The technology of nanostructure formation by laser radiation on Si surface for the electron field emitter is proposed. n-type Si wafers are used in the experiments. The nanometer size, conelike nanostructures with nanosphere on top of the cone were created on the surface as a result of laser irradiation. The electron field emission from such nanostructures has been investigated. It has some peculiarities, namely, (i) a decrease in the threshold field in subsequent measurements and (ii) two slopes of Fowler-Nordheim curves (higher slope at low fields and lower slope at high fields). Analysis of the scanning electron microscopy micrographs and electron field emission curves allows the authors to estimate (i) the electron field enhancement coefficient, beta approximate to 100, (ii) work functions, Phi(1)=6.8 eV at the first measurement and from the two slopes in subsequent measurements Phi(2)=3.9 eV, Phi(3)=2.38 eV, and (iii) the effective emission area, alpha=(3x10(-8))-(1.8x10(-5)) cm(2). The experimental results obtained have been explained in frame of the proposed model which takes into account formation of native oxide and/or positive dipoles (Si+-O-) due to oxygen adsorption on the Si surface.