Nanostructured SiC as a promising material for the cold electron emitters

Goriachko, A.; Стріха, М. В.

doi:10.15407/spqeo24.04.355

Cited by 3 publications

(3 citation statements)

References 15 publications

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“…Тому для емісії з наноаркушу напівпровідника ZnO скористаємося з модифікації формули, виведеної в [10] для випадку, зображеного на рис. 2: різкий вигин зон у матеріалі n-типу під впливом прикладеного зовнішнього поля утворює приповерхневу 2D квантову яму, у якій зосереджені електрони:…”

Section: рис 1 структура емісійної поверхні катоду з наноаркушів Zno ...unclassified

ON THE PHYSICAL NATURE OF FIELD EMISSION FROM ZnO NANOSHEETS

Strikha,

Khilinich

2024

Sens. elektron. mìkrosist. tehnol.

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The performed analysis allows us to determine the physical nature of the field emission process from ZnO nanosheets. It is shown that the possible range of effective values of the work function at the top of the nanosheet corresponds to the field enhancement factor β of the order of 20000. Such values of β and a nanosheet height of the order of μm correspond to subnanometer values of the radius of the nanosheet top, which is in good agreement with the experimentally known fact that the field emission from the nanostructured surface almost all comes from the top few atoms of the nanoprotrusion. Thus, the effective emission occurs only from a very small part of the total cathode surface, but the large value of the field enhancement factor β provides a noticeable emission current density of the order of magnitude of 3∙10-4 А/m2 for a turn on field of the order of magnitude of 3∙106 V/m.

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Section: рис 1 структура емісійної поверхні катоду з наноаркушів Zno ...unclassified

ON THE PHYSICAL NATURE OF FIELD EMISSION FROM ZnO NANOSHEETS

Strikha,

Khilinich

2024

Sens. elektron. mìkrosist. tehnol.

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“…From the same viewpoint, we may expect the appearance of effective devices based on silicon carbide 𝛽-SiC (𝐸 𝑔 = 2.5 eV, 𝑋 𝑜 = 2 eV). The creation of promising cathodes on its basis for the field emission has already been reported [33].…”

Section: Theoretical Model To Describe the Reduction Of Work Function...mentioning

confidence: 99%

Surfaces with Lowered Electron Work Function: Problems of Their Creation and Theoretical Description. A Review

Strikha,

Goriachko

2023

Ukr. J. Phys.

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Experimental studies devoted to the creation of the modern photocathodes or efficient field emission cathodes with lowered work function or low/negative electron affinity are reviewed. We present theoretical models, where the electron affinity lowering is associated with the influence of electrically charged layers at the semiconductor/insulator interface. Modern experimental techniques of measuring the work function or the electron affinity and technologies aimed at fabricating the surfaces with low work function/electron affinity are described. In the framework of a simple theoretical model developed by the authors, it has been demonstrated that the presence of a dipole layer (e.g., composed of negatively charged oxygen ions and positively charged rare earth ions) at the semiconductor surface can lower the electron affinity by up to 3 eV provided equal concentrations of oppositely charged adsorbate ions. It is also shown that if the surface concentration of negatively charged oxygen ions is higher than the surface concentration of positively charged metal ions, the lowering of the electron affinity becomes smaller due to the upward band bending in the space charge region in the semiconductor; otherwise, the lowering of the electron affinity becomes larger due to the downward band bending. This effect allows technological proposals to be formulated for obtaining surfaces with minimum work function values in modern field-emission-based electronic devices. In the framework of the proposed model, the work function was evaluated for the OH-functionalized MXene. The corresponding value for the unfunctionalized MXene equals about 4.5 eV, being practically independent of the number of Ti and C layers (from 1 to 9 layers). The OH-functionalization lowers it down to about 1.6 eV, and this value is also practically independent of the number of atomic layers in MXene. Experimental approaches to obtain cathodes with low work function/low electron affinity are described. They are aimed at creating a spatial separation of electric charges in the near-surface cathode region perpendicularly to the surface plane. The corresponding spatial distributions of positive and negative charges are characterized by their localization either in two different atomic planes or in one plane and an extended space region (the latter variant is typical of semiconductor substrates). The technologies for producing such surfaces are based on various methods of adsorbate deposition onto the metal or semiconductor substrate: physical vapor deposition, chemical vapor deposition, liquid phase deposition, diffusion from the substrate bulk, and so forth. Particular attention is paid to the experimental works dealing with the adsorbtion of rare earth metals (Ce, Gd, Eu) and the coadsorbtion of oxygen onto the Si, Ge, and Mo surfaces (in a nano-structured state as well), which results in the dipole layer formation and the work function reduction.

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“…Останній доданок у правій частині (10) легко оцінити з формули плоского конденсатора: ) ), для якого вже повідомлено про створення перспективних катодів для польової емісії [7].…”

Section: рис 2 виникнення від'ємної спорідненості х unclassified

A Theoretical Model for Description of Work Function Lowering for Semiconductor / Insulator Under the Influence of the Charged Bilayer in the Surface Region

Strikha¹,

Goriachko²

2022

SEMST

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We develop a simple theoretical model, connecting a lowering of the electron affinity of a semiconductor (or insulator) with such parameters as the density of surface charge, localized on surface states or adsorbed atoms, and the volume density of charge within the space charge region, both of which form a charged bilayer on the surface. Our model allows to estimate the perspectiveness of various materials as films for creating modern photocathodes or effective field emission cathodes with substantially lowered or zero work function.

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Nanostructured SiC as a promising material for the cold electron emitters

Cited by 3 publications

References 15 publications

ON THE PHYSICAL NATURE OF FIELD EMISSION FROM ZnO NANOSHEETS

ON THE PHYSICAL NATURE OF FIELD EMISSION FROM ZnO NANOSHEETS

Surfaces with Lowered Electron Work Function: Problems of Their Creation and Theoretical Description. A Review

A Theoretical Model for Description of Work Function Lowering for Semiconductor / Insulator Under the Influence of the Charged Bilayer in the Surface Region

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