Electron states and luminescence transition in porous silicon

Abstract

The theoretical analysis of two different Si wires of size 5×4 and 3×4, simulating porous Si, has been performed through the linear-muffin-tin-orbitals method in the atomic sphere approximation. All the atomic core energies were self-consistently computed and used to directly compare the energies of the quantum wires and that of the crystalline Si, by aligning the 2p core level of a Si atom located at the center of the wire to that corresponding to crystalline Si. The optical properties of the wires have been computed by evaluating the imaginary part of the dielectric function. The main results are (i) the opening of the gap is asymmetric; 1/3 of the widening is in the valence band, while 2/3 in the conduction band; (ii) the near band-gap states originate mainly from Si atoms located at the center of the wire; (iii) the imaginary part of the dielectric function shows a low-energy structure, strongly anisotropic, that follows the blueshift for the gap and is identified as responsible of the luminescence transition; (iv) the spatial localization of the valence- and conduction-band states participating in the luminescence transition shows that all the Si atoms of the wire are collectively involved

Size dependence of nanostructures: Impact of bond order deficiency

“…(b) The E PL blueshift of nano-Si. Data-1 [458], data-2 [516], data-3 [509], data-4 [517], data-5 [518], data-6 [519], data-7 [520], and data-8 [515] are calculation results. Data-9 [515], data-10 [513], data-11 [478], data-12 [521], and data-13 [45] are measurements.…”

Oxidation electronics: bond–band–barrier correlation and its applications

“…Data 1-13 are after Refs. [468][469][470][471][472][473][474][475][476][477][478][479][480]. applied, respectively, to the first two atomic layers of a spherical dot.…”

Well width‐dependent electron Raman scattering in ZnS/CdSe cylindrical quantum dot quantum well

“…This is caused by a high anisotropic optical activity due to quantum confinement. 27,28 As the radii decrease, the anisotropic optical activity becomes stronger due to more significant quantum confinement, Figure 6. Raman spectrum of the ZnS/CdSe cylindrical QDQW in the scattering configuration X E e l , E e sz X with various radii.…”

“…The emission spectrum for different sizes of QDQW reveals the anisotropic optical activity due to quantum confinement of this system. 27,28 The spectrum we obtained here could be used to study the electron band structure of such system.…”

“…Anisotropic optical properties in low-dimensional semiconductors has been found. 27,28 Dielectric and quantum confinement effects result in prominent exciton features such as large binding energies and oscillator strengths. 29 In our study, we find that the quantum confinement effects can also intensify the DCS of Raman scattering.…”