Absorption and Emission of Light in III–V Semiconductors

2020 ◽  
pp. 93-138
Author(s):  
Igor Vurgaftman ◽  
Matthew P. Lumb ◽  
Jerry R. Meyer
Keyword(s):  
Energy Gap ◽  
Stimulated Emission ◽  
Electronic Interactions ◽  
Major Topic ◽  
Semiconductor Crystals ◽  
Zinc Blende ◽  
Light Waves ◽  
Bulk Semiconductors ◽  
Induce Absorption ◽  
Main Ideas

Previous chapters discussed the crystal structure and bandstructure of III–V semiconductors. This chapter shifts to the book’s second major topic: electronic interactions with light. It introduces the main ideas about how light waves propagate in semiconductor crystals and induce absorption, spontaneous emission, and stimulated emission in bulk semiconductors. It also considers the differences between the electronic interactions with light in zinc-blende and wurtzite crystals and what happens as the energy gap of the semiconductor is reduced to zero or when the crystal is two-dimensional.

Alloys and Exotic Materials

2020 ◽  
pp. 197-236
Author(s):  
Vurgaftman Igor
Keyword(s):  
Entire Range ◽  
Energy Gap ◽  
Lattice Structure ◽  
Hexagonal Boron Nitride ◽  
Ternary Alloys ◽  
Optical Parameters ◽  
Dilute Nitrides ◽  
Zinc Blende ◽  
Wurtzite Lattice ◽  
The Common

The chapter describes how the band parameters of ternary and quaternary alloys can be interpolated over the entire range of compositions, and tabulate the non-vanishing bowing parameters for most of the common alloys with both zinc-blende and wurtzite lattice structure. It also describes ordering in some of the ternary alloys, and how ordering affects the energy gap. The band parameters of dilute nitrides, dilute bismides, and hexagonal boron nitride are also examined. Finally, the chapter presents schemes for interpolating the optical parameters of III–V alloys, i.e., the real and imaginary parts of the permittivity or dielectric function.

A formalism for the indirect Auger effect. I

1976 ◽  
Vol 347 (1651) ◽  
pp. 547-564 ◽  
Keyword(s):  
Room Temperature ◽  
Auger Recombination ◽  
Impact Ionization ◽  
Energy Gap ◽  
Electron Collision ◽  
Recombination Coefficient ◽  
Recombination Rates ◽  
Zinc Blende ◽  
Auger Effect ◽  
Ionization Rates

A general formalism has been developed for the calculation of band-band Auger recombination and impact ionization rates in diamond and zinc blende type structures. The energy gap involved in the transition must be of order 1eV or greater, at room temperature, for direct gaps but is arbi­trary for indirect gaps. A recombination coefficient of 28.1 x 10 -32 cm 6 s -1 for GaP (hole-hole-electron collision) has been obtained in reasonable agreement with experiment. The formalism gives better theoretical values for Ge and Si than so far available. This has tended to reduce the recombination rates expected theoretically.

ELECTRONIC, OPTICAL AND MECHANICAL PROPERTIES OF AIIBVI SEMICONDUCTORS

2012 ◽  
Vol 26 (08) ◽  
pp. 1250020 ◽  
Author(s):  
DHEERENDRA SINGH YADAV ◽  
A. S. VERMA
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Energy Gap ◽  
Average Energy ◽  
Compound Semiconductors ◽  
Electronic Polarizability ◽  
Zinc Blende ◽  
Energy Gaps ◽  
Optical And Mechanical Properties ◽  
Good Agreement

The modified dielectric theory of solids is applied to investigate electronic, optical and mechanical properties of A II B VI binary semiconductors ( ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, HgS, HgSe & HgTe ). The values of homopolar gaps (Eh), heteropolar gaps (Ec) and average energy gaps (Eg) were evaluated for these A II B VI groups of binary semiconductors with Zinc-blende (ZB) structure. The derived values of average energy gap (Eg) were found to be in excellent agreement with the values obtained from the Penn model except ZnO . The electronic polarizability was investigated using Chemla's relation and the values were found to be in a very good agreement with the results obtained from the Clausius–Mossotti relation. The crystal ionicity (fi) was evaluated and the obtained values were compared with the values obtained by different researchers. The evaluated values of crystal ionicity were used to calculate the electronic, optical, mechanical properties such as bulk modulus (B in GPa) cohesive energy or total energy (U in Ryd. electron) and microhardness (H in GPa) of these compound semiconductors. A good agreement has been found between calculated and experimental data.

