A comparison of optical properties of disc-like and spherical quantum dots

2018 ◽  
Vol 27 (03) ◽  
pp. 1850034
Author(s):  
Vildan Üstoğlu Ünal ◽  
Erem Birşey ◽  
Ertan Akşahin
Keyword(s):  
Quantum Dots ◽  
Refractive Index ◽  
Optical Properties ◽  
Optical Absorption ◽  
Electric Field ◽  
Electronic Structures ◽  
Electric Field Effect ◽  
Total Change ◽  
Absorption Increase ◽  
Mass Approximation

The optical properties of quantum dots (QDs) are of interest to many researchers. In this study, the optical coeefficients analyzed include the optical absorption, the refractive index; both the linear and nonlinear cases together with the electric field effect. The electronic structures of the disc-like and spherical QDs are calculated by using the effective-mass approximation. The results show that the total change in the refractive index and the optical absorption increase with increasing QD size, the peaks are shifted with the changing QD size. The nonlinear optical properties increase with the external electric field and the optical intensity. Comparison of QD types shows that the peaks are red-shifted for the disc-like QD and lower than those in the spherical QD case.

Electronic structures and optical properties of arsenene and antimonene under strain and an electric field

2018 ◽  
Vol 6 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Huabing Shu ◽  
Yunhai Li ◽  
Xianghong Niu ◽  
JiYuan Guo
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Electric Field ◽  
Absorption Spectra ◽  
Electronic Structures ◽  
Optical Absorption Spectra

The optical absorption spectra of hexagonal arsenene (β-As) and antimonene (β-Sb).

Linear and nonlinear optical absorption coefficients and refractive index changes in Morse quantum wells under electric field

2016 ◽  
Vol 30 (30) ◽  
pp. 1650209 ◽  
Author(s):  
S. Sakiroglu
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Optical Absorption ◽  
Electric Field ◽  
Quantum Wells ◽  
Nonlinear Optical ◽  
Absorption Coefficients ◽  
Nonlinear Optical Absorption ◽  
Index Changes ◽  
Linear And Nonlinear

In this paper, we investigate theoretically the effects of electric field on the linear and nonlinear optical properties of Morse quantum wells considering a two-level system. The effective mass approximation and the envelope function approach are used to calculate the energy levels and wave functions. The analytical expressions of the optical properties are obtained by using the compact density-matrix approach. The linear and third-order nonlinear optical absorption coefficients and the refractive index changes are investigated as a function of the incident photon energy for several configurations of the structural parameter and the applied electric field. Numerical results, presented for a typical GaAs/AlGaAs quantum well, reveal that the electric field has a significant effect on the optical characteristics of these structures and intersubband transitions can be modified by tuning the structural range parameter of the potential.

scholarly journals Comparative Study on Electronic Structure and Optical Properties of α-Fe2O3, Ag/α-Fe2O3 and S/α-Fe2O3

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 424
Author(s):  
Cuihua Zhao ◽  
Baishi Li ◽  
Xi Zhou ◽  
Jianhua Chen ◽  
Hongqun Tang
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Electronic Structures ◽  
Density Functional ◽  
Peak Strength ◽  
Visible Range ◽  
High Symmetry ◽  
Functional Theory ◽  
Optical Absorption Peak ◽  
Calculation Results

The electronic structures and optical properties of pure, Ag-doped and S-doped α-Fe2O3 were studied using density functional theory (DFT). The calculation results show that the structure of α-Fe2O3 crystal changes after Ag and S doping, which leads to the different points of the high symmetry of Ag-doped and S-doped α-Fe2O3 with that of pure α-Fe2O3 in the energy band, as well as different Brillouin paths. In addition, the band gap of α-Fe2O3 becomes smaller after Ag and S doping, and the optical absorption peak shifts slightly toward the short wavelength, with the increased peak strength of S/α-Fe2O3 and the decreased peak strength of Ag/α-Fe2O3. However, the optical absorption in the visible range is enhanced after Ag and S doping compared with that of pure α-Fe2O3 when the wavelength is greater than 380 nm, and the optical absorption of S-doped α-Fe2O3 is stronger than that of Ag-doped α-Fe2O3.

