Al/SRO/Si devices produced on N-type silicon are experimentally characterized to understand their behavior. Different values were used for the nitrous oxide/silane gas flow ratio (Ro) to control the excess silicon. Depending on the silicon excess, the devices could be operated in various modes; from surface accumulation to deep depletion or to a reverse biased PN junction. Modeling of the different devices is presented. © 2002 American Vacuum Society. @DOI: 10.1116/1.1498277#