In this letter, a novel ultra-thin finger-like source region-based tunnel field effect transistor (TFET) (UTS-F-TFET) is used for the implementation of a temperature sensor or resistance temperature detector (RTD). Gate and source contact metal with specific work functions are deposited to provide proper functioning and detection of temperature deviation. Lower band gap material (Silicon-Germanium, SiGe) is used as source material to compensate for the limitation of lower on-state current in the UTS-F-TFET. Horizontal, as well as vertical tunneling with reduced drain-channel interface, conductive oxide (high-k), and exposed source and gate electrode, are the key factors that are used to implement the RTD. on-state current and gate biasing are used to calculate the effective change in resistance with fixed drain bias, so on-state current has opted as the fundamental sensing parameters. The findings of the sensing parameters aid the possibility of using the proposed device for RTD applications.