Microcrystalline phase-involved oxygen-rich a-Si:H (hydrogenated amorphous silicon) films have been obtained using catalytic chemical vapor deposition (Cat-CVD) process. Pure SiH4 (silane), H-2 (hydrogen), and 02 (oxygen) gases were introduced in the chamber by maintaining a pressure of 0.1 Torr. A tungsten catalyzer was fixed at temperatures of 1750 and 1950 degrees C for film deposition on glass and crystalline silicon substrates at 200 degrees C. As revealed from X-ray diffraction spectra, the microcrystalline phase appears for oxygen-rich a-SM samples deposited at a catalyzer temperature of 1950 degrees C. However, this microcrystalline phase tends to disappear for further oxygen incorporation. The oxygen content in the deposited films was corroborated by FTIR analysis revealing Si-O-Si bonds and typical Si-H bonding structures. The optical bandgap of the sample increases from 2.0 to 2.7 eV with oxygen gas flow and oxygen incorporation to the deposited films. In the present thin film deposition conditions, no strong tungsten filament degradation was observed after a number of sample preparations. (c) 2005 Elsevier B.V. All rights reserved.