Drain Schottky contact influence on low-field transport characteristic of AlGaN/GaN heterostructure field-effect transistors

Gate-channel electron low-field transport characteristic is obtained from measured current–voltage and capacitance–voltage curves for the AlGaN/GaN heterostructure field-effect transistors (HFETs) with drain Schottky contact and drain Ohmic contact. The electron mobility curve of the HFET with drain Schottky contact shows larger value and slower rising trend, comparing with that of traditional drain Ohmic contact. This phenomenon is investigated qualitatively and quantificationally, in the view of polarization scattering effect. In addition, it is found that different transport characteristics originate from different polarization charge distributions near drain electrode. Since drain Schottky contact does not suffer from thermal annealing process, there is no polarization charge variation, inducing weaker scattering intensity and thus larger electron mobility. It offers a special perspective for the future optimization of AlGaN/GaN HFETs.