Spectroscopic Studies of the Visible and Infrared Luminescence from Er Doped GaN

The visible and infrared luminescence of erbium doped gallium nitride prepared by metal-organic molecular beam epitaxy (MOMBE) and solid-source molecular beam epitaxy (SSMBE) were investigated as a function of excitation wavelength and temperature. Both samples exhibited 1.54 micrometer Er(exp 3+) photoluminescence (PL), but only GaN:Er (SSMBE) showed visible PL lines at 537 and 558 nm. Excitation wavelength dependent PL measurements revealed the existence of multiple Er sites leading to an inhomogeneous line broadening of the Er(exp 3+) intra-4f PL under above-gap pumping. A significant narrowing of the green Er(exp 3+) PL lines was observed when pumping resonantly into an intra-4f transition. This observation suggests that a specific class of Er(exp 3+) ions was selectively excited. A temperature dependent study of the PL intensity ratio and lifetime of the green Er(exp 3+) lines revealed that the two excited states 2H(sub 11/2) and 4S(sub 3/2) are thermally coupled. Considering this thermal coupling and assuming that non-radiative decay is negligibly small at low temperatures, the green luminescence efficiency at room temperature was estimated to be near unity. Published in Materials Science and Engineering, Part B, v81 p116-120, 2001. Prepared in cooperation with University of Florida, Gainesville, FL, and University of Cincinnati, OH. Prepared in collaboration with U.S. Army European Research Office, London, U.K. Sponsored in part by National Aeronautics & Space Administration (NASA) grant NCC-1-251.