Negative Magnetoresistance in Si Nanograting Layers

Tavkhelidze, A.; Grabecki, G.; Jangidze, Larissa; Yahniuk, Ivan; Taliashvili, Zakhari; Taliashvili, B.

doi:10.1002/pssa.201800693

Cited by 10 publications

(10 citation statements)

References 21 publications

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“…Thermopower measurements demonstrate that the NG islands are n-type. Transport measurements (resistivity and Hall coefficient) confirm that they are n-type and resistivity decreases at low temperatures [19,20]. These results are in agreement with G-doping theory.…”

Section: Sample Preparation and Characterizationsupporting

confidence: 85%

Optical and electronic properties of periodic Si nanostructures

Tavkhelidze

Bayramov

Aliyeva

et al. 2017

Phys. Status Solidi C

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Nanogratings (NGs) on the surface of the top Si layer of a Si/SiO2/ substrate device structure were prepared using laser interference lithography. Electron transport, photoluminescence, and Raman scattering were then studied on the plain Si and NG Si structures to see the effect of NG introduction. As a result of NG‐introduction and very likely G‐doping maintenance, all samples studied in this work displayed a 2 to 3 order of magnitude reduction in resistivity for NG Si. The Hall coefficient indicated that electrons are main charge carriers that is also expected for exactly G‐doping. Plain Si layer did not show any photoluminescence either for 532 nm (2.38 eV) or 325 nm (3.81 eV) laser excitation. A broad photoluminescence band, composed of a number of almost equidistant peaks was observed on NG Si layer between the photon energies 1.5 and 3.5 eV. Both Stocks and anti‐Stocks components for 522.65 cm−1 phonons at room temperature were observed in the Raman spectra of NG Si layer. Estimated from the ratio between the intensities of Stocks and anti‐Stocks components, the drop (if any) in phonon gas temperature below ambient (295 K) does not exceed 3 K.

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Section: Sample Preparation and Characterizationsupporting

confidence: 85%

Optical and electronic properties of periodic Si nanostructures

Tavkhelidze

Bayramov

Aliyeva

et al. 2017

Phys. Status Solidi C

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“…A coherent laser with a wavelength of 375 nm and a Lloyd interferometer were used for the interference lithography. The reactive ion etching of Si was performed using CF 4 , as described in [ 5 , 13 ]. The reactive ion etching time was adjusted to 35 s to achieve an indent depth of 10 nm ( Figure 3 a).…”

Section: Methodsmentioning

confidence: 99%

“…The indent depth was monitored by scanning a plain area (adjacent to the NG layer) using a profile meter. The cross-section of the NG layer was sinusoidal (see Figure 1 of [ 13 ]), which is characteristic of NG layers prepared by laser interference lithography. Finally, a metal was deposited on the back side of the chip to achieve ohmic contact: Al was deposited on the p-type and p + -type substrates by thermal evaporation and Ti/Ag was deposited on the n-type and n + -type silicon substrates by magnetron sputtering, as described in [ 24 ].…”

Section: Methodsmentioning

confidence: 99%

“…The latest developments in nanotechnology have allowed the fabrication of low-dimensional periodic nanostructures [ 1 , 2 , 3 ], including nanogratings (NGs). Imposed periodic nanostructures such as NG layers are known to significantly affect the electronic [ 4 , 5 ], thermoelectric [ 6 , 7 ], optical [ 8 , 9 ], electron emission [ 10 , 11 ], and magnetic [ 12 , 13 ] properties of semiconductors when the NG depth becomes comparable to the de Broglie wavelength. This can be attributed to the special boundary conditions enforced by the NG on the wave function.…”

Section: Introductionmentioning

confidence: 99%

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Fermi-Level Tuning of G-Doped Layers

Tavkhelidze¹,

Bibilashvili²,

Jangidze³

et al. 2021

Nanomaterials

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Recently, geometry-induced quantum effects were observed in periodic nanostructures. Nanograting (NG) geometry significantly affects the electronic, magnetic, and optical properties of semiconductor layers. Silicon NG layers exhibit geometry-induced doping. In this study, G-doped junctions were fabricated and characterized and the Fermi-level tuning of the G-doped layers by changing the NG depth was investigated. Samples with various indent depths were fabricated using laser interference lithography and a consecutive series of reactive ion etching. Four adjacent areas with NG depths of 10, 20, 30, and 40 nm were prepared on the same chip. A Kelvin probe was used to map the work function and determine the Fermi level of the samples. The G-doping-induced Fermi-level increase was recorded for eight sample sets cut separately from p-, n-, p+-, and n+-type silicon substrates. The maximum increase in the Fermi level was observed at a10 nm depth, and this decreased with increasing indent depth in the p- and n-type substrates. Particularly, this reduction was more pronounced in the p-type substrates. However, the Fermi-level increase in the n+- and p+-type substrates was negligible. The obtained results are explained using the G-doping theory and G-doped layer formation mechanism introduced in previous works.

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“…Current developments in nanotechnology have enabled patterning the surface of semiconductor layers by nanoscale gratings with periodical arrays of width smaller than 1 µm [1][2][3][4]. Nanograting (NG) patterns have been shown to dramatically change the electronic [5][6][7], magnetic [8,9], optical [10][11][12][13][14], and electron emission [15,16] properties of the semiconductor substrate when the grating depth becomes comparable with de Broglie wavelength of electrons. This can be attributed to the special boundary conditions enforced by the NG on the wave function.…”

Section: Introductionmentioning

confidence: 99%

G-Doping-Based Metal-Semiconductor Junction

Tavkhelidze

Jangidze

Taliashvili³

et al. 2021

Coatings

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Geometry-induced doping (G-doping) has been realized in semiconductors nanograting layers. G-doping-based p-p(v) junction has been fabricated and demonstrated with extremely low forward voltage and reduced reverse current. The formation mechanism of p-p(v) junction has been proposed. To obtain G-doping, the surfaces of p-type and p+-type silicon substrates were patterned with nanograting indents of depth d = 30 nm. The Ti/Ag contacts were deposited on top of G-doped layers to form metal-semiconductor junctions. The two-probe method has been used to record the I–V characteristics and the four-probe method has been deployed to exclude the contribution of metal-semiconductor interface. The collected data show a considerably lower reverse current in p-type substrates with nanograting pattern. In the case of p+-type substrate, nanograting reduced the reverse current dramatically (by 1–2 orders of magnitude). However, the forward currents are not affected in both substrates. We explained these unusual I–V characteristics with G-doping theory and p-p(v) junction formation mechanism. The decrease of reverse current is explained by the drop of carrier generation rate which resulted from reduced density of quantum states within the G-doped region. Analysis of energy-band diagrams suggested that the magnitude of reverse current reduction depends on the relationship between G-doping depth and depletion width.

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Negative Magnetoresistance in Si Nanograting Layers

Cited by 10 publications

References 21 publications

Optical and electronic properties of periodic Si nanostructures

Optical and electronic properties of periodic Si nanostructures

Fermi-Level Tuning of G-Doped Layers

G-Doping-Based Metal-Semiconductor Junction

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