The photoluminescence produced by four MOCVD grown epitaxial thin film samples was studied to give insight into sample quality. The four samples under this study were GaAs on a GaAs substrate, Al_.25Ga_.75As on a GaAs substrate, Al_.30Ga_.7OAs on a GaAs substrate, and GaSb on a GaSb substrate. Excitation was achieved through the use of the 514.0 nm line of an argon ion laser, and sample cooling was attained by use of a cryostat cooler using helium gas to attain a low temperature limit of 10°K. The GaAs and Al_.30Ga_.7OAs samples exhibited typical spectra for MOCVD grown samples produced by other sources in the widths of the resulting BE peaks and in the characterisitics, of their acceptor-induced transitions. The narrow, prominent BE peaks of the Al_.25Ga_.75As and GaSb samples had shown them to be of exceptional quality.