OPTICAL NMR FROM SINGLE GAAS ALGAAS QUANTUM-WELLS/

In this work, results of detailed optical nuclear magnetic resonance ( ONMR) studies of a series of five single GaAs/AlGaAs quantum wells cen tre-doped with beryllium are presented. Signals from As-75, Ga-69 and Ga-71 nuclei were clearly observed from single quantum wells with widt hs ranging from 42 to 143 Angstrom. The Al-27 resonance from the AlGaA s barrier layers was not observed, confirming that the ONMR signal ori ginated within the individual quantum wells. De-polarization of excito nic luminescence from a 60 Angstrom wide quantum well of up to 70% was observed under conditions of adiabatic fast passage through the As-75 resonance. The signal originated from approximately 10-11 nuclei and represents an increase in sensitivity over conventional NMR of 5-6 ord ers of magnitude. Through studies of effects of optical power, RF powe r and external magnetic field on the ONMR signal, this work establishe s and extends the range of experimental conditions suitable for ONMR i n GaAs-based structures.