Effect of the side-Ohmic contact processing on the polarization Coulomb field scattering in AlN/GaN heterostructure field-effect transistors

Using the measured capacitance–voltage and current–voltage characteristics of the rectangular AlN/GaN heterostructure field-effect transistors（HFETs） with the side-Ohmic contacts, it was found that the polarization Coulomb field scattering in the AlN/GaN HFETs was greatly weakened after the side-Ohmic contact processing, however, it still could not be ignored. It was also found that, with side-Ohmic contacts, the polarization Coulomb field scattering was much stronger in AlN/GaN HFETs than in Al GaN/AlN/GaN and In0：17Al0：83N/AlN/GaN HFETs, which was attributed to the extremely thinner barrier layer and the stronger polarization of the AlN/GaN heterostructure.