MOSFET Characteristics for Terahertz Detector Application from On-Wafer Measurement

In this paper, we report on MOSFET characteristics for terahertz (THz) detector application from precise on-wafer measurement, and the results are compared with theories and SPICE simulations. Techniques for precise measurement using a vector network analyzer and on-wafer probing and simulation based on the SPICE model are introduced. Several MOSFETs in various channel dimensions are fabricated in 65-nm CMOS technology and measured over gate bias voltage and the operating frequencies of 110, 200, and 300 GHz using the lock-in technique. The behavior of responsivity and noise equivalent power (NEP) depending on the channel width and length of the MOSFET and the frequency are investigated, and trends of the obtained results are in good agreement with the theories and the simulations. The channel width dependence of the responsivity of the MOSFET detector is evaluated and explained for the first time. The results of this work can provide a reliable and useful reference for the design of THz detectors.