ACTA

Stochastic Carrier Dynamics in Semiconductor Superlattices

T.M. Fromhold^a, S. Bujkiewicz^a, A. Patanè^a, S.P. Stapleton^a, D. Sherwood^a, D. Fowler^a, J. Cooper^a, L. Eaves^a, A.E. Belyaev^a, A.A. Krokhin^a,b,c, A. Neumann^a, P.B. Wilkinson^a, N.S. Sankeshwar^a, M. Henini^a and F.W. Sheard^a
^aSchool of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK,
^bInstituto de Fisica, Universidad Autonoma de Puebla, Puebla 72570, Mexico,
^cCenter for Nonlinear Science, University of North Texas, P.O. Box 5368, Denton, Texas 762203, USA

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Received: 19 05 2005;

We explore a new regime of hot carrier dynamics, in which electrons in a superlattice miniband exhibit a unique type of stochastic motion when a magnetic field is tilted at an angleθ to the superlattice axis. Remarkably, the dynamics of a miniband electron in a tilted magnetic field reduce to a one-dimensional simple harmonic oscillator, of angular frequencyω_C cosθ, whereω_C is the cyclotron frequency, driven by a time-dependent plane wave whose angular frequency equals the Bloch frequencyω_B. At bias voltages for whichω_B=nω_C cosθ, where n is an integer, the electron orbits change from localised Bloch-like trajectories to unbounded stochastic orbits, which diffuse rapidly through intricate web patterns in phase space. To quantify how these webs affect electron transport, we make drift-diffusion calculations of the current-voltage curves including the effects of space-charge build up. When the magnetic field is tilted, our simulations reveal a large resonant peak, which originates from stochastic delocalisation of the electron orbits. We show that the corresponding quantised eigenstates change discontinuously from a highly localised character when the system is off resonance to a fully delocalised form when the resonance condition is satisfied.

DOI: 10.12693/APhysPolA.109.43
PACS numbers:73.20.At, 73.21.Cd