INTERNAL TRANSITIONS OF EXCITONS AND HOLE CYCLOTRON-RESONANCE IN UNDOPED GAAS ALGAAS QUANTUM-WELLS BY OPTICALLY DETECTED RESONANCE SPECTROSCOPY/

Optically detected resonance (ODR) spectroscopy has been used to study electron and hole cyclotron resonance (CR) and various internal excit onic transitions in one sample in magnetic fields up to 15 T. The cons equences of the cylindrical symmetry of the Hamiltonian for this syste m are observed directly. The energy difference between electron and ho le CR equals the energy difference between any pair of Is -->np(+/-) i nternal excitonic transitions (IET). The two principal hole CR transit ions were identified from comparison with theoretical calculations. In addition to the nearly degenerate Is --> 2p(+) IET(s), two 1s --> 2p( -) IETs resulting from the two distinct heavy-hole magnetoexcitons wer e observed. The capability of observing electron and hole CR as well a s several IETs in a single sample is unique to the ODR technique and d emonstrates its potential for elucidating the electronic states of sem iconductor nanostructures. (C) 1998 Elsevier Science B.V. All rights r eserved.