Multiple Quantum Well AlGaAs Nanowires

This letter reports on the growth, structure and luminescent properties of individual multiple quantum well (MQW) AlGaAs nanowires (NWs). The composition modulations (MQWs) are obtained by alternating the elemental flux of Al and Ga during the molecular beam epitaxy growth of the AlGaAs wire on GaAs (111)B substrates. Transmission electron microscopy and energy dispersive X-ray spectroscopy performed on individual NWs are consistent with a configuration composed of conical segments stacked along the NW axis. Micro-photoluminescence measurements and confocal microscopy showed enhanced light emission from the MQW NWs as compared to non-segmented NWs due to carrier confinement and sidewall passivation

Resonant Fibonacci Quantum Well Structures

We propose a resonant one-dimensional quasicrystal, namely, a multiple quantum well (MQW) structure satisfying the Fibonacci-chain rule with the golden ratio between the long and short inter-well distances. The resonant Bragg condition is generalized from the periodic to Fibonacci MQWs. A dispersion equation for exciton-polaritons is derived in the two-wave approximation, the effective allowed and forbidden bands are found. The reflection spectra from the proposed structures are calculated as a function of the well number and detuning from the Bragg condition.Comment: 5 pages, 3 figures, submitted to Phys. Rev.

Modeling Si/SiGe/Si Quantum Well Solar Cell Using Different Well Width and Mole Fraction

Quantum Well Solar Cell ( QWSC) was proposed as a means to achieve higher efficiencies compare with conventional monolithic solar cell structures. Quantum well formed by adding lower band gap material within intrinsic region of p-i-n solar cell with less than 100 A thicknesses. In this research, five structure of QWSC device were designed with different quantum well thickness. Each structure using different SiGe mole fraction in order to achieve the influence of mole fraction variation to quantum efficiency (QE). Parameters of SiGe in simulations were obtained from various references to use with PC1D and Simwin Software. From simulation result, quantum efficiency will increase from mole fraction 0.2 (84.5135 %) until reaching maximum efficiency at mole fraction 0.75 (91.5703 %). Quantum efficiency begin to decrease at mole fraction higher than 0.75. At mole fraction 0.85 quantum efficiency equal to 90.4830 % and at mole fraction 0.95 quantum efficiency sharply become 71.6327 %.Index Terms— Solar cell, quantum well solar cell, SiGe

Quantum well lasers -- Gain, spectra, dynamics

We discuss a number of theoretical and experimental issues in quantum well lasers with emphasis on the basic behavior of the gain, the field spectrum, and the modulation dynamics. It is revealed that the use of quantum well structures results in improvement of these properties and brings several new concepts to optical semiconductor devices

Physical model of quantum-well infrared photodetectors

A fully quantum mechanical model for electron transport in quantum well infrared photodetectors is presented, based on a self-consistent solution of the coupled rate equations. The important macroscopic parameters like current density, responsivity and capture probability can be estimated directly from this first principles calculation. The applicability of the model was tested by comparison with experimental measurements from a GaAs/AlGaAs device, and good agreement was found. The model is general and can be applied to any other material system or QWIP design