Quantum well

About: Quantum well is a research topic. Over the lifetime, 44627 publications have been published within this topic receiving 674023 citations. The topic is also known as: QW & quantum potential well.

Effect of phonon bottleneck on quantum-dot laser performance

Abstract: The effect of phonon bottleneck on quantum-dot laser performance is examined by solving the carrier-photon rate equations including the carrier relaxation process into the quantum-dot ground state. We show that the retarded carrier relaxation due to phonon bottleneck degrades the threshold current and the external quantum efficiency. We also show that quantum-dot lasers are quite sensitive to the crystal quality outside as well as inside quantum dots. Our results clarified that the relaxation lifetime should be less than about 10 ps to fully utilize the laser potential originating from the quantum-dot discrete energy states.

Electronic states in gallium arsenide quantum wells probed by optically pumped NMR.

Abstract: An optical pumping technique was used to enhance and localize nuclear magnetic resonance (NMR) signals from an n-doped GaAs/Al0.1Ga0.9As multiple quantum well structure, permitting direct radio-frequency measurements of gallium-71 NMR spectra and nuclear spin-lattice relaxation rates (1/T1) as functions of temperature (1.6 K < T < 4.2 K) and the Landau level filling factor (0.66 < v < 1.76). The measurements reveal effects of electron-electron interactions on the energy levels and spin states of the two-dimensional electron system confined in the GaAs wells. Minima in 1/T1 at v approximately 1 and v approximately 2/3 indicate energy gaps for electronic excitations in both integer and fractional quantum Hall states. Rapid, temperature-independent relaxation at intermediate v values indicates a manifold of low-lying electronic states with mixed spin polarizations.

Intersubband optical absorption in a quantum well with an applied electric field.

Abstract: We present new results for the electric field dependence of the intersubband optical absorption within the conduction band of a quantum well. We show that for increasing electric field the absorption peak corresponding to the transition of states 1\ensuremath{\rightarrow}2 is shifted higher in energy and the peak amplitude is increased. These features are different from those of the exciton absorption. It is also found that the transition 1\ensuremath{\rightarrow}3, forbidden when F=0, is possible when F is nonzero.

Semiconductor laser element

Abstract: PURPOSE:To improve the high output and low noise characteristic by constructing an active layer of a single quantum well layer and superlattice multiple quantum well layers provided on the upper and lower surfaces thereof and forming a ridged waveguide structure for obtaining a self-oscillating laser element. CONSTITUTION:An active layer is constructed of a single quantum well layer 5 and superlattice multiple quantum well layers 4, 6 provided on the upper and lower surfaces thereof, and composition, film thickness, and impurity concentration of respective layers 4, 5, 6 are caused by have predetermined values. A light waveguide layer, on the opposite side of a semiconductor substrate with respect to the active layer, has a mesa-stripe-like ridged part extending in the resonator length direction, and light absorption and current constriction parts are formed on the light waveguide layer with the ridge part at the both ends of the ridged part, and self-oscillation is effected. Therefore, the laser light distribution is controlled and the light absorption layer is provided at a predetermined position relative to the active layer, so that the effective refraction index difference in the lateral direction of the active layer can be caused to have a desired value. Thus, a high output characteristic required by a writing and erasing light source for an optical disk, and a low noise characteristic required by a reading light source can be obtained.