NEGATIVE VERTICAL PHOTOVOLTAIC RESPONSE OF 2-DIMENSIONAL ELECTRONS INTHE QUANTUM HALL REGIME

The photovoltaic response of a two-dimensional electron system (2DES) is investigated in strong magnetic fields at 4.2 K using a long channe l device with a Schottky gate. When the 2DES is in the quantum Hall (Q H) regime, a large negative photovoltage is observed at the gate. The spectrum of the photovoltage is shifted towards the higher photon ener gy with respect to the cyclotron resonance of the bulk 2DES, suggestin g that the photovoltage is caused by photo-absorption at the edge stat es. The filling factor dependence of the photovoltage spectrum suggest s a nonparabolic edge state dispersion. (C) 1998 Elsevier Science B.V. All rights reserved.