Registration Number
0212U006375,
0110U006288
, R & D reports
Title
Research and development of regular arrays of silicon nanowires in dielectric matrix and resonant-tunneling structures
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Head
Evtukh Anatoli Antonovych,
Registration Date
23-03-2012
Organization
Institute of Semiconductor Physics of National Academy of Sciences of Ukrain
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A report is submitted in one volume, 50 pages, including figures 28, tables 6, 38 used sources. Keywords: electron field emission, silicon nanowires, technology, gas-transport reactions, the work function, the enhancement of the electric field, the effective area of emission. The purpose of Phase: Formation and study of the properties of ensembles of nanowires of silicon for electron field emission. The technologies of silicon nanowires formation by electrochemical etching of silicon and by chemical transport reactions have been developed. The results of investigations of electron field emission from porous silicon nanowires have been presented. As a result of research and development of the technology of Si nanowires formation in the process of electrochemical etching of silicon it was found that: - adding an oxidant in the electrolyte solution increases the electrode potential of silicon with respect to the electrolyte during the electrochemical etching due to galvanic anodization, which promotes the extraction of holes from the silicon ions in the oxidizing agent, so is more uniform etching of the surface. The roughness of por-Si films with increasing H2O2 concentration from 0.97 M to 2.5 M decreased almost twice (from 3.17 nm to 1.82 nm). In this case the size of large pores are the same, but their surface concentration is reduced; - at the same growth time of por-Si the emission properties of the resulting structures are improved with a decrease in the etching current density up to values of 1 mA/cm2. This is explained by the fact that at low current densities at anodization the porosity of surface is lower and, and larger nanocrystallites come to the surface, and they have good electrical contact with the substrate; The model for the calculation of the optical parameters of porous silicon with ellipsometric measurements has been proposed. In frame of the model has been shown that at increasing of etching time in conjunction with the deep etching of bulk silicon the etching of already formed surface nanocrystallites of por-Si is performed. The model of the energy band structure of silicon nanowire of por-Si and the calculated size of the individual nanocrystallites have been proposed. The results of the emission current-voltage characteristics are consistent with the AFM images, namely: the size of nanocrystallites is 1.5-2.8 nm. The work function = 3.5 eV, the effective area of emission = 2 x10E-15 cm2, the form factor = 5,54x10E9sm-1. As a result of research and development of the technology of Si nanowires formation by chemical transport reactions the following results have been obtained: - the technological regimes of growth of silicon nanostructures on semiconductor substrates have been defined. It was found that on a silicon substrate with a gold film of thickness d = 4-5 nm, and at value of the growth time t = 5 min. the precipitated crystals with an average diameter of ~ 50 - 60 nm and a height of about 100 - 200 nm have been deposited. The Increasing the growth time of nanoobjects into 2 times led to the emergence of large-diameter crystals of ~ 70 - 110 nm; - based on the studies of NC Si and Si1-xGeh by scanning and transmission electron microscopy it was shown that whisker is a heterostructure consisting of a crystalline core and nanoporous shell. The thickness of the nanoporous shells varies from 10 nm to 300 nm depending on the transverse diameter and the conditions of crystal growth. It is shown that the nanowires can be formed in the shells of two types: a) with a smooth surface and small pore size and wall between pores 0.4 nm and b) with rough surface on which the pore sizes vary from 3 to 5 nm. The formation of a certain type of shell is determined by the flow of adatoms on the surface of the crystal JS and flow due to diffusion along the lateral wall of the crystal, JD. If JS<JD the nanoporous shell of the first type is formed and at JS> JD, the nanoporous shell of the second type is formed.
Product Description
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Євтух Анатолій Антонович
Братусь Олег Леонідович
Кизяк Анатолій Юрійович
Литовченко Володимир Григорович
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2020-04-02
