Device considerations and characterisations of double-channel GaAs pHEMT Schottky diodes for limiter applications

We report on the device considerations and discuss the design and fabrication of 0.5 μm gate length double-channel GaAs pHEMT well-suited for diode based limiter applications. I-V, C-V and RF characterisations of GaAs pHEMT Schottky diode that is used in the limiter applications have been presented. The presence of double channel is discussed and clearly observed from the doping curve of 1/C2 versus V plot. Double channel layers provide wide-ranging usages in linear application. Based on the measured DC and RF parameter extractions, an equivalent circuit model of the pHEMT Schottky diode is derived. All six unknown model parameters are extracted using direct parameter extraction method. The measured results show good agreement with the modelled over the frequency range from 0 to 40 GHz for operation bias range.