FAR-INFRARED LASER PHOTOCONDUCTIVITY OF N-GAAS MULTIPLE-QUANTUM WELLSIN A PULSED MAGNETIC-FIELD

Far-infrared laser magnetospectroscopy of a multiple quantum well (MQW ) structure, delta-doped with Si donors in both the wells and the barr iers, has been carried out over the energy range 6-18 meV using a puls ed magnet, the calibration of which is confirmed by cyclotron resonanc e measurements on bulk n-GaAs. Apart from cyclotron resonance, the MQW exhibits a spectral feature at a magnetic field exceeding that of the 1s --> 2p(+) bulk transition at the same laser wavelength. This featu re is attributed to a transition involving electrons in the well which are bound to donor sites in the barriers. (C) 1998 Elsevier Science B .V. All rights reserved.