Atomic force microscopy is employed in the experimental study of specific features of the field emission of electrons from a single silicon needle-type cathode to quasi-vacuum (air). Noncontact regime of the atomic force microscopy is used to measure the I–V characteristics of a single cathode with nanometer-scale tip radius at distances of 10 and 20 nm between the cathode tip and the measurement probe. Electric field distributions are simulated for both surface of the tip of a single cathode and tip surfaces of single cathodes in an array, and the results are used to theoretically estimate electric field enhancement versus cathode–probe distance. It is shown that the enhancement factor calculated from the experimental I–V characteristics in the Fowler–Nordheim coordinates is greater than the result of theoretical calculations by several orders of magnitude. This circumstance indicates that additional quantum dimensional effects that play an important role in the generation of the electron emission current in the nanoscale gap must be taken into account.