Use of quantitative EELS and cathodoluminescence for study of carrier confinement and diffusion in self organized vertical quantum wells

The topic of utilizing coupled map lattice to investigate complex spatiotemporal dynamics has attracted a lot of interest. For exploring the spatiotemporal complexity of a predator-prey system with migration and diffusion, a new three-chain coupled map lattice model is developed in this research. Based on Turing instability analysis, pattern formation conditions for the predator-prey system are derived. Via numerical simulation, rich Turing patterns are found with subtle self-organized structures under diffusion-driven and migration-driven mechanisms. With the variation of migration rates, the predator-prey system exhibits a gradual dynamical transition from diffusion-driven patterns to migration-driven patterns. Moreover, new results, the self-organization of non-Turing patterns, are also revealed. We find that even in the cases where the nonspatial predator-prey system reaches collapse, the migration can still drive pattern self-organization. These non-Turing patterns suggest many new possible ways for the coexistence of predator and prey in space, under the effects of migration and diffusion.

Download Full-text

Carrier confinement in GaInN/AlGaN/GaN quantum wells with asymmetric barriers: direction of the piezoelectric field

Materials Science and Engineering B ◽

10.1016/s0921-5107(98)00361-4 ◽

1999 ◽

Vol 59 (1-3) ◽

pp. 315-318 ◽

Cited By ~ 10

Author(s):

Jin Seo Im ◽

H Kollmer ◽

J Off ◽

F Scholz ◽

A Hangleiter

Keyword(s):

Quantum Wells ◽

Carrier Confinement ◽

Piezoelectric Field ◽

Asymmetric Barriers

Download Full-text

Thermodynamics and Diffusion of Free Trions in Mixed Type GaAs/AlAs Quantum Wells

MRS Proceedings ◽

10.1557/proc-417-309 ◽

1995 ◽

Vol 417 ◽

Author(s):

H. W. Yoon ◽

Arza Ron ◽

M. D. Sturge ◽

L. N. Pfeiffer

Keyword(s):

Quantum Wells ◽

Mixed Type ◽

Radiative Decay ◽

Bath Temperature ◽

Simultaneous Presence ◽

Spatially Resolved ◽

Decay Times ◽

Free Particles ◽

20 Nm ◽

And Diffusion

AbstractAn emission line which depends on the simultaneous presence of excitons and < 2×1010 cm−2 free photoexcited electrons in a 20 nm quantum well is shown to be due to the recombination of free negatively charged excitons ( “trions”). The binding energy is 1.3 meV and the lifetime is 1/4 that of the exciton. The increase in the radiative decay times of excitons and trions with increasing bath temperature is consistent with that of free particles. More directly, from time- and spatially-resolved measurements, we find that trions are localized at 5 K, and with increasing bath temperature both excitons and trions become mobile. The diffusivity of trions and excitons increases linearly with bath temperature, and at 10 K, the trion diffusivity is found to be factor of two lower than the exciton diffusivity. Our results are the first direct experimental evidence for free trions in GaAs quantum wells.

Download Full-text