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ABSTRACT This letter reports the highest fundamental oscillator operating frequency of 120 GHz for gallium arsenide (GaAs)-based Gunn diode. The letter describes the design, fabrication, and test of the aluminum gallium arsenide (AlGaAs)/(GaAs) planar Gunn diode with an anode to cathode separation of 1 μm and channel width of 120 μm. The planar Gunn diode was designed with an integrated series inductor in coplanar waveguide format. The experimental results showed that the planar Gunn diode oscillated at a fundamental frequency of 120.47 GHz with an RF output power −9.14 dBm. This is highest fundamental frequency and power recorded for a GaAs-based Gunn diode. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2449-2451, 2014 [ABSTRACT FROM AUTHOR]

A highly efficient and accurate extraction algorithm for the small-signal equivalent-circuit parameters of a GaN high electron-mobility transistor device is presented. Elements of the extrinsic equivalent-circuit topology are evaluated using a modified "cold field-effect transistor" approach whereby the undesirable need to forward bias the device's gate terminal is avoided. Intrinsic elements are determined based on a circuit topology, which identifies, for the first time, a time delay in the output conductance of GaN-based devices. The validity of the proposed algorithm has been thoroughly verified with excellent correlation between the measured and modeled S-parameters up to 50 GHz. [ABSTRACT FROM AUTHOR]

Temperature measurements have been made on Gunn diode samples, using both infrared (IR) and micro-Raman spectroscopy. Micro-Raman spectroscopy was used to give high-resolution temperature measurements on the active transit region of the Gunn diode. These were directly compared with IR thermal measurements made across the mesa region and also on the metallized top contact of the diode. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel method of introducing a notch at a point of high magnetic field in a coplanar waveguide (cpw) radial and diamond stub resonator to increase the quality factor (Q) was analyzed. For comparison, both radial- and diamond-shaped cpw resonators with and without notches were fabricated on gallium arsenide (GaAs) semi-insulating substrate at the James Watt Nanofabrication Centre and tested in the milli-metric laboratory at University of Glasgow. The notch increased the loaded Q factor of the diamond resonator by approximately 28% and good agreement was obtained between the measured and simulated loaded Q for both cpw radial and diamond resonators. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1323-1325, 2015 [ABSTRACT FROM AUTHOR]