GaAs-Ge Alloys for High-Speed Transistors

If you need high-speed, high-power transistor today, you'll probably opt for an HBT (heterojunction bipolar transistor). And you'll have to put up with its limitations, some of which are due to dopants moving from their proper place in the structure. But Spire thinks it can improve the growth process by building HBTs which use an inherently p+ GaAs-Ge alloy, getting around the problem of dopants creeping out of the base region during materials deposition. What's more, by replacing hard-to-make aluminum-containing compounds with GaAs-Ge, Spire can make HBTs better and cheaper. Best of all, by choosing the right alloy, HBTs can be grown directly on GaAs wafers, then integrated with other electronic and optoelectronic devices. The payoff, say Spire's commercialization-minded engineers, will come when their HBTs show up in the micro- and millimeter wave amplifiers powering radar and mobile communication systems.