  A detailed electrical characterization of high-performance bow-tie InGaAs
based terahertz detectors is presented along with simulation results. The local
surface potential and tunnelling current were scanned over the surfaces of the
detectors by means of Kelvin probe force microscopy (KPFM) and scanning
tunnelling microscopy (STM), which also enabled the determination of the Fermi
level. Currentvoltage curves were measured and modelled using the Synopsys
Sentaurus TCAD package to gain deeper insight into the processes involved in
detector operation. In addition, we performed finite difference time-domain
(FDTD) simulations to reveal features related to changes in the electric field
due to the metal detector contacts. The investigation revealed that field
effect-induced conductivity modulation is a possible mechanism contributing to
the high sensitivity of the studied detectors.
