Dislocation-related photoluminescence at 0.806 and 0.873 eV is observed in erbium-doped silicon epi layers grown by liquid-phase epitaxy on (100) Si wafers. These signals are detected at T = 2 K only on epi layers deposited on Czochralski grown silicon substrates. No luminescence is observed when float zone-grown substrates are used. The peak intensity shows temperature quenching, but the signal remains detectable up to 195 K. The luminescence apparently is due to dislocations in silicon in the simultaneous presence of high oxygen concentration and erbium impurities. A comparison with the typical infrared emission from erbium-implanted silicon samples is presented.