LINEAR AND NONLINEAR INTERSUBBAND OPTICAL ABSORPTION OF FINITE AND INFINITE SEMI-PARABOLIC QUANTUM WELLS

2011 ◽  
Vol 25 (07) ◽  
pp. 497-507 ◽  
Author(s):  
M. J. KARIMI ◽  
A. KESHAVARZ ◽  
A. POOSTFORUSH
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Optical Absorption ◽  
Quantum Well ◽  
Quantum Wells ◽  
Resonant Peak ◽  
Energy Eigenvalues ◽  
Finite Case ◽  
Infinite Case ◽  
Index Changes

In this work, the optical absorption coefficients and the refractive index changes for the infinite and finite semi-parabolic quantum well are calculated. Numerical calculations are performed for typical GaAs / Al x Ga 1-x As semi-parabolic quantum well. The energy eigenvalues and eigenfunctions of these systems are calculated numerically. Optical properties are obtained using the compact density matrix approach. Results show that the energy eigenvalues and the matrix elements of the infinite and finite cases are different. The calculations reveal that the resonant peaks of the optical properties of the finite case occur at lower values of the incident photon energy with respect to the infinite case. Results indicate that the maximum value of the refractive index changes for the finite case are greater than that of the infinite case. Our calculations also show that in contrast to the infinite case, the resonant peak value of the total absorption coefficient in the case of the finite well is a non-monotonic function of the semi-parabolic confinement frequency.

Tunable electronic properties of GaS-SnS2 heterostructure by strain and electric field

2021 ◽  
Author(s):  
Dahua Ren ◽  
Qiang Li ◽  
Kai Qian ◽  
Xingyi Tan
Keyword(s):  
Optical Properties ◽  
Electric Field ◽  
Visible Light ◽  
Electronic Properties ◽  
Electronic Structures ◽  
Density Functional ◽  
Band Alignment ◽  
Promising Candidate ◽  
Functional Theory ◽  
External Strain

Abstract Vertically stacked heterostructures have received extensive attention because of their tunable electronic structures and outstanding optical properties. In this work, we have studied the structural, electronic and optical properties of vertically stacked GaS-SnS2 heterostructure under the frame of density functional theory. We find that the stacked GaS-SnS2 heterostructure is a semiconductor with suitable indirect band gaps of 1.82 eV, exhibiting a type-II band alignment for easily separating the photo-generated carriers. The electronic properties of GaS-SnS2 heterostructure can be effectively tuned by external strain and electric field. The optical absorption of GaS-SnS2 heterostructure is more enhanced by comparison with the GaS monolayer and SnS2 monolayer in the visible light. Our results suggest that GaS-SnS2 heterostructure is a promising candidate for the photocatalyst and photoelectronic devices in visible light.

Oxygen migration and optical properties of coronene oxides and their persulfurated derivatives: insight into the electric field effect and the oxygen-site dependence

2020 ◽  
Vol 22 (35) ◽  
pp. 20078-20086
Author(s):  
Qing Zhang ◽  
Yuanyuan Li ◽  
Zexing Cao
Keyword(s):  
Optical Properties ◽  
Electric Field ◽  
External Electric Field ◽  
Field Effect ◽  
Electric Field Effect ◽  
Oxygen Migration ◽  
Site Dependence ◽  
Oxygen Site ◽  
Insight Into

Oxygen migration on the surface of coronene (C24) epoxides and their persulfurated derivatives (PSCs) can be easily tuned by an external electric field and their low-lying states show a remarkable oxygen-site dependence.

Optical Properties and Electronic Structures of Sexithiophene

2010 ◽  
Vol 428-429 ◽  
pp. 475-478 ◽  
Author(s):  
Bao Gai Zhai ◽  
Yuan Ming Huang
Keyword(s):  
Optical Properties ◽  
Optical Absorption ◽  
Ultraviolet Light ◽  
Organic Semiconductor ◽  
Electronic Structures ◽  
Light Emission ◽  
Visible Spectroscopy ◽  
Time Resolved ◽  
Pump And Probe ◽  
Green Photoluminescence

The optical properties and electronic structures of an organic semiconductor sexithiophene have been investigated with ultraviolet-visible spectroscopy, cw photospectroscopy and time-resolved photospectroscopy, respectively. Sexithiophene in dilute tetrahydrofuran solutions can absorb photons at 400 nm while it can give off strong green photoluminescence at 550 nm under the excitation of 325 nm ultraviolet light. With the assistance of calculated electronic structures and pump-and-probe characterization, our results indicate that both the optical absorption and the light emission of the sexithiophene are controlled by the p-conjugation of the oligothiophene.

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