Local structure and bonding of Er in GaN: A contrast with Er in Si

X-ray absorption measurements from relatively high concentrations of Er (> 0.1 at. %) doped in GaN films show that Er occupies the Ga site with an unp recedentedly short Er-N bond length. Electroluminescence intensities from t hese GaN:Er films correlate with the concentration of Er atoms that replace Ga, not with the abundantly present O impurities in the host. Simple chemi cal concepts are used to explain each of these results and their striking d ifference from those obtained for Er-doped Si. (C) 2000 American Institute of Physics. [S0003-6951(00)03320-9].