Spontaneous interlayer exciton coherence in quantum Hall bilayers at v=1 and v=2: a tutorial
Solid State Communications Elsevier 134:1-2 (2005) 81-88
Dynamics of the in-plane charge separation front in a two-dimensional electron-hole gas
Physical Review B - Condensed Matter and Materials Physics 71:4 (2005)
Abstract:
We show both experimentally and theoretically that the recently observed optically induced in-plane charge separation in quantum well (QW) structures and the exciton ring emission pattern at this charge separation boundary have an extremely long lifetime. The oppositely charged carriers remain separated and provide a reservoir of excitons at their boundary with a persistent emission which lasts hundreds of microseconds (orders of magnitude longer than their recombination time) after the external excitation is removed. This long lifetime is due to an interplay between the slow in-plane carrier diffusion and slow carrier tunneling perpendicular to the QW plane. ©2005 The American Physical Society.Interlayer correlations versus intralayer correlations in a Quantum Hall bilayer at total filling one
Journal De Physique. IV : JP 131 (2005) 283-284
Abstract:
In Quantum Hall bilayers, at total filling factor one, a transition from a compressible phase with weak interlayer correlations to an incompressible phase with strong interlayer correlations is observed as the distance between the two layers is reduced. The transition between these two regimes can be understood using a trial wavefunction approach based on the composite particle picture. © EDP Sciences.Quantum and transport lifetimes in a tunable low-density AlGaN/GaN two-dimensional electron gas
Applied Physics Letters 85:22 (2004) 5278-5280
Abstract:
We experimentally determine the density dependence of the transport lifetime (τ t) obtained from low-field Hall measurements and the quantum lifetime (τ q) derived from analysis of the amplitude of Shubnikov-de Haas oscillations in a tunable high mobility two-dimensional electron gas (2DEG) in a Al 0.06Ga 0.94N/GaN heterostructure. Using an insulated gate structure, we are able to tune the 2DEG density from 2 × 10 11 to 2 × 10 12 cm -2, and thus, monitor the evolution of the scattering times in a single sample at T=0.3 K in a previously unexplored density regime. The transport lifetime τ t is a strong function of electron density, increasing from ∼2.7 ps at n e=2 × 10 11 cm -2 to ∼11 ps at n e= 1.75 × 10 12cm -2. Conversely, we find that the quantum scattering time τ q is relatively insensitive to changes in electron density over this range. The data suggest that dislocation scattering accounts for the density dependence of τ q as well as τ t in our low-density sample. © 2004 American Institute of Physics.Moving beyond a simple model of luminescence rings in quantum well structures
Journal of Physics Condensed Matter 16:35 (2004)