A zeeman study of the 1.54 micrometer transition in molecular beam epitaxial GaAs-Er.

Er-doped GaAs grown under special molecular beam epitaxy conditions emits strong luminescence at 1.54 mym. The dominant transition of the spectrum was found to be extremely sharp (0.04 cm E-1) at 4.2 K. Zeeman measurements on this specific transition give complicated angular dependence patterns. Analysis of our data reveals monoclinic I symmetry (close to rhombic I) for the crystal field, with unexpectedly low g-factors (g(1y) = 2.0; g(2y) = 1.5) for the upper and the lower Kramers doublet states, all others being equal to zero, and the angle Theta being (001) and z equal to 7 degrees. Preliminary crystal-field calculations and possible microscopic models are discussed. (IAF)