Query: said Ridene

title: Temperature effect on structural, morphological and optical properties of 2D MoS2 layers: An experimental and theoretical study
abstract: In this work, we present experimental and theoretical studies of the effect of temperature on the structural, morphological and optical performance of 2D MoS2 nanosheets. We have used X ray diffraction, Raman, photoluminescence spectroscopies and electron transmission microscopy to study the structural, morphologic and optical properties of MoS2 synthesized by hydrothermal method. The results indicate that, the structuraland optical properties are significantly temperature dependent. The number of MoS2 layers has been estimated from the Raman frequencies of the E12g and A1g vibration modes. For the theoretical study we have used k.p and density matrix to calculate the band structure and optical gain for the 2D MoS2. It is found that the nanosheets exhibit a significant enhancement in the TE polarized optical gain at room temperature. These results show that 2D MoS2 layered is promoters for laser device.

title: Large optical gain from the 2D transition metal dichalcogenides of MoS2/WSe2 quantum wells
abstract: In this work, the optical gain in the new class of 2D materials is calculated for MoS2/WSe2 single quantum well (QW) For this purpose, numerical solution of the k.p equation at (K+ K points of the Brillouin zone is done in order to obtain the energy levels and their corresponding wave functions of electrons and holes in QW. Then, we discussed the band gap dependence on temperature of MoS2 and WSe2 materials. Further, we examined the temperature and the QW width effects on the optical and the maximum of gain. We found that MoS2/WSe2 QW can satisfy the lasing requirements and can give interesting results about the performance of laser emitting devices. The results are compared to the available data reported in the literature.

title: GaSbBi/GaSb quantum well and wire laser diodes
abstract: In this work, we present detailed theoretical studies of the optical gain spectra and the emission wavelength of GaSb1 xBix/GaSb and traditional GaAs1 xBix/GaAs dilute bismide quantum wells and wires (QWs, QWRs) focusing on comparison between their performances. It is found that the optical gain and the emission wavelength of the GaSb based QW and QWRs lasers would be considerably greater than that of the GaAs based QW lasers and QWRs for the same QW QWR width, Bi content and carrier density. The theoretical results were found to be in good agreement with available experimental data, especially for the emission wavelength given by GaSb based QW laser diodes.

title: Mid infrared emission in In x Ga 1 x As/GaAs T shaped quantum wire lasers and its indium composition dependence
abstract: In this work, the emission wavelength has been extended out to 1.3, 1.5, and 2.2 mm for InxGa1 xAs/GaAs T shaped quantum wire (TQWR) using multi band k.p model and variational formalism. We have investigated the impact of the indium composition on the performance of a series of TQWR through a calculation of the optical gain and transition energies. It is found that the optical gain and the emission wavelength are more influenced taking into account the effect of the indium concentration and persisted up at room temperature (RT) The results could open the way to the development of laser communication systems operating at long wavelengths and fabricated from TQWRs structure.

title: Proposal of InP/AlInGaAs single delta quantum well for fiber optic communications
abstract: In this study, InP/AlGaInAs/delta InGaAs single quantum well for fiber optic communications is presented, proposed and compared to the free delta layer even structure. The Al and Ga content and the thickness layers are self consistently optimized using genetic algorithm. It is found that the optimization of structure confirm an improvement in the electron and hole wave function overlap, which leads to a significant enhancement in TE polarized optical gain at room temperature. In addition, the transparency carrier density is significantly reduced by the insertion of delta InGaAs thin layer which can be a necessity for fiber optic communications.

title: Novel T shaped GaSb/InAsN quantum wire for mid infrared laser applications
abstract: In this work, we investigate GaSb InAs 1 x N x T shaped quantum wire active region in mid infrared laser. Multi band k.p model and variational formalism are applied to find the confinement energies, the band structures, and optical gain. We then present a method of numerical calculation that is suited to any T shaped quantum wire. By tuning the quantum wire thickness, the TE and TM polarized optical gain up to 21 x 10 3 cm 1 can be obtained for l 3.11 mm at room temperature (RT) which is very promising to serve as an alternative active region for high efficiency mid infrared laser applications.

