Scaling of two dimensional MESFETs for ultra low power applications

Abstract

Presents new experimental data and simulations of AlGaAs/InGaAs/GaAs two dimensional MESFETs (2D MESFETs) which utilize sidewall Schottky contacts on either side of a very narrow 2D electron gas channel. These devices demonstrate excellent scaling characteristics down to submicron dimensions in both the channel length and the width, which are attributed to the special geometry of the 2D-3D contacts suppressing both the narrow channel effect (NCE) and the drain induced barrier lowering (DIBL). Specifically, when the device was scaled from 1.0/spl times/1.0 /spl mu/m/sup 2/ to 0.8/spl times/0.5 /spl mu/m/sup 2/, output conductance was reduced from 40 mS/mm to less than 1 mS/mm, knee voltage was reduced from 0.75 V to 0.25 V, and the ideality factor was reduced from 1.3 to 1.08, while the threshold voltage became less negative from -0.5 V to 0.3 V as expected. An excellent source-drain breakdown voltage over 10 V, and a current ON/OFF ratio over 105 were also observed. The gate leakage current remains small up to 0.6 V gate bias, demonstrating a good Schottky barrier between the side gates and the 2D electron gas. These characteristics compare favorably with those of a conventional HFET with similar dimensions.