PHOTOGALVANIC EFFECT IN AN ASYMMETRIC SYSTEM OF 3 QUANTUM-WELLS IN A STRONG MAGNETIC-FIELD

The photogalvanic effect (PGE) in an asymmetric undoped system of thre e GaAs/AlGaAs quantum wells illuminated with white light of various in tensities is investigated in magnetic fields up to 75 kOe at temperatu res ranging from 4.2 K up to 300 K. A maximum of the spontaneous photo galvanic current J(PGE) as a function of the magnetic field predicted by A. A. Gorbatsevich et al., JETP Lett. 57, 580 (1993), is observed, Analysis of the experimental data shows that the main initial characte ristic of the PGE is not the spontaneous current but rather the electr omotive force E(PGE) arising in the direction perpendicular to the app lied magnetic field. It is determined that this emf is independent of the intensity of the incident light, increases linearly with the size d of the illuminated region, and decreases slowly with temperature: E( max)(PGE)similar to 0.8 V at 300 K and similar to 0.1 V at 4.2 K for d similar to 3 mm. The curve E(PGE)(H) at room temperature is determine d with allowance for the strong transverse magnetoresistance of the na nostructure. (C) 1996 American Institute of Physics.