Channel conductivity of high frequency field effect transistor designed on nitride semiconductors

Abstract

The conductivity of the n-channel of a field effect transistor designed on nitride semiconductors is investigated in this paper on the basis of the created model. The transistor contains two parts - vertical and horizontal structures. The vertical structure contains three layers n-In/sub 0.5/Ga/sub 0.5/N-p-In/sub 0.5/Ga/sub 0.5/N-GaN (nondoped). The conductivity of the top layer GaN (nondoped) is ruled by tunnel injection of electrons coming from the border of p-In/sub 0.5/Ga/sub 0.5/N-GaN (nondoped). The top layer GaN (nondoped) belonging to the vertical structure acts as the FET channel of the horizontal field effect transistor - n-GaN-GaN (nondoped)-n-GaN. The vertical structure is modeled by an equivalent circuit model of an n-p-n bipolar transistor having floating base. The horizontal structure is modeled by an equivalent circuit model of an n-channel FET where the influence of the vertical structure (giving the channel conductivity) is accounted for by a virtual generator. The results of the investigation are reported.