Detection of THz Radiation by SOI Sensors

M. Zaborowski, D. Tomaszewski, J. Malesinska (Institute of Electron Techn., Poland), P. Zagrajek (Military Univ. of Techn., Poland)

N-channel junctionless FETs (nJLFETs) with patch antennas have been manufactured using SOI wafers. The sensors exhibit 30µV DC photoresponse to 0.34THz EM radiation. Measurements of their I-V characteristics and sub-THz response characteristics are reported. An ability to influence the sensitivity by substrate biasing has been investigated. The data obtained for the standard nMOSFETs sensors are given as a reference. The experimental results reveal different behavior of two types of the sensor devices. For the interpretation of these dissimilarities numerical simulations of the JLFET electrical characteristics have been used. Based on the experimental data and on the modeling, a problem of the EM energy transport efficiency in the FETs has been discussed, which is one of the key factors limiting the FET sensitivity to the THz radiation. The proposed approach has been used for an interpretation of the photoresponse characteristics of the JLFETs with the non-uniform doping level in the channel, obtained by the non-standard processing conditions.