Er luminescence centers in GaAs grown by migration-enhanced epitaxy

Abstract

Er-doped GaAs has been grown by migration-enhanced epitaxy. The samples were grown at 300, 400, and 500 °C. Secondary ion mass spectroscopy measurements showed that the Er concentration in the grown epitaxial layer does not depend on the growth temperature between 300 and 500 °C. All samples showed luminescence due to the Er intra-4f-shell transition from the 4I13/2 excited state to the 4I15/2 ground state, but the spectra change drastically when the growth temperature is increased from 300 °C to 400 or 500 °C. The photoluminescence spectra of the samples grown above 400 °C are simpler than that of the sample grown at 300 °C. The spectrum of the sample grown at 300 °C became broad after annealing, whereas the spectra of the samples grown at 400 °C and above showed only changes in the relative intensity of the main luminescence lines. Some thermally stable Er luminescence centers seem to be preferentially formed at 400 and 500 °C.