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Advances in III-V semiconductor infrared absorbers and detectors
摘要： Advances in bulk III-V semiconductor material such as InGaAsSb and metamorphic InAsSb, as well as in a variety of type-II superlattices such as InGaAs/GaAsSb, InAs/GaSb, and InAs/InAsSb, have provided continuously adjustable cutoff wavelength coverage from the short to the very long wavelength infrared. We perform basic theoretical analysis to provide comparisons of different infrared materials. We also briefly report experimental results on a mid-wavelength InAs/InAsSb type-II superlattice unipolar barrier infrared detector and a focal plane array with significantly higher operating temperature than InSb.
关键词： unipolar barrier,MWIR,infrared detector,e-SWIR,LWIR,antimonide,type-II superlattice,nBn,effective mass
更新于2025-09-23 15:23:52
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Influence of the position dependent effective mass on the nonlinear optical properties in semiparabolic and parabolic quantum well with applied magnetic field
摘要： In the current work, the nonlinear optical properties in GaAs/Ga1?xAlxAs semiparabolic and parabolic quantum well(QW) with constant effective mass(CEM) and position dependent effective mass(PDEM) are estimated for different applied magnetic field. In this regard, we have obtained the analytical expressions of the nonlinear rectification(OR), second harmonic generation(SHG), third harmonic generation(THG), optical absorption coefficients(OACs), and refractive index changes(RICs) by using the compact density matrix formalism. Simultaneously, we obtain the reliable energy eigenvalues and their corresponding eigenfunctions via the finite difference method. According to the obtained results, it is found that: (1)the correct inclusion of PDEM is the cause of a noticeable difference in nonlinear optical properties with respect to the use of CEM. (2)the applied magnetic field bear substantial technological importance in the process of nonlinear optical properties modulation.
关键词： Quantum well,Magnetic field,Position dependent effective mass,Optical properties
更新于2025-09-23 15:23:52
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[IEEE 2018 UKSim-AMSS 20th International Conference on Computer Modelling and Simulation (UKSim) - Cambridge, United Kingdom (2018.3.27-2018.3.29)] 2018 UKSim-AMSS 20th International Conference on Computer Modelling and Simulation (UKSim) - A Multiple Quantum Well Structure Simulator
摘要： A simulator was developed for modeling and designing multiple quantum wells structures such as quantum well infrared photodetectors and quantum cascade laser, based on a single-electron effective mass Schr?dinger equation. It employs box integration finite differences and transfer matrix approaches to find energies of bound and scattering states in the structures. The graphical user interface allows the user to vary easily design parameters including effective mass, layer thickness and number of layers as well as simulation parameters in order to optimize the structure for different device applications and functionality. Three simulation examples were performed on: three coupled quantum wells infrared two-color asymmetric quantum well structure, photodetector structure and on a quantum cascade laser design. The results show an accuracy which is comparable to more complicated simulations.
关键词： Effective mass approximation,TMM,Multiple Quantum Wells Structures,FDM
更新于2025-09-23 15:22:29
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Optical Properties of Energy-Dependent Effective Mass GaAs/GaxIn1?xAs and GaAs/AlxGa1?xAs Quantum Well Systems: A Shooting Method Study
摘要： In this paper, we study the effect of energy-dependent effective mass on optical properties of GaAs/GaxIn1?xAs and GaAs/AlxGa1?xAs quantum well systems through the compact density matrix approach. We solved the resulting non-linear Schro¨dinger equation by a simple shooting method and present the algorithm. We show that the energy-dependent effective mass effect is more important for systems with narrower quantum well systems. By an energy-dependent effective mass assumption, absorption coef?cient peak height increases with increasing the total system length L while in the constant effective mass limit, absorption coef?cient peak heights have not been in?uenced by changing L. In the GaAs/AlxGa1?xAs system, by increasing the number of wells, the linear absorption coef?cient amplitude at ?rst increases and then decreases in the ?xed effective mass approximation and monotonically decreases in the energy-dependent effective mass case. By increasing the number of wells, the linear absorption coef?cient peak position at ?rst shows a blue shift and then shows a redshift. In the GaAs/GaxIn1?xAs system, the situation is more complicated and it is described in more detail in the text. However, GaAs/GaxIn1?xAs quantum well systems have larger values of absorption coef?cient peak heights than GaAs/AlxGa1?xAs ones.
