Enhanced effect of strain-induced polarization Coulomb field scattering in AlN/GaN heterostructure field-effect transistors

摘要

Using the measured Capacitance-Voltage and Current-Voltage characteristics of the rectangular AlN/GaN Heterostructure Field-Effect Transistors (HFETs) with different Schottky areas, we found that after device processing the polarization Coulomb field (PCF) scattering is induced and has an important influence on the two-dimensional electron gas electron mobility. Moreover, it was also found that PCF scattering has an enhanced influence on the mobility in AlN/GaN HFETs compared to that in AlGaN/AlN/GaN HFETs. This is attributed to the large lattice mismatch between AlN and GaN necessitating a thinner AlN barrier layer, which gives rise to a stronger converse piezoelectric effect.