Treatment of anhydrous rare earth chlorides with three equivalents of lithium 1,3-di-tertbutylacetamidinate (prepared in situ from the di-tert-butylcarbodiimide and methyllithium) in tetrahydrofuran at ambient temperature afforded Ln( t BuNC(CH 3 )N t Bu) 3 (Ln = Y, La, Ce, Nd, Eu, Er, Lu) in 57-72% isolated yields. X-Ray crystal structures of these complexes demonstrated monomeric formulations with distorted octahedral geometry about the lanthanide(III) ions. These new complexes are thermally stable at .300 uC, and sublime without decomposition between 180-220 uC/0.05 Torr. The atomic layer deposition of Er 2 O 3 films was demonstrated using Er( t BuNC(CH 3 )N t Bu) 3 and ozone with substrate temperatures between 225-300 uC. The growth rate increased linearly with substrate temperature from 0.37 A ˚per cycle at 225 uC to 0.55 A ˚per cycle at 300 uC. Substrate temperatures of .300 uC resulted in significant thickness gradients across the substrates, suggesting thermal decomposition of the precursor. The film growth rate increased slightly with an erbium precursor pulse length between 1.0 and 3.0 s, with growth rates of 0.39 and 0.51 A ˚per cycle, respectively. In a series of films deposited at 250 uC, the growth rates varied linearly with the number of deposition cycles. Time of flight elastic recoil analyses demonstrated slightly oxygen-rich Er 2 O 3 films, with carbon, hydrogen and fluorine levels of 1.0-1.9, 1.7-1.9 and 0.3-1.3 atom%, respectively, at substrate temperatures of 250 and 300 uC. Infrared spectroscopy showed the presence of carbonate, suggesting that the carbon and slight excess of oxygen in the films are due to this species. The as-deposited films were amorphous below 300 uC, but showed reflections due to cubic Er 2 O 3 at 300 uC. Atomic force microscopy showed a root mean square surface roughness of 0.3 and 2.8 nm for films deposited at 250 and 300 uC, respectively.

We describe the use of Er(tBuNC(CH 3 )NtBu) 3 as a dopant source in the preparation of silicon nanocrystals, particularly as regards their observed structure, composition, and photophysical properties. These nanocrystals were prepared by the co-pyrolysis of Er(tBuNC(CH 3 )NtBu) 3 and disilane in a dilute helium stream at 1000 • C. Characterization methods include high resolution electron microscopy, selected area electron diffraction, energy dispersive x-ray measurements, extended x-ray absorption spectroscopy, and photoluminescence spectroscopy. In conditions identical to those used previously for β-diketonate precursors, nanocrystals doped using this amidinate source are larger in size, of a narrower size distribution, and contain more erbium in the nanocrystal on average. Steady state photoluminescence measurements as a function of excitation wavelength confirm that the characteristic 1540 nm emission detected in these nanocrystals emit by a silicon exciton-mediated pathway. These results are a clear example of precursor dopant chemistry exerting a significant effect on resultant nanoparticle properties.