Nonlinear Charge Spreading Visualized in Voltage-Controlled Lateral Superlattices

Abstract

Voltage-controlled lateral potential superlattices are used to dramatically increase the lifetime of photogenerated carriers in a quantum well. These long lifetimes, together with the ability to deliberately trigger radiative recombination, enable us to directly visualize the spreading character of nonlinear Maxwell relaxation of 2D charges along narrow channels. Our system allows for temporal and spatial resolution of Maxwell kinetics, usually a very fast process and difficult to observe. The observed spreading dynamics of a 2D hole plasma is in perfect agreement with our nonlinear model.

Coulomb effects and carrier diffusion in semiconductor quantum wires

“…6 Photoexcited electron-hole pairs could be created in a well-defined region in the quantum wire. Such a well-defined region could be smaller than the quantum wire length.…”

Manipulating luminescence in semiconductor nanostructures via field‐effect‐tuneable potentials

“…Since the holes are less mobile than the electrons the spreading dynamics observed is that of a two-dimensional hole plasma. Such an experiment made it possible to investigate the Maxwell kinetics in detail with results that are well described by a non-linear model [14].…”

“…Combining spatially and temporally resolved luminescence experiments allows studying the dynamics of the stored carriers, spreading beneath the stripes of the interdigitated gate [14]. As shown in Fig.…”

Dynamics of long-living excitons in tunable potential landscapes

“…They are made out of NiCr (10 nm thickness) and measure a length of 500 µm. The lateral potential modulation is chosen to be sufficiently small to avoid exciton ionisation [11]. Population of the coupled QWs with excitons is performed via subsequent laser illumination for 50 ns, with the time t = 0 ns marking the end of the excitation pulse.…”