Direct-coupled FET logic circuits on InP

Abstract

A process technology for direct-coupled FET logic (DCFL) circuits on InP substrates, based on enhancement-mode InGaAs/InAlAs heterostructure-insulated-gate FETs (HIGFETs) is discussed. Its performance was demonstrated by fabricating 11- and 19-stage ring oscillators. The circuits were fabricated on undoped lattice-matched heterostructures grown by molecular beam epitaxy (MBE), using a refractory-gate process with self-aligned sidewalls to achieve a lightly-doped-drain (LDD) structure. For a gate length of 1.2 mu m, with V/sub dd/=2 V, the best propagation delay observed was 23 ps/stage, with associated power of 2.2 mW/stage.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>