This paper reports a PIN-photodetector modelled and characterized in COMSOL Multiphysics. A highly efficient vertical PIN structure on p-Si substrate has been simulated and the performance of the device measured under broad light ranging from 300-1100 nm. The resultant PIN-Si device shows maximum responsivity of 0.73 A/W for 1010 nm illumination wavelength for 1 V applied bias. The obtained broad optical response i.e., 300-1100 nm along with compact geometry make this device structure an efficient light detector in optical as well as industrial applications.