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 epitaxy using two new sources, bis(i-propylcyclopentadienyl)cyclopentadienyl erbium and tris(t-butylcyclopentadienyl) erbium. Controlled Er doping in the range of 10¹⁷-10¹⁸ cm^-3 was achieved using a relatively low source temperature of 90°C. The doping exhibits a second-order dependence on inlet source partial pressure, similar to behavior obtained with cyclopentadienyl Mg dopant sources. Equivalent amounts of oxygen and Er are present in "as-grown" films indicating that the majority of Er dopants probably exist as Er-O complexes in the material. Er³⁺ luminescence at 1.54 μm was measured from the as-grown films, but ion implantation of additional oxygen decreases the emission intensity. Electrical compensation of n-type GaAs layers codoped with Er and Si is directly correlated to the Er concentration. The compensation is proposed to arise from deep centers associated with Er which are responsible for a broad emission band near 0.90 μm present in the photoluminescence spectra of GaAs:Si, Er films.