EXCITED-STATES OF HYDROGENIC IMPURITIES IN QUANTUM-WELLS IN MAGNETIC-FIELDS

Quasi-two-dimensional hydrogenic impurity levels in quantum wells unde r the influence of magnetic fields are investigated. Experimentally, 1 s --> np (n = 2, 3, 4) transition energies in quantum wells of various widths are measured by the photoconductivity technique for magnetic f ields up to 9 T Theoretically, these energies are calculated by a new variational method that is valid for the whole range of magnetic field strengths, from the zero-field limit to the high-held limit. Good agr eement is achieved for every transition for well widths up to similar to 300 Angstrom, for which the confinement effect is appreciable. Cons istent discrepancies found for 450 Angstrom are expected to be account ed for by including subband mixing because of the wide width and small subband separation. Our study demonstrates that the simple variationa l method can produce good results for highly excited levels in magneti c fields provided that the confinement due to the quantum well is suff iciently strong.