A test chip for investigation of junctionless FETs as sub-THz electromagnetic radiation detectors is presented. A number of sensors have been included in the chip designed for production on the SOI substrate. The sensors differ one from one another by the presence of an antenna, transistor layout and doping details. A technology for fabrication of transistors with the self-aligned gate and well-controlled gate to n<sup>+</sup> source/drain separation distance has been developed. Results of device simulation and electrical characterization are presented in the paper.