High temperature operation of narrow channel AlInAs/InGaAs/AlInAs 3D-SMODFETs for power amplifiers

Abstract

Using a modulation doped field effect transistor (MODFET) with a pseudomorphic parabolically graded channel and atomic planar doped pseudomorphic barriers on both sides of the channel, it is possible to achieve record-breaking electron sheet densities in the channel without having carriers in the barrier (Double-Doped Double-Strained MODFET, 3D-SMODFET). Designing double-doped MODFETs with stress compensation allows the total thickness of all the pseudomorphic layers to be extended beyond any one critical layer thickness value. Using a simple analytical method, an optimum material structure for AlInAs/InGaAs/AlInAs 3D-SMODFETs with narrow full channels is shown. These narrow channel 3D-SMODFETs on InP show minimal short channel effects (output conductance <15 mS/mm) at elevated temperatures with good pinch-off characteristics and RF performance (f/sub MAX/ to f/sub T/ ratio of 3).