Photoconductive properties of a-Si:H films deposited on Si(100) substrates by reactive sputtering at room temperature were characterized as a function of hydrogen concentration in the films and the film thickness. In 230 nm thick a-Si:H films, the difference between dark- and photoresistance increases with increasing hydrogen concentration within the films. The films deposited with an H-2 flow rate of 2 sccm show a dark-resistance of approximately 1 x 10(6) Omega/ and a photoresistance of 2 x 10(4) Omega/. A decrease in the difference between dark- and photoresistance values with increasing film thickness above 230 nm was attributed to the increase of polymeric bonding such as SiH2 within a-Si:H films. a-Si:H films deposited on Si(100) substrates are considered to be suitable for photoconductivity materials in photoconducting sensor applications. (c) 2007 The Electrochemical Society.