CW performance of vapor-grown GaAs transferred electron oscillators

The CW performance of GaAs transferred electron oscillators (TEO) is described. The TEO were fabricated from n⁺-n-n⁺epitaxial structures of GaAs grown from the vapor phase. The devices consisted of single mesas, 5-6 mil in diameter, on plated silver heat sinks. Fifteen devices were fabricated from three separate wafers and the results were very uniform. The dc to RF efficiency varied between 4 and 5.7 percent for the 15 devices packaged and tested. The best results were 350 and 390 mW of RF power with a conversion efficiency of 5.4 and 5.7 percent, respectively, at approximately 17.5 GHz from single 5.5-mil mesas. These data represent new highs in performance from single-mesa TEO at this frequency. The results indicate that vapor epitaxial growth procedures combined with a device fabrication scheme based on plated heat sink technology can yield reproducible TEO with RF powers greater than 250 mW at efficiencies greater than 5 percent. The results indicate also that the plated heat sink approach will be useful for other devices, such as IMPATTS, in which thermal considerations limit device performance.