This work presents a comparative study between MIS photodiodes produced using high quality amorphous silicon (a-Si:H), deposited by PECVD at 2Angstrom/s, using 13.56 MHz frequency and polymorphous silicon (pm-Si) deposited at 3Angstrom/s using a 27.12 MHz frequency. The results show that the pm-Si:H outperforms the a-Si:H MIS photodiodes by having a rectification ratio of 10(7), and photosensitivity at AM1.5 conditions of 10(7), Under 1V reverse bias. Apart from that, the pm-Si:H photodiode presents a higher open circuit voltage and better fill factor than a-Si:H MIS photodiode. These results prove that quality devices can be produced at high growth rates by using pm-Si:H. In this work the photodiode performances were correlated to the films properties, aiming to determine the characteristics responsible for the performances exhibited by the pm-Si:H devices.