Electronic Properties of Porous Silicon

1994 ◽  
Vol 358 ◽  
Author(s):  
M. R. Beltran ◽  
J. Tagüeña-Martinez ◽  
M. Cruz ◽  
C. Wang
Keyword(s):  
Porous Silicon ◽  
Band Gap ◽  
Tight Binding ◽  
Perfect Crystal ◽  
Energy Band Structure ◽  
Basis Set ◽  
Pore Morphology ◽  
Hydrogen Atoms ◽  
Direct Band Gap ◽  
Direct Band

ABSTRACTPorous silicon (PS) has been extensively studied in recent years. The origin of its luminescence has been a subject of debate. This work attempts to give some insight towards the understanding of this phenomenon, studying the behaviour of the energy band structure of PS as a function of the pore morphology and distribution, for a given porosity. The porous structure is modeled as empty columns of different sizes and shapes, produced into san otherwise silicon perfect crystal. The columns are passivated with hydrogen atoms. A tight-binding Hamiltonian on an ; sp3:s* basis set is applied onto a supercell. Due to the simplicity of the model, morphology effects can be analyzed. The results show that the band :gap and the nature of the 'States at the top of the valence band depend on the morphology. Furthermore, we also discuss the shift of the conduction band minimum towards the gamma point, producing an almost direct band gap, as the pore distribution changes.

Computation of the Porous Silicon Dielectric Function in the Supercell Model and Comparison with Experiment

1999 ◽  
Vol 579 ◽  
Author(s):  
J. Tagüeeña-Martínez ◽  
Y.G. Rubo ◽  
M. Beltrán ◽  
C. Wang ◽  
M. Cruz
Keyword(s):  
Porous Silicon ◽  
Dielectric Function ◽  
Imaginary Part ◽  
Absorption Edge ◽  
Tight Binding ◽  
Pore Morphology ◽  
Hydrogen Atoms ◽  
Comparison With Experiment ◽  
Supercell Model

ABSTRACTWe present the results for the imaginary part of the dielectric function of porous silicon, which were obtained with the tight-binding 128–atom supercell model for different porosities. The supercells have been chosen to allow the interconnection of the Si skeleton. We have analyzed also the effects of pore morphology. We have found that, at a fixed porosity, the developing of the surface, resulting in the increase of saturating hydrogen atoms, leads to a noticeable blueshift of the absorption edge.

A Microscopic Model for the Dielectric Function of Porous Silicon

1996 ◽  
Vol 452 ◽  
Author(s):  
M. Cruz ◽  
M. R. Beltran ◽  
C. Wang ◽  
J. Tagüeña-Martinez
Keyword(s):  
Porous Silicon ◽  
Dielectric Function ◽  
Tight Binding ◽  
Microscopic Analysis ◽  
Basis Set ◽  
Hydrogen Atoms ◽  
Nano Structures ◽  
Materials Research ◽  
Si Films ◽  
Supercell Model

AbstractMicro and nano-structures have opened a new area in materials research since they present interesting phenomena such as efficient luminescence and localization of carriers. An important example of these new materials is porous silicon (PS). It is considered that the quantum confinement is an essential cause of the opto-electronic properties of PS [1], thus microscopic analysis should be performed. We have developed a supercell model to study PS with a tight-binding Hamiltonian, where an sp3s* basis set is used. In an otherwise perfect silicon structure empty columns of atoms are produced and passivated with hydrogen atoms [2]. In this work we calculate the dielectric function and compare it against experimental data for bulk c-Si, ultrathin c-Si films and PS. We discuss the importance of considering the relaxation of the electron wavevector (k) conservation in order to include disorder effects in PS.

Optical Studies of Poly (N-Carbazole) (PVK) Blending with Polyvinylpyrrolidone (PVP) Using Tauc/Davis-Mott Model

2013 ◽  
Vol 652-654 ◽  
pp. 527-531 ◽  
Author(s):  
A.N. Alias ◽  
T.I. Tunku Kudin ◽  
Z.M. Zabidi ◽  
M.K. Harun ◽  
Ab Malik Marwan Ali ◽  
...  
Keyword(s):  
Band Gap ◽  
Urbach Energy ◽  
Quartz Substrate ◽  
Optical Studies ◽  
Direct Band Gap ◽  
Mott Model ◽  
Blended Polymer ◽  
Electronic Parameters ◽  
Direct Band ◽  
Indirect Band Gap

The optical absorption spectra of blended poly (N-carbazole) (PVK) with polyvinylpyrrolidone (PVP) in various compositions are investigated. A doctor blade technique was used to coat the blended polymer on a quartz substrate. The electronic parameters such as absorption edge (Ee), allowed direct band gap (Ed), allowed indirect band gap (Ei), Urbach edge (Eu) and steepness parameter (γ) were calculated using Tauc/Davis-Mott Model. The results reveal that the Ee, Ed and Ei increase with increasing of PVP ratio. There also have variation changing in Urbach energy and steepness parameter.

Theoretical Derivations of a Direct Band Gap Semiconductor of SiC Doped with Ge

2014 ◽  
Vol 44 (1) ◽  
pp. 167-176 ◽  
Author(s):  
Adit Ghosh ◽  
Chandrika Varadachari
Keyword(s):  
Band Gap ◽  
Direct Band Gap ◽  
Direct Band

Atomically Thin Arsenene and Antimonene: Semimetal-Semiconductor and Indirect-Direct Band-Gap Transitions

2015 ◽  
Vol 54 (10) ◽  
pp. 3112-3115 ◽  
Author(s):  
Shengli Zhang ◽  
Zhong Yan ◽  
Yafei Li ◽  
Zhongfang Chen ◽  
Haibo Zeng
Keyword(s):  
Band Gap ◽  
Direct Band Gap ◽  
Direct Band

Strain-induced semimetal-to-semiconductor transition and indirect-to-direct band gap transition in monolayer 1T-TiS2

RSC Advances ◽  
2015 ◽  
Vol 5 (102) ◽  
pp. 83876-83879 ◽  
Author(s):  
Chengyong Xu ◽  
Paul A. Brown ◽  
Kevin L. Shuford
Keyword(s):  
Band Gap ◽  
Electronic Properties ◽  
Plane Strain ◽  
Material Properties ◽  
First Principles ◽  
Tensile Strain ◽  
First Principles Calculations ◽  
Direct Band Gap ◽  
Direct Band ◽  
Uniform Plane

We have investigated the effect of uniform plane strain on the electronic properties of monolayer 1T-TiS2using first-principles calculations. With the appropriate tensile strain, the material properties can be transformed from a semimetal to a direct band gap semiconductor.

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