A novel system for systematic microwave noise and DC characterization of terahertz Schottky diodes

An automated system is developed to evaluate a large number Schottky diodes for terahertz applications with respect to their dc and noise characteristics using a highly sensitive noise measurement technique for one port devices. An extensive RF switching matrix allows noise characterization of one port devices at selected frequency points over a bandwidth from 2 to 8 GHz. The measurement principle also accounts for the impedance mismatch between the system and the device under test (DUT). Furthermore, the setup includes an automated three-axis nanopositioning system capable of consecutively contacting many Schottky diodes arranged in a honeycomb array. The highly accurate positioning of the DUT allows to create reproducible contacts with the diodes using electrochemically etched whisker tips. The smooth contacting procedure enables several hundred contacts with the same whisker tip. With this system, we evaluate the statistical distribution of dc and noise parameters of Schottky diodes with an anode diameter of 1 (mu)m within one honeycomb chip. The system helps in optimizing the production parameters of Schottky diodes for terahertz frequencies.