A systematic collection of voltage reflection data for semi-insulating N-GaN wafer surface along with the reference reflection voltages are accomplished using a very stable continuous wave (CW) frequency stable probe source. The 2″ diameter direct-bandgap 5 µm silicon doped 10 Ω-cm GaN on 434 µm sapphire is a commercial sample and was mounted in the path of collimated BWO generated millimeter wave beam with spot size ∼3 mm and rotated 64.5° to millimeter wave reflected energy into an antenna fed zero-bias Schottky barrier diode (ZBD), a negative polarity detector with responsivity 3.
View Article and Find Full Text PDFVoltage data acquired after probe signal transmitted through the organic film and reflected off the film surface as a function of 0.36 mW millimeter wave signal frequency in the range 110-160 GHz. Five different organic photovoltaic (OPV) materials and one 95:5 blend produced at 2 spin rates are used.
View Article and Find Full Text PDFThis article demonstrates a contactless, time-resolved, millimeter wave conductivity apparatus capable of measuring photoconductivity of a diverse range of materials. This cavity-less system determines the time-dependent magnitude of a sample's charge carrier density-mobility product by monitoring the response of a continuous, millimeter-wave probe beam following excitation of the sample by an ultrafast laser pulse. The probe beam is tunable from 110 GHz to 170 GHz and the sample response data can be obtained over the sub-nanosecond to millisecond time interval.
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