HIGH-PERFORMANCE CAMEL-GATE FIELD-EFFECT TRANSISTOR USING HIGH-MEDIUM-LOW DOPED STRUCTURE

We report an improved camel-gate field effect transistor using a high-medium-low doped channel. A 1000-Angstrom-thick n = 1 X 10(17) cm(-3) GaAs layer is employed to form the camel gate, which prevents the planar-doped barrier from being dropped abruptly. In addition to transition channel, a thin (200 Angstrom) heavily doped (n = 5 X 10(17) cm(-3)) GaAs layer works as the main active channel to enhance the current drivability and transconductance. For our 1.5 X 100 mu m(2) device, the maximum current density of over 850 mA/mm was obtained. Moreover, an enhanced voltage-independent transconductance was also observed. Generally, the device exhibits a transconductance of 220 mS/mm which is compatible to that of MESFETs and is two- or threefold to that of reported camel-gate FETs. In addition, the proposed device demonstrates a large gate voltage swing for high transconductance operation. Due to the excellent device performance, our devices do hold promise for both large signal and digital circuits application, simultaneously. (C) 1995 American Institute of Physics.