关键词： shooting method,GaAs/GaxIn1?xAs and GaAs/AlxGa1?xAs Quantum wells,refractive index changes,energy-dependent effective mass,absorption coef?cient
更新于2025-09-23 15:21:21
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Hybrid functional calculations of electro-optical properties of novel Ga1a??xInxTe ternary chalcogenides
摘要： Doping GaTe semiconductor with indium can be beneficial in the realization of high-quality radiation detectors. In this study, first-principle calculations based on the density functional theory have been used to investigate the structural and electro-optical properties of Ga1?xInxTe alloys. For the electronic structure calculations, the exchange–correlation functionals are treated with an accurate PBE0 hybrid functional giving improved agreement with experimental band energies. The influence of the In concentration on the energy band gaps is analyzed. Furthermore, the direction for the highest mobility of Ga1?xInxTe is estimated by calculating the effective mass of carriers respecting to the crystallographic directions from calculated electronic band structures. Optical spectra of Ga1?xInxTe are evaluated for all compositions (x = 0, 0.25, 0.5 and 0.75) and for different polarization directions in the range of 0–14 eV. The calculated optical spectra of Ga1–xInxTe are found to have a remarkable redshift as the alloying composition increases. The calculated static dielectric constant for the entire concentration shows that the considered alloys are a high-dielectric constant materials. Our study shows that Ga1?xInxTe alloys exhibit metallic properties in some energy ranges. Our results suggest that the new Ga1?xInxTe alloys are a promising material for radiation detectors, microelectronics and optoelectronic devices.
关键词： First-principles calculations,Band structure,Effective mass,Ga1–xinxte,Dielectric function,PBE0 hybrid functional
更新于2025-09-23 15:21:01
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Investigation of the structural and electronic properties of InP1-xSbx alloy for mid-infrared optoelectronic applications: A TB-mBJ DFT study
摘要： The structural and electronic properties of InP1(cid:1)xSbx supercell structure at different percent of Sb incorporation have been studied under the Density Functional Theory formalism employing WIEN2K package. From the total energy calculations, the supercell lattice structures have been optimized. The structural properties have been calculated from the equation of state which suggests the supercell structures to be signi?cantly stable with a higher degree of compressive ?exibility (speci?cally, at lower percent of Sb incorporation). The contribution of the partial and total DOS (Density of States) of constituent elements to total DOS of the supercell structure has been investigated. The relativistic effects have been assimilated into the band structure calculation, along various high symmetry k directions for each supercell structure. The values obtained for band gap (both, direct and indirect), spin-orbit splitting energy and bowing coef?cient have been observed to vary signi?cantly as a function of Sb mole fraction. Moreover, a relationship has been established between band gap (both, direct and indirect) values and spin-orbit splitting energy with Sb mole fraction. The in?uence of SOC (spin-orbit coupling) effect on the parameters concerning electronic properties has also been analyzed. The effective mass values for conduction and valence sub-bands (heavy hole, light hole and spin orbit split-off hole) near the Brillouin zone has been calculated at different percent of Sb incorporation in InP1(cid:1)xSbx supercell structure. The interpretation of these results obtained suggests InP1(cid:1)xSbx material to be competent for mid-infrared optoelectronic applications.
