Nanoscale potential barrier distributions and their effect on current transport in Ni/n type Si Schottky diode

M. Yeganeh; N. Balkanian; Sh. Rahmatallahpur

doi:10.1088/1674-4926/36/12/124001

J. Semicond. > 2015, Volume 36 > Issue 12 > 124001, doi: 10.1088/1674-4926/36/12/124001

SEMICONDUCTOR DEVICES

Nanoscale potential barrier distributions and their effect on current transport in Ni/n type Si Schottky diode

M. Yeganeh, N. Balkanian and Sh. Rahmatallahpur

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Corresponding author: M. Yeganeh,Email:

Abstract: We have experimentally studied the Ni/n-Si nano Schottky barrier height(SBH) and potential difference between patches in the nano Schottky diodes(SD) using contact atomic force microscopy(C-AFM) in tapping mode and scanning tunneling microscopy(STM). Topology measurement of the surface with C-AFM showed that, a single Ni/n-Si SD consists of many patches with different sizes. These patches are sets of parallel diodes and electrically interacting contacts of 5 to 50 nm sizes and between these individual diodes, there exists an additional electric field. In real metal semiconductor contacts(MSC), patches with quite different configurations, various geometrical sizes and local work functions were randomly distributed on the surface of the metal. The direction and intensity of the additional electric field are distributed in homogenously along the contact metal surface. SBH controls the electronic transport across the MS interface and therefore, is of vital importance to the successful operation of semiconductor devices.

Key words: nano Schottky diode, additional electrical field, nanopatch, STM and C-AFM

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Fig. 1. 1. (a) Schematic diagrams of inhomogeneous surface (surfaces containing various micro and nano crystals. (b) Various local work functions. (c) Local surface work functions along ox axis. (d) Electric spot field E_f. (e) Average work functions in eV.

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Fig. 2. Experimental set up for surface measurements and device I –V characterizations.

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Fig. 3. (Color online) (a) C-AFM topology image ofthe Si surface after the cleaning. (b) The surface potential distribution of the same surface.

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Fig. 4. (Color online) (a) The morphology of nickel layer surface coated on n-Si. (b) Current passing from the surface. (c) Changes in the surface work function along the line.

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Fig. 5. (Color online) (a) Image of current transport through contact patches in 0.5 V forward bias. (b) Magnified image of the amount of current transport in the selected areas with different colors in Figure 5(a).

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