Use of high-purity AlxGa1-xAs layers in epitaxial structures for high-power microwave field-effect transistors

The fabrication of high-purity layers of AlxGa1-xAs solid solutions in the range 0 less than or equal to x less than or equal to 0.38 by molecular bea m epitaxy is reported. The low-temperature photoluminescence spectra of the se layers reveal predominantly the free exciton recombination line (X). The narrow width of the X line, the high intensity ratio of this line to that of the band-acceptor transition line, and the linear dependence of the X li ne intensity on the excitation power density in the range between 1x10(-4) and 100 V.cm(-2) indicate a low concentration of background impurities in t hese layers. Using this material in pseudomorphic AlGaAs/InGaAs/GaAs hetero structures for high-power microwave transistors produced devices with a spe cific saturated output power of 0.9 W/mm at 18 GHz. (C) 1999 American Insti tute of Physics. [S1063-7850(99)00308-0].