Low-temperature illumination and annealing of ultra-high quality quantum   wells
  The effects of low temperature illumination and annealing on fractional quantum Hall (FQH) characteristics of a GaAs/AlGaAs quantum well are investigated. Illumination alone, below 1 K, decreases the density of the 2DEG electrons by more than an order of magnitude and resets the sample to a repeatable initial state. Subsequent thermal annealing at a few Kelvin restores the original density and dramatically improves FQH characteristics. A reliable illumination and annealing recipe is developed that yields an energy gap of 600 mK for the 5/2 state. 
Mohammad Samani, Alexander V. Rossokhaty, Ebrahim Sajadi, Silvia   L\"uscher, Joshua A. Folk, John D. Watson, Geoffrey C. Ga...
cond-mat.mes-hall