THERMAL FIELD ELECTRON EMISSION FROM THE LOW DIMENSIONAL NANOSTRUCTURE SURFACES
The short review of existing representations on the physical mechanism of a "low-voltage" field electron emission from a surface of various low dimensional nanostructures (NS): microcrystals of high gap semiconductors, carbon nanotubes and diamond like films was made. The offered models were found to be unable to give adequate interpretation to the results obtained earlier in examinations of a "low-voltage" field emission. To elucidate physical mechanism of "low-voltage" field electron emission original nanotechnology for the formations of nanoheterostructures (NHS), formed by a thin (~5-10 nm) layer of dielectric (ZrO<sub>2</sub>) on the surface of point microcrystals W was developed. Examination of field emission properties ZrO<sub>2</sub>/W NHS was performed. It was found, that at substance temperature ~1900 K <<i>T</i> <~2100 K ZrO<sub>2</sub>/W NHS is characterized by abnormally high reduced luminosity (to ~10<sup>10</sup> A/(m<sup>2</sup>∙sr∙V)) and high stability of field emission properties. It was shown, that excitation of a thermal field emission from the surface of ZrO<sub>2</sub>/W NSH occurs at a rather low values (less than 50 V/μm) of field intensity. Functional dependence of emission current density on field intensity on the surface of NHS studied was shown not to coincide with the conventional theory of the phenomenon of thermal field emission of electrons from the surface of homogeneous substances (metals and electron semiconductors). The performed experiments suggest that irrespective of structural features of a substance and NS morphology the mechanism of the phenomenon of a "low-voltage" field emission from NHS surface of various dimensionality is due to the processes of formation in the sub-surface layer of nanostructure of the bound spatial positive charge. The unique thermal field emission properties of NHS studied can be used both for creation high-intensity "low-voltage" sources of electrons and highly effective systems of transformation of thermal energy in electrical energy.