Er-doped GaAs has been grown by migration-enhanced epitaxy. The sample
s were grown at 300, 400, and 500-degrees-C. Secondary ion mass spectr
oscopy measurements showed that the Er concentration in the grown epit
axial layer does not depend on the growth temperature between 300 and
500-degrees-C. All samples showed luminescence due to the Er intra-4f-
shell transition from the I-4(13/2) excited state to the I-4(15/2) gro
und state, but the spectra change drastically when the growth temperat
ure is increased from 300-degrees-C to 400 or 500-degrees-C. The photo
luminescence spectra of the samples grown above 400-degrees-C are simp
ler than that of the sample grown at 300-degrees-C. The spectrum of th
e sample grown at 300-degrees-C became broad after annealing, whereas
the spectra of the samples grown at 400-degrees-C and above showed onl
y changes in the relative intensity of the main luminescence lines. So
me thermally stable Er luminescence centers seem to be preferentially
formed at 400 and 500-degrees-C.