PSEUDOMORPHIC INGAAS HIGH-ELECTRON-MOBILITY TRANSISTORS

High electron mobility transistors (HEMTs) with single-quantum-well active layers composed of pseudomorphic InGaAs on GaAs and InP substrates have yielded substantial performance enhancements relative to their lattice-matched equivalents. The higher cut-off frequencies possessed by these devices have enabled new applications to be realized in the millimeter wave spectrum which are not feasible with lattice-matched HEMTs. Also, the devices are beginning to displace GaAs field effect transistors in the microwave spectrum as a result of higher gain and power-added efficiency inherent to the pseudomorphic devices. These developments in transistors and parallel developments in other strained layer material systems and devices have been paced by a resurgence in research and development in the materials science and engineering of strained epitaxial layers.