scholarly journals Theoretical Investigation Of Extended Defects In Group-III Nitrides

1997 ◽  
Vol 482 ◽  
Author(s):  
A. F. Wright
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Core Structure ◽  
Band Edge ◽  
Type Material ◽  
Conduction Band Edge ◽  
Extended Defects ◽  
Gap Formation ◽  
Zinc Blende ◽  
Full Core

AbstractWe have investigated two types of extended defects commonly found in AIN, GaN and InN films using density-functional techniques. First, basal-plane stacking faults have been studied for all three compounds. Stacking-fault energies were found to be largest in AIN and smallest in GaN consistent with density-functional results for their wurtzite/zinc-blende energy differences. In addition, the 4H and 6H structures were found to have lower energies than zinc blende for all three compounds. Second, we have investigated the electronic structure and formation energy for an edge dislocation in AIN. The full-core dislocation structure was found to have a filled electronic level approximately 0.55 eV above the valence-band edge and an empty level 1.4 eV below the conduction-band edge. An open-core structure was found to have filled and empty electronic levels closer to the middle of the energy gap. Formation energies for these two geometries suggest that the full-core structure would be expected to form in p-type material whereas both are expected in n-type material.

scholarly journals Electronic interactions of silicon nanocrystals and nanocarbon materials: Hybrid solar cells

2012 ◽  
Vol 84 (12) ◽  
pp. 2629-2639 ◽  
Author(s):  
Vladimir Švrček ◽  
Davide Mariotti
Keyword(s):  
Solar Cells ◽  
Energy Conversion ◽  
Silicon Nanocrystals ◽  
Large Scale ◽  
Energy Gap ◽  
Bulk Heterojunction ◽  
Hybrid Solar Cells ◽  
Exciton Dissociation ◽  
Electronic Interactions ◽  
Nanocarbon Materials

Hybrid inorganic/nanocarbon solar cells represent low-cost solutions for the large-scale manufacturing of energy conversion devices. Here we discuss results that relate to the electronic interactions of nanocarbon materials with freestanding and surfactant-free silicon nanocrystals (Si-ncs) with quantum confinement effects, integrated in bulk-heterojunction solar cells. In particular, we demonstrate the feasibility of bulk-heterojunction photovoltaic solar cells that consist of Si-ncs combined with fullerenes or with semiconducting single-walled carbon nanotubes (SWCNTs). We show that the energy levels between Si-ncs with energy gap exceeding 1.75 eV and fullerenes are adequate for exciton dissociation and carriers (electrons/holes) generation and that hybrid solar cells formed by Si-ncs and semi-conducting SWCNTs favor exciton dissociation only when a distinct chiral index [i.e., (7,5)] is used. While fullerenes show energy conversion capabilities in the visible spectral region (1.7–3.1 eV), the cells containing the SWCNTs, in comparison, have a considerably expanded optical response covering a broad range of the spectrum (0.9–3.1 eV).

Superlattice and Quantum-Well Band Structure

2020 ◽  
pp. 303-342
Author(s):  
Vurgaftman Igor
Keyword(s):  
Band Structure ◽  
Quantum Well ◽  
Quantum Wells ◽  
Quantum Wires ◽  
Energy Gap ◽  
Matrix Elements ◽  
Band Structures ◽  
Zinc Blende

This chapter presents typical band structures for superlattices and quantum wells computed using the methods described in Chapter 9. It identifies important features of the conduction and valence subbands and minibands, their dispersions, optical matrix elements, and characteristic dependences on the materials, thicknesses, and compositions. The changes that occur when the energy gap becomes very small are also discussed. To complete the picture, it considers how the band structure of wurtzite materials differs from their zinc-blende counterparts, as well as the band structure of quantum wires and dots that feature multidimensional confinement.

