In metalorganic chemical vapor deposition grown GaAs:Er,O samples, at
ambient pressure, only the Er-Ca-20 center is excited by above band ga
p host photoexcitation (host excitation) and shows a sharp infrared lu
minescence spectra due to intra-4f transitions in the Er3+ ion. It is
found, at high pressure, that at least two other Er centers become opt
ically active by host excitation. One of these pressure-induced center
s is assigned to a specific Er center having slightly different atomic
configuration than the Er-Ca-20 center by comparing the pressure-indu
ced photoluminescence (PL) spectra with the site-selective PL spectra.
(C) 1997 American Institute of Physics.