关键词： III-V semiconductor,Electronic band structure,DOS,DFT calculation,Effective mass calculation,Structural and electronic property
更新于2025-09-23 15:21:01
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Six novel carbon and silicon allotropes with their potential application in photovoltaic field
摘要： By stacking up five novel cagelike structures, three novel three-dimensional (3D) sp3 bonding networks, named hP24, hP30 and hP36, were predicted in this work for the first time. These three newly discovered structures have trigonal unit cell with the space groups of P-3m1, P-3m1 and P3m1, respectively. Using first-principle calculations, the physical properties, including structural, mechanical, electronic and optical properties of C and Si in hP24, hP30 and hP36 phases were systematically studied. All these newly discovered carbon and silicon allotropes were proven to be thermodynamically and mechanically stable. The wide indirect bandgap value in range of 3.89 ~ 4.03 eV suggests that C in hP24, hP30 and hP36 phases have the potential to applied in high frequency and high power electronic devices. The direct bandgap value in range of 0.60 ~ 1.16 eV, the smaller electron and hole effective mass than diamond-Si, and the significantly better photon absorption characteristics than diamond-Si suggest that hP24-Si, hP30-Si and hP36-Si are likely to have better performance in photovoltaic applications than diamond-Si. hP24-Si also have the potential to be applied in infrared detectors.
关键词： carbon and silicon allotropes,effective mass,direct bandgap,photovoltaic applications,stability
更新于2025-09-23 15:19:57
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Impact of dielectric environment on the linear and nonlinear optical properties for CdS/ZnS cylindrical core/shell quantum dots
摘要： By the mean of the effective mass approximation (E.M.A) and compact density matrix method, the energy eigenvalues, linear and nonlinear dielectric function have been theoretically investigated for CdS/ZnS cylindrical core/shell quantum dot embedded in PVA, PMMA and SiO2 matrices. Simulation results showed that the presence of the dielectric mismatch in the QD-matrix system can lead to a significant enhancement of the nonlinear dielectric function. According to our calculations, peaks of the real and imaginary part of the dielectric function can experience a redshift or a blue shift with the appropriate dielectric environment.
关键词： complex dielectric function,Effective mass approximation,cylindrical core/shell quantum dot,density matrix approach
更新于2025-09-23 15:19:57
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Photoelectric process in GaAs quantum dot
摘要： We study the photoelectric process in single electron charged spherical GaAs/Ga1-yAlyAs quantum dot. The effective mass approximation is used with the finite potential at the dot matrix interface including the effect of self-energy. The total cross section of photoelectric process is investigated with the variation of incident photon energy and the molar concentration y of Al in Ga1-yAlyAs matrix material.
关键词： Quantum dot,Effective mass approximation,Finite potential,Photoelectric process
更新于2025-09-23 15:19:57
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Thermopower Modulation Clarification of the Operating Mechanism in Wide Bandgap BaSnO <sub/>3</sub> -SrSnO <sub/>3</sub> Solid-Solution Based Thin Film Transistors
摘要： The transparent oxide semiconductor (TOS) with large bandgap (Eg ≈ 4 eV) based thin-film transistors (TFTs) showing both high carrier mobility and UV–visible transparency has attracted increasing attention as a promising component for next generation optoelectronics. Among TOSs, BaSnO3–SrSnO3 solid-solutions (Eg = 3.5–4.2 eV) are good candidates because the single crystal shows very high mobility. However, the TFT performance has not been optimized due to the lack of fundamental knowledge especially the effective thickness (teff ) and the carrier effective mass (m*). Here, it is demonstrated that the electric field thermopower (S) modulation method addresses this problem by combining with the standard volume carrier concentration (n3D) dependence of S measurements. By comparing the electric field accumulated sheet carrier concentration (n2D) and n3D at same S, it is clarified that the teff (≈n2D/n3D) of the conducting channel becomes thicker with increasing Sr concentration, whereas the m* becomes lighter. The former would be due to the increase of Eg and latter would be due to the enhancement of overlap population of neighboring Sn 5s orbitals. The present analyses technique is useful to experimentally clarify the teff and m*, and essentially important to realize advanced TOS-based TFTs showing both high optical transparency and high mobility.
关键词： electric field thermopower modulation,effective thickness,thin film transistors,BaSnO3–SrSnO3 solid solution,effective mass
更新于2025-09-19 17:15:36