Transparent conductive nanocomposite layers with polymer matrix and silver nanowires reinforcement

2018 ◽  
Vol 2 (93) ◽  
pp. 59-84 ◽  
Author(s):  
L.A. Dobrzański ◽  
B. Nieradka-Buczek
Keyword(s):  
Electrical Properties ◽  
Polymer Matrix ◽  
Energy Gap ◽  
Light Transmission ◽  
Silver Nanowires ◽  
Matrix Material ◽  
Light Waves ◽  
Composite Layers ◽  
The Matrix ◽  
Materials Used

Purpose: The article deals with one of the completely new groups of composite inorganic nanostructured materials used in the form of surface layers, characterised by unique properties, such as transparency over 84.4% in the field of visible light waves, anti-reflective and electrical properties comparable to semiconductors. Design/methodology/approach: A technology for producing such layers containing not less than 5% of silver nanowires by mixing a colloid containing silver nanowires from fragmented agglomerates by ultrasound homogeniser with the polymer dissolved in chloroform with good bonding to the polymer matrix and of good quality was developed. Findings: It was shown that increasing the content of silver nanowires to 30% in composite layers causes an increase in the refractive coefficient from 1.9 to 2.2 and a decrease in light transmission from 88.1 to 81.9% and a decrease in the value of light reflection from 11.1% up to 6.7%. With an increased content of silver nanowires, these layers show better electrical properties, and the width of the energy gap is reduced from 3.93 eV to 1.60 eV. Composite layers with a mass fraction greater than 5% of silver nanowires show properties analogous to semiconductors despite the metallic nature of their conductivity. Research limitations/implications: The use of silver nanowires as a reinforcement of transparent nanocomposite layers with a poly(methyl methacrylate) PMMA matrix improves selected optical and electrical properties as a result of the uniform distribution of the reinforcing phase in the matrix material. Originality/value: The influence of the content of silver nanowires, layering conditions, applied methods of dispersing silver nanowires in the matrix material on the structure and properties of newly developed nanocomposite layers was determined.

ACTIVATION ENERGIES OF SEMICONDUCTORS WITH THE ZINC BLENDE STRUCTURE

1959 ◽  
Vol 37 (7) ◽  
pp. 1191-1196 ◽  
Author(s):  
W. B. Pearson
Keyword(s):  
Energy Gap ◽  
Activation Energies ◽  
Binding Energies ◽  
Zinc Blende ◽  
Effective Charges ◽  
Zinc Blende Structure ◽  
Systematic Explanation ◽  
Atomic Parameters

Difficulties of determining the binding energies and effective charges on the atoms are the main reason why no systematic explanation of the variation of the size of the energy gap among members of the simplest family of semiconductors—those with the zinc blende structure—has ever been given. It is shown that by the choice of suitable atomic parameters for discussing the activation energies of these compounds these difficulties may be avoided, and the variation of the size of the energy gap between one compound and another can be systematically accounted for. In the treatment which develops no particular distinction need be made between the III–V, II–VI, and I–VII compounds, and it is concluded that the anomalously high or low activation energies, which certain compounds appear to have, are just the result of the relative sizes of the cations and anions in influencing the polarization of the bonds.

scholarly journals Modeling the electronic structure and stability of three aluminum nitride phases

2021 ◽  
Vol 67 (3 May-Jun) ◽  
pp. 343
Author(s):  
J. Ruiz-González ◽  
G. H. Cocoletzi ◽  
L. Morales de la Garza
Keyword(s):  
Aluminum Nitride ◽  
Rock Salt ◽  
Ground State ◽  
Energy Gap ◽  
Ground State Structure ◽  
Cohesion Energy ◽  
Wurtzite Phase ◽  
Zinc Blende ◽  
External Pressures ◽  
Indirect Band Gap

Phase transitions in aluminum nitride (AlN) were investigated by first principles total energy calculations. Three AlN crystal structures were considered: rock salt (NaCl), zinc blende and wurtzite. The cohesion energy was calculated within both GGA and LDA formalisms. According to the cohesion energy results, the ground state corresponds to the hexagonal wurtzite phase, in agreement with experimental evidence. However, the zinc blende and NaCl phases may be formed as metastable structures. To determine the energy gap the modified Becke-Johnson pseudopotential was applied, with results showing good agreement with the experimental data. The ground state structure exhibits direct electronic transitions. However, the zinc blende and NaCl phases show indirect band gap. Provided that external pressures may induce transitions from wurtzite to zinc blende or rock salt, these transitions were also investigated. Estimation of the pressure at the phase transition indicates that small pressures are needed to achieve such transitions.

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