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As is known high-intensity stationary thermal field emission electron sources needed for creation new high current electron probe devices for micro - and nanoelectronics applications: surface modification, depth profiling and dry etching, nanostructuring, X – ray “point” sources and X – ray lithography. In our work thermal field emission properties of nanoheterostructures (NHS) based on ZrO2/W<100>, ZrO2/W<111>, ZrO2/Mo<100> and ZrO2/Mo<111> metal film systems have been studied both experimentally and theoretically. Those systems represent ordered NHS arising as a result of forming a thin (about ~ 10 nm) crystalline dielectric ZrO2 film on the faceted tip surface of a refractory transition metal pointed (200 - 700 nm) microcrystal. The dielectric layer on the metal microcrystal surface was obtained by autoepitaxial growth of crystalline ZrO2 films under an intense thermal field acting the basic material of the systems studied. It has been found that the autoepitaxially grown NHS exhibit unique thermal field emission properties, namely, super high reduced brightness (up to ~ 1.0 E+06 A/(cm2 sr V) combined with high time stability of emission parameters at relatively low extracting field strength at the dielectric film surface (below ~ 5.0 E+05 V/cm). It has been shown that the emission properties of the NHS studied cannot be interpreted in terms of the existing concept of classical thermal field emission from the surface of homogeneous substances (metals or semiconductors). A theoretical model for the physical mechanism of thermal field emission from the surface of NHS of the metal (conductor) - thin dielectric film type was developed and justified. The proposed ideas of the mechanism of thermal field emission from the NHS surface allow one to consider the revealed anomalies in emission properties as typical features of a of new field emission process which was called the abnormal thermal field emission (ATFE). It should be noted that the concept of ATFE introduced permits adequate interpretation of well - known effects of so-called low-voltage field emission from the surface of diamond-like films and carbon nanotubes.
Work is maintained by grant RFBR No 05-08-33545_à.
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