Suppression of electron-hole-pair recombination in edge states in quantum Hall regimes

Far-infrared (FIR) photoconductivity induced by cyclotron resonance in edge slates of quantum Hall devices are studied by carrying out time-resolved m easurements. It is found that the recombination of electron-hole pairs exci ted via cyclotron resonance in edge states is significantly suppressed, yie lding a surprisingly long recombination lifetime ( similar to 10 ms). This is in marked contrast to much shorter recombination lifetimes ( similar to 1 ms) in bulk states. The experimental results lead us to suggest that the edge-state FIR photoconductivity is induced by an effect of electric polari zation. This implies also that edge states can be a promising candidate for application as a FIR detector. (C) 2001 Elsevier Science B.V. All rights r eserved.