Reduction of real-space transfer in depletion-mode dipole heterostructure field-effect transistors

The real space transfer in depletion-mode dipole heterostructure field-effect transistors (HFETs) has been investigated both theoretically and experimentally. Theoretically, we demonstrate that parallel conduction will be substantially reduced in the dipole HFET and to a smaller extent in the planar-doped HFET when compared to the conventional HFET due to the increased carrier confinement. By measuring the cutoff frequency at various dc biases, the experimental results indicate that a reduced real space transfer effect occurs in the depletion-mode dipole HFETs.