On the step-graded doped-channel (SGDC) field-effect transistor

An i-InGaP/n-InxGa1-xAs/i-GaAs step-graded doped-channel field-effect trans istor (SGDCFET) has been fabricated and studied. Due to the existence of a V-shaped energy band formed by the step-graded structure, a large output cu rrent density, a large gate voltage swing with high average transconductanc e, and a high breakdown voltage can be expected. In this study, first, a th eoretical model and a transfer matrix technique are employed to analyze the energy states and wavefunctions in the step-graded quantum wells. Experime ntally, for a I x 80 mu m(2) gate dimension device, a maximum drain saturat ion current density of 830 mA mm(-1), a maximum transconductance of 188 mS mm(-1), a high gate breakdown voltage of 34 V, and a large gate voltage swi ng 3.3 V with transconductance larger than 150 mS mm(-1) are achieved. Thes e performances show that the device studied has a good potentiality for hig h-speed, high-power, and large input signal circuit applications. (C) 1999 Academic Press.