Program Summary
Today’s state of the art (SoA) microwave and millimeter wave power amplifiers have been made possible by the creation of lateral and vertical heterojunction semiconductor devices, such as high electron mobility transistors (HEMTs) and heterojunction bipolar transistors (HBTs), respectively. To meet future mission requirements for longer range operation, wider bandwidth, and link robustness, power amplifiers with higher output power than can be achieved with today’s SoA are needed. This in turn will demand radio frequency (RF) device structures that simultaneously exhibit higher charge density, higher breakdown field, good carrier transport properties, and high thermal conductivity. Researchers have theorized that potentially game changing device structures can be formed by integrating dissimilar materials to solve current device performance limitations, but have not succeeded in realizing these devices, primarily due to poor interface quality between dissimilar materials, which degrades the electronic properties.
The Heterogeneous Heterostructures (H2) Microsystems Exploration (μE) topic aims to create a new path for realizing high power density, microwave, and millimeter wave devices by demonstrating heterogeneous heterojunctions. In particular, the H2 μE seeks to explore and develop approaches to create low defect density interfaces between dissimilar materials. These approaches will be used to create heterojunctions with low defect density and heterostructures that simultaneously exhibit high charge density, high breakdown field, good carrier transport properties, and high thermal conductivity.
The target outputs will support the creation of RF transistors with a 10X increase in power density compared with today’s SoA.