OPTICAL NMR FROM SINGLE GAAS/ALGAAS QUANTUM WELLS

摘要

In this work, results of detailed optical nuclear magnetic resonance (ONMR) studies of a series of five single GaAs/AlGaAs quantum wells centre-doped with beryllium are presented. Signals from As-75, Ga-69 and Ga-71 nuclei were clearly observed from single quantum wells with widths ranging from 42 to 143 Angstrom. The Al-27 resonance from the AlGaAs barrier layers was not observed, confirming that the ONMR signal originated within the individual quantum wells. De-polarization of excitonic 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 orders of magnitude. Through studies of effects of optical power, RF power and external magnetic field on the ONMR signal, this work establishes and extends the range of experimental conditions suitable for ONMR in GaAs-based structures. [References: 12]