Influence of polarization Coulomb field scattering on high-temperature electron mobility in AlGaN/AlN/GaN heterostructure field-effect transistors

The high-temperature electron mobility (HT) of the AlGaN/AlN/GaN heterostructure field-effect transistor (HFET) has been studied in the temperature range 300-500 K. Here, the influence of the polarization Coulomb field (PCF) scattering on mu(HT) in AlGaN/AlN/GaN HFET draws our attention, and the experimental results have revealed that PCF scattering plays a more significant role in the changing trend of the electron mobility versus the two-dimensional electron gas (2DEG) density at high temperature. Moreover, PCF scattering is found to vary with increasing temperature, which is closely related to the variation of the interaction between the additional positive polarization charges underneath the gate contact and the additional negative polarization charges near the source Ohmic contact with temperature. Therefore, PCF scattering is still an important scattering mechanism at high temperature. This finding is of great benefit to the optimization of the performance of AlGaN/AlN/GaN HFET at elevated temperature by designing the appropriate device structure based on PCF scattering.