Geometry‐induced quantum effects in periodic nanostructures

Abstract

Recently, geometry-induced quantum effects in periodic nanostructures were introduced and observed. Nanograting has been shown to dramatically improve thermoelectric and electron emission properties, and originate a geometry induced doping or G-doping. Here, we concentrate on experimental investigation of G-doping. We fabricate nanograting (NG) layers and measure their electron transport properties. The grating was fabricated on the surface of a silicon on insulator (SOI) wafer device layer using laser interference lithography followed by reactive ion etching. Next, large square islands were shaped in the device layer.The characteristics of NG and plain islands were compared to investigate G-doping. Resistivity temperature dependences were recorded in the range of 4-300 K. For all 21 samples, the NG layers show a 2-3 order of magnitude reduction in resistivity with respect to the plain layer. Hall coefficient and thermopower measurements demonstrate that the NG layers are n-type. Obtained G-doping level corresponded to an "effective impurity" concentration of 10 18 cm À3 . The dependence of the resistivity and Hall coefficient on temperature and magnetic field were recorded in the ranges of 2-300 K and 0-3 T, respectively.

Optical and electronic properties of periodic Si nanostructures

“…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.…”

Negative Magnetoresistance in Si Nanograting Layers

“…We have shown that in Si NGs with small periods, temperature dependences of resistivity and Hall coefficient show metallic behavior, indicating that the Fermi level is placed within the conduction band. Ellipsometry measurements also confirmed that dielectric function is of metallic type .…”

“…The NG structure (Figure a) was defined at the center of a large 8 × 10 mm SOI layer using laser interference lithography with subsequent reactive ion etching, in the same way as described in ref. . The depth of the NG trenches were measured at the specially designed reference step made on the same SOI layer, near the NG.…”

“…Present developments in nanotechnology enable patterning of semiconductor layers in to gratings with periods much smaller than 1 μm . In our previous works, we have made such structures in Si layers . We have shown that these so‐called nanogratings (NGs) exhibit strongly modified electronic, thermoelectric, optical, and electron emission properties, if their sizes becomes comparable to de Broglie wavelength of electrons.…”

“…In our previous works, we have made such structures in Si layers . We have shown that these so‐called nanogratings (NGs) exhibit strongly modified electronic, thermoelectric, optical, and electron emission properties, if their sizes becomes comparable to de Broglie wavelength of electrons. We have developed a model in which the boundary conditions imposed by a NG on the electron wave functions cause certain quantum states to be forbidden, and their density becomes reduced .…”