Aluminum thin films were photodeposited on silicon wafer from dimethyl-aluminum hydride under illumination of the ultraviolet photons generated by a deuterium lamp with a distinguished wavelength dependence. Namely, the growth rates increase linearly with vapor pressure under illumination of the l60-nm vacuum ultraviolet band from the lamp, while the growth starts above 0.3 mTorr only with the 240-nm band. To study the early stage of photo-deposition of Al, we constructed a scanning tunneling microscope and observed Al, islands. Steep sides were observed on islands with the distinguished boundary between vertical and horizontal growth. The shape of islands formed in the illuminated region and in the dark area was identical, thus indicating the absence of photo-induced migration effects.