation results, we found that the different polarization charge distribution generated by the different channel electric field distribution can result in different polarization Coulomb field scattering, and the difference of the electron mobility mostly caused by the polarization Coulomb field scattering can reach up to 1829.9 cm2/V·s for the prepared AlGaN/AlN/GaN HFET. In addition, it was also found that when the two-dimension electron gas (2DEG) sheet density is modulated by the drain-source bias, the electron mobility appears peak with the variation of the 2DEG sheet density, and the ratio of gate length to drain-source distance is smaller, the 2DEG sheet density corresponding to the peak point is higher.