In this study the infrared photoconductive detectors works at far infrared region and at room temperature were fabricated. The detector fabricated using four types of CNTs (MWCNTs, COOH- MWCNTs, short- MWCNTs and DWCNTs). The CNTs suspension is deposited by dip coating and drop -casting techniques to prepare thin films of CNTs. These films are grown on PSi substrates of n-type and p- type Si. The aluminum electrodes were evaporated on the CNTs film to fabricate the far IR detectors. The detectors were illuminated by 2.2 and 2.5 Watt from CO2 of 10.6 micrometer and tested. The surface morphology for the films is studied using AFM and SEM micrographs. The films show homogeneous distributed for CNTs on the PSi layer. The root mean square (r.m.s.) of the films surface roughness indicates a smooth surface of the synthesized films. The Raman spectrum at room temperature for MWCNTs, are dominated by the two typical lines at about 1335.4 cm-1 (D line) and 1563.2 cm-1 (G line) assigned tothe disorder induced by defects and curvature in the nanotubes lattice, and to the in-plane vibration of the C-C bonds, respectively.