In this work, TCAD-based investigation of junctionLess (JL) architecture having double gate (DG) has been performed for visualizing the sensitivity of the device against light intensity. Comparison has been drawn between conventional DG MOSFET and DG-JL transistor (DG-JLT) under dark and light conditions. Effect of light intensity and wavelength has been modulated to optimize the device sensitivity. Higher shift in the drain current (in subthreshold region) has been observed at 0.35 μm of wavelength, i.e., more sensitive to ultraviolet (UV) light. The improved sensitivity of DG-JLT as compared to DG-MOSFET is due to the better subthreshold characteristics of the device (i.e., lower leakage current and subthreshold slope). From the results, it can be concluded that the DG-JLT with channel doping of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">19</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , 10 nm of channel thickness, and having 1 nm of oxide thickness is the best possible choice for UV photodetector due to high sensitivity and responsivity. It has also been observed that more optimizing parameters are available with DG-JLT as the DG-MOSFET is immune toward the device parameter variation.