We show that SiO-based intermediate reflectors (SOIRs) can be fabricated in the same reactor and with the same process gases as used for thin-film silicon solar cells. By varying input gas ratios, SOIR layers with a wide range of optical and electrical properties are obtained. The influence of the SOIR thickness in the micromorph cell is studied and current gain and losses are discussed. Initial micromorph cell efficiency of 12.2% (Voc =1.40 V, fill factor=71.9%, and Jsc =12.1 mA cm2) is achieved with top cell, SOIR, and bottom cell thicknesses of 270, 95, and 1800 nm, respectively. © 2007 American Institute of Physics.