We report the low temperature growth of ultrathin SiO2 films on crystalline Si by photo-oxidation with an array of Xe-2* excimer vacuum ultraviolet (VUV) lamps operating at a wavelength of 172 nm. Ultrathin layers from 1.2 to 3.3 nm thickness were grown at time intervals from 5 to 40 min at 100-400 degreesC at an O-2 pressure of 1000 mbar. Growth rates of up to 0.2 nm min(-1) have been achieved at 400 degreesC, while the chemical bonding of the films has been analysed by Fourier transform infrared (FTIR) spectroscopy and found to be SiO2. The as-grown 3.3 nm films exhibited good dielectric properties, comparible to SiO2 films of identical thickness, grown by RTP at 800 degreesC.