An implanter without an ion mass analyzer has been used to successfully fabricate silicon on insulator (SOI) materials by H2O+, HO+, and O+ ion implantation using water plasma. Based on the consideration that the masses of those three ions are very close, this fabrication makes it possible to form a single buried oxide (BOX) layer by choosing the appropriate implantation energy and dose. Cross-sectional transmission electron microscopy results indicated that the BOX thickness of the SOI materials fabricated using a water plasma approach is increased more than 50% over that made by the conventional separation by implantation of oxygen (SIMOX) process. Secondary ion mass spectroscopy depth profile analysis on the as-implanted wafers showed that there are two hydrogen enrichment peaks around both sides of the projected range R-p of oxygen, which correspond to the two interfaces of the BOX layer of the annealed samples. The heavily damaged region with hydrogen-induced defects appears to be the adsorption center for the outside oxygen to diffuse into the silicon during the high-temperature annealing process, and consequently, broaden the thickness of the BOX layer. The finding in the present work may provide a possible solution to reduce the cost of the conventional SIMOX-SOI wafers while maintaining a desirable BOX thickness.