Luminescence measurements were performed on high purity epitaxial n-GaAs ( 1 × 10 14 cm 3 < n < 3 × 10 15 cm 3 ) for various excitation intensities I 0 in the range 8 mW cm 2 < I 0 < 4 W cm 2 . The luminescence line corresponding to the radiative decay of the shallow donor bound exciton, (D 0, X), broadens with increasing I 0 and appears as a doublet for I 0 ≳ 1 W cm 2 , while the two-electron replica of the (D 0, X) remains a single narrow line. The doublet structure of the (D 0, X) at elevated excitation levels is due to missing luminescence intensity in the center of the line as a consequence of low (D 0, X) concentration in a layer extending 1–2 μm from the sample surface into the bulk. The low concentration of (D 0, X) is attributed to capture of (D 0, X) quanta into surface states, extending to lower energies from the Fermi level fixed by the shallow donors. Comparison of the present results with luminescence spectra obtained by various authors reveals, that unexplained spectral features in the (D 0, X) region of n-GaAs reported in the literature are a consequence of high excitation intensity and correspond to the effect reported here. In partly compensated p-GaAs with donor concentrations as given above, the (D 0, X) did not transform into a doublet structure even at W cm 2 excitation intensity.