R.K. Yafarov – Dr. Sc. (Eng.), Professor, Saratov branch of Kotel\'nikov IRE of RAS
S.Yu. Suzdaltsev – Ph. D. (Eng.), Saratov branch of Kotel\'nikov IRE of RAS
V.Ya. Shanygin – Ph. D. (Eng.), Research Scientist, Saratov branch of Kotel\'nikov IRE of RAS
Influence of plasmochemical modification of a surface on field emission properties of crystals of silicon of various types of conductivity is revealed experimentally and proved theoretically. It is shown that plasmochemical etching of plates of silicon in high-ionized microwave plasma with use of various chemically active gas environments allows to operate over a wide range a threshold of intensity of electric field at which field emission of electrons, and the maximum density of field emission currents begins.
It is established what by the main factor which reduces the maximum density of field emission currents and is determined by a threshold of intensity of the field of field emission of electrons on crystals of silicon of various types of conductivity is natural oxide of silicon. Especially important it for field emission from p type silicon plates. Use of chemically active gas environments for removal of a dielectric layer of a natural oxide covering and plasmochemical modification of superficial phases of crystals of silicon allows reducing a potential barrier and almost much to increase the maximum density of field emission currents. It is provided as a result of complex impact on processes of formation of the built-in near-surface potentials, change of the total dipolar moment and a superficial charge which lead to enrichment or impoverishment of blankets the main carriers, passivation of the emitting surface at the expense of a chemosorption of elements with a strong chemical bond. As a result of total influence of these factors the threshold of the beginning of field emission on silicon р type can be significantly lower and the maximum density of currents is higher, than on silicon crystals n type. Removal of an oxide covering from emitters on silicon plate’s n type increases a threshold of intensity of the field and, at the same time, doesn\'t reduce, and increases the maximum density of field emission currents. Thus, at modification of properties of a surface with use of plasmochemical processing increase in a threshold of intensity of the field of field emission doesn\'t involve, as a rule, automatic reduction of density of the maximum field emission currents. These results meet modern quantum-mechanical expectations according to which sizes of field emission currents are defined not only transparency of potential barriers, but also density of states and concentration of electrons in the semiconductor. Therefore density of the maximum field emission currents from p type semiconductors at which field emission is carried out from a valence band can exceed considerably the maximum density of field emission currents from silicon with electronic type of conductivity. The last is caused by the fact that density of states in a valence band of semiconductors is higher, than in a conductivity zone.
Results of the executed research expand possibilities of use of crystals of silicon during creation on their basis of various radiation re-sistant functional devices and micro devices.
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