title: Self consistent optimization of [111] AlGaInAs/InP MQWs structures lasing at 1.55 mm by a genetic algorithm
abstract: Band structure and optical gain properties of [111] oriented AlGaInAs/AlGaInAs delta InGaAs multi quantum wells, subjected to piezoelectric field, for the near infrared lasers diodes applications was proposed and investigated in this paper. By using genetic algorithm based on optimization technique we demonstrate that the structural parameters can be conveniently optimized to achieve high efficiency laser diode performance at room temperature. In this work, significant optical gain for the wished emission wavelength at 1.55 mm and low threshold injection current are the optimization target. The end result of this optimization is a laser diode based on InP substrate using quaternary compound material of AlGaInAs in both quantum wells and barriers with different composition. It has been shown that the transverse electric polarized optical gain which reaches 3500 cm 1 may be acquired for l 1.55 mm with a threshold carrier density N th 1.310 18 cm 3 which is very promising to serve as an alternative active region for high efficiency near infrared lasers. Finally, from the design presented here, we show that it is possible to apply this technique to a different III V compound semiconductors and wavelength ranging from deep ultra violet to far infrared.

title: High efficiency of AlInGaN/Al(In)GaN delta AlGaN quantum wells for deep ultraviolet emission
abstract: Band structure and optical gain properties of AlInGaN/AlInGaN delta AlGaN quantum wells for deep ultraviolet light emitting and lasers diodes with wavelength l ~229 nm and TE polarized optical gain peak intensity ~1.7 times larger than the conventional AlInN delta GaN was proposed and investigated in this work. The active region is made up of 20 A staggered Al 0.89 In 0.03 Ga 0.08 N/Al 0.8 In 0.01 Ga 0.19 N layers with a 3 A Al 0.46 Ga 0.54 N delta layer. The use of the quaternary AlInGaN well layer permits the independent control of the band gap and the lattice parameter, so that the internal electric field induced by polarizations can be reduced and interband transition energy increases. Therefore, we can predict that the optical performance of the AlInGaN delta AlGaN is more convenient for an emission in the deep ultraviolet than that of the conventional AlInN delta GaN based quantum wells.

title: Effect of hydrostatic pressure on the hole effective mass in a strained InGaAs/GaAs quantum well
abstract: A systematic analysis of the hydrostatic pressure effects on the effective masses of holes in strained single In x Ga 1 x As/GaAs quantum well (Qw) is performed. The strain effect on the shift of the subband energies and the effective masses is also investigated. A 14 band k.p Hamiltonian matrix is used in the calculations and solved by iteration with the Bir Pikus Hamiltonian. Numerical results have been presented over a pressure range from 0 to 16 kbar. Our results show that especially for the calculation of the light hole mass, it is necessary to use the 14 band and not the 8 band k.p model. This is supported by the fact that the 8 band k.p model predicts an increasing mass with pressure which does not reproduce the experimental results. Finally our calculations clearly confirm the available experimental results given in the literature.

title: Hole intersubband transitions in wurtzite and zinc blende strained AlGaN/GaN quantum wells and its interband interaction dependence
abstract: Valence intersubband transitions of the wurtzite (WZ) strained AlGaN/GaN quantum wells are examined theoretically and compared with those of the zinc blende (ZB) ones. In particular, the effect of the interband interaction between conduction (CB) and valence (VB) bands has been taken into account explicitly. We have used the 8 bands k.p model for both WZ and ZB structures to calculate subband energies and wavefunctions of Al0.3Ga0.7N/GaN quantum wells (QWs) The results indicate that, the prominent transitions for both ZB and WZ QWs were found to be essentially related to the heavy and light hole subbands. For the x polarization, we have shown that it is necessary to take into account explicitly the interband interaction between CB and VB. Finally, we can predict that WZ QWs are more convenient than ZB QWs in most applications involving intersubband transitions, especially for the z polarized light.