The energy distributions of field-emitted electrons from single-tip n type and p type Si field emitters have been analyzed. The energy distributions of both n type and p type Si emitters show a single peak, and the peak position shifts slightly towards the low energy side in the n type emitter as the gate voltage is increased. In the case of the p type emitter a considerably larger shift towards lower energies is observed. The distributions from the n type emitter have the same threshold energies near the Fermi level energy and become broader with the increase in the gate voltage. On the other hand, the threshold energies of the p type emitter are more than 1.5 eV below the Fermi level and shift to the lower energy side as well as the peak position in the energy distribution with increasing the gate voltage. In addition, the energy distributions of the p type emitter are considerably broad in comparison with those of the n type emitter, but the full width half maximums (FWHMs) of the distributions do not significantly change with the increase in the gate voltage. These results suggest that for the n type Si field emitter electrons are basically supplied from the Si conduction band and are emitted from the neighborhood of the conduction band under the effect of the band bending and electron trapping in surface and oxide states at the interfaces of the emitter. On the other hand, for the p type Si field emitter, electrons are mainly emitted through the interface states supplied from the valence band of Si. (c) 2005 American Vacuum Society.