Geometry-induced electron doping in periodic semiconductor nanostructures

Abstract

Recently, new quantum features have been observed and studied in the area of nanostructured layers. Nanograting on the surface of the thin layer imposes additional boundary conditions on the electron wave function and induces G-doping or geometry doping. Gdoping is equivalent to donor doping from the point of view of the increase in electron concentration n. However, there are no ionized impurities. This preserves charge carrier scattering to the intrinsic semiconductor level and increases carrier mobility with respect to the donor-doped layer. G-doping involves electron confinement to the nanograting layer. Here, we investigate the system of multiple nanograting layers forming a series of hetero-or homojunctions. The system includes main and barrier layers. In the case of heterojunctions, both types of layers were G-doped. In the case of homojunctions, main layers were G-doped and barrier layers were donor-doped. In such systems, the dependence of n on layer geometry and material parameters was analysed. Si and GaAs homojunctions and GaAs/AlGaAs, Si/SiGe, GaInP/AlGAs, and InP/InAlAs heterojunctions were studied. G-doping levels of 10 18 -10 19 cm -3 were obtained in homojunctions and type II heterojunctions. High G-doping levels were attained only when the difference between band gap values was low.

Negative Magnetoresistance in Si Nanograting Layers

“…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.…”

Optical and electronic properties of periodic Si nanostructures

“…Thus, NG introduction profoundly changes photoluminescence properties of Si above the energy gap. In the light of the works by Tavkhelidze et al [5][6][7][8] the observed changes can plausibly be explained by G-doping effect. At the same time, along with metallization due to G-doping, involvement of surface plasmons or, more exactly, plasmon polaritons is possible and can additionally be considered to account for the observed photoluminescence emerging above the energy gap of Si.…”

“…We used saturated value of the ratio to estimate phonon gas temperature that is found from the relation I aÀst =I St ¼ expðÀ hv=K B TÞ [18]. According to our estimations, the drop (if any) in the temperature of phonons, expected in the case of G-doping [5] does not exceed 3 K below the ambient temperature (3K). However, more Raman observations, especially for Raman spectra taken with excitation energies from transparency region of Si (i.e., below the energy gap) are necessary to come to a definite conclusion.…”

“…1 Introduction Resent developments in nanotechnology have enabled the fabrication of small size periodic structures [1][2][3][4]. One of such structures, namely nanograting (NG) layers have been shown to dramatically change the electronic [5], thermoelectric [6], and electron emission properties [7] when the grating dimensions become comparable with the de Broglie wavelength. This is due to the additional boundary conditions imposed by a NG on the wave function.…”

Spectroscopic planar diffraction ellipsometry of Si‐based multilayer structure with subwavelength grating

“…1 Introduction Noticeable metallization of semiconductor thin layers with nano-grating has recently been disclosed and accounted for the increased number of conduction electrons due to depression of the occupied quantum states in the systems with nano-grating [1,2]. It is important to mention that above increase in conduction electron concentration, or so-called geometry-induced doping (G-doping) results from re-arrangement in electron eigenstates.…”