The electrical properties of oxynitride films on strained SiGe grown and deposited, respectively, using a N2O and a combination of N2O and hexamethyldisilazane (HMDS) plasma are reported. X-ray photoelectron spectroscopy (XPS) analysis of the N2O grown films have shown the incorporation of N at the oxide interface without any Ge segregation. The hole confinement in accumulation in SiGe/Si heterostructure with 90 Å N2O oxynitride film has been observed by C-V measurements. Plasma reoxidation of N2O grown dielectric films has resulted in significant improvement of electrical properties. Oxynitride films deposited using PECVD of HMDS have shown comparatively inferior properties. Films deposited from a mixture of N2O and HMDS, exhibit the highest value of Dit (1x1012 cm-2eV-1), probably due to higher amount of nitrogen incorporation at the interface. The charge trapping behavior of both the grown and deposited films have been studied. The effect of addition of NH3 in HMDS plasma and N2O oxidation prior to HMDS PECVD on the charge trapping behavior has been studied.