We report on the development of hydrogenated n-type amorphous and microcrystalline silicon oxides ((n)-SiOx:H and (n) mu c-SiOx:H, respectively) by PECVD, and their successful integration as n-window layers for silicon heterojunction (SHJ) solar cells devices. These Si-oxides were investigated by means of microRaman spectroscopy, high-resolution TEM and time of flight SIMS. Comparatively to (n) mu c-SiOx:H, the (n) a-SiOx:H leads globally to an improvement of the photovoltaic performance, except for open circuit voltage which was higher with the microcrystalline oxide -due probably to a reduction of the parasitic absorption-. The associated temperature coefficients were also investigated towards improving their performance in hot desert conditions.