LT-GaAs-MIS-diode characteristics and equivalent circuit model

Abstract

LT-GaAs MISFETs had been realized indicating a record 2.7 W/mm RF power handling capability. To optimize such LT-GaAs power MISFET structures, the MIS system containing a LT-GaAs insulator and an AlAs interfacial diffusion barrier to the channel has been analyzed. A noticeable parallel conductance was found in the insulator which is thought to be one of the key parameters to realize high gate to drain breakdown voltages. This conductivity however leads also to a g/sub m/-dispersion in the MHz range. Locus-curves of this system demonstrate a higher resistivity in the AlAs layer than in the LT-GaAs layer, indicating that the simple model of a single lossy capacitance does not describe the MIS diode completely. An extended electronic equivalent circuit for use in the FET model has been established.<>