GROWTH-STUDIES OF ERBIUM-DOPED GAAS DEPOSITED BY METALORGANIC VAPOR-PHASE EPITAXY USING NOVEL CYCLOPENTADIENYL-BASED ERBIUM SOURCES

Erbium-doped GaAs layers were grown by metalorganic vapor phase epitax y using two new sources, bis(i-propylcyclopentadienyl)cyclopentadienyl erbium and tris(t-butylcyclopentadienyl) erbium. Controlled Er doping in the range of 10(17)-10(18) cm-3 was achieved using a relatively lo w source temperature of 90-degrees-C. The doping exhibits a second-ord er dependence on inlet source partial pressure, similar to behavior ob tained with cyclopentadienyl Mg dopant sources. Equivalent amounts of oxygen and Er are present in ''as-grown'' films indicating that the ma jority of Er dopants probably exist as Er-O complexes in the material. Er3+ luminescence at 1.54 mum was measured from the as-grown films, b ut ion implantation of additional oxygen decreases the emission intens ity. Electrical compensation of n-type GaAs layers codoped with Er and Si is directly correlated to the Er concentration. The compensation i s proposed to arise from deep centers associated with Er which are res ponsible for a broad emission band near 0.90 mum present in the photol uminescence spectra of GaAs:Si, Er films.