Next generation HEMTs

Abstract

The High Electron Mobility Transistor (HEMT) device structure has played a significant role in analog and digital integrated circuit technology since the early 1980s. The development of the HEMT followed a typical path from fundamental studies of materials to device design and modeling. As the HEMT developed, the details of the device layer structure also evolved. In fact, the original GaAs/AlGaAs HEMT is now obsolete, while other HEMT technologies, such as the InGaAs/AlGaAs pseudomorphic HEMT (PHEMT) and the InP based InGaAs/InAlAs HEMT, have fully matured. Most recent work related to PHEMT and InP HEMT technologies has focused on device integration, circuit and system development, device manufacturability, and reliability issues. As such, device performance progress, relatively speaking, has slowed. At HRL we are investigating new combinations of materials which may lead to significant improvements in existing HEMT and PHEMT devices. The focus of our research is mixed antimonide phosphide (SbP) and mixed antimonide arsenide (SbAs) compounds. In particular, AlGaPSb, which can be grown lattice matched to both InP and GaAs, and InAlAsSb on InP. These compounds offer larger energy bandgaps and larger conduction band offsets than the more commonly used compounds (InAlAs for InP HEMTs and AlGaAs for PHEMTs). Hence, they should lead to devices that have higher sheet carrier concentration, higher breakdown voltage, higher turn-on voltage, higher gain, higher current, higher output power, improved power added efficiency, and lower noise figure.