Gate-quality ultrathin silicon dioxide films on strained-Si0.74Ge0.26 layers have been deposited by microwave plasma-enhanced chemical vapor deposition technique using tetraethylorthosilicate. Effect of nitric-oxide (NO)-plasma treatment on the electrical properties of the deposited oxides have been studied using a metal–insulator–semiconductor structure. A significant improvement in the interface trap level density (Dit) and charge trapping behavior under Fowler–Nordheim constant current stressing is observed for NO-plasma treated deposited oxide films.