We report on an adjustable interferometric set-up for Scanning Microwave Microscopy. This interferometer is designed in order to combine simplicity, a relatively flexible choice of the frequency of interference used for measurements as well as the choice of impedances range where the interference occurs. A vectorial calibration method based on a modified 1-port error model is also proposed. Calibrated measurements of capacitors have been obtained around the test frequency of 3.5 GHz down to about 0.1 fF. Comparison with standard vector network analyzer measurements is shown to assess the performance of the proposed system.
We report on an emerging GaN double heterostructure grown on silicon, which enables the simultaneous achievement of high breakdown voltage and high frequency performance. The use of an AlN barrier layer capped by an in situ SiN layer, and the introduction of an AlGaN back barrier layer in addition to standard field plates enabled the achievement of a remarkable three-terminal breakdown voltage V BK of over 100 V together with a power gain f max above 200 GHz for the first time on GaN devices grown on silicon substrates. This results in a record combination of f max V BK of above 20 THz V, promising breakthrough performance for widespread millimeter-wave applications.
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