Synthetic studies of aluminum and lanthanide complexes and the chemical vapor deposition of gadolinium oxide films

The synthesis of homoleptic gallium and indium alkanethiolate complexes (M(SR)3) were reported by Suh and Hoffman but the analogous aluminum alkanethiolate complexes have never been prepared. Synthetic studies to complete the group 13 series were performed resulting in the preparation of Al(SR) 3 where R = t-Bu or i-Pr. Stable amine adducts Al(SR)3(R'NMe2) where R = i-Pr or t-Bu and R' = H or Et were also synthesized. X-Ray crystallographic studies show that the homoleptic thiolates are dimeric in the solid state.; Homoleptic metal amide complexes, such as M(NR2)4 (M = Zr, Si or Sn) and Ta(NMe2)5, have been shown to be excellent precursors for the chemical vapor deposition of metal oxide films. With this as background, an attempt was made to synthesize new cerium amides for use as precursors to cerium oxide thin films. The reaction of CeCl 3(THF)2 with LiN-t-BuSiMe3 yielded Ce(N-t-BuSiMe3)3, but the complex was not thermally stable. Attempts to prepare bulky TMP derivatives (TMP = 2,2,6,6-tetramethylpiperidide) resulted in the isolation of the alkoxide-bridged dimer [Ce(TMP)2(mu-OCH=CH 2)]2 and Ce(TMP)3.; A synthetic route to gadolinium and samarium cyclopentadienyl alkoxides was developed and gadolinium oxide films were prepared from one of the new complexes by chemical vapor deposition. Reactions of Ln(Cp)3 (Ln = Gd or Sm) with i-PrMe2COH yielded Sm2(OCMe 2-i-Pr)3Cp3, [Sm(OCMe2- i-Pr)2(Cp)]2, and [Gd(OCMe2- i-Pr)2(Cp)]2. Gadolinium oxide films were deposited at 300--500°C in a low-pressure chemical vapor deposition process from [Gd(OCMe2-i-Pr)2(Cp)]2 and O2 precursors. The films were characterized by X-ray photoelectron spectroscopy and Rutherford backscattering spectrometry.