Synthesis of aluminium and gallium fluoroalkoxide compounds and the low pressure metal-organic chemical vapor deposition of gallium oxide films

Abstract

Aluminium and gallium fluoroalkoxide complexes of formula M(OR f ) 3 (HNMe 2 ) [M=Al or Ga; R f =CH(CF 3 ) 2 , CMe 2 (CF 3 ) or CMe(CF 3 ) 2 ] were prepared by reacting the corresponding metal dimethylamide complexes with fluorinated alcohols. The dimethylamine adducts reacted with 4-dimethylaminopyridine to give M(OR f ) 3 (4-Me 2 Npy) [M=Al or Ga; R f =CH(CF 3 ) 2 , CMe 2 (CF 3 ) or CMe(CF 3 ) 2 ]. Crystal structure analyses of Ga[OCH(CF 3 ) 2 ] 3 (4-Me 2 Npy), Ga[OCMe 2 (CF 3 )] 3 (4-Me 2 Npy) and Al[OCMe(CF 3 ) 2 ] 3 (4-Me 2 Npy) showed they have distorted tetrahedral geometries. Gallium oxide films were prepared from Ga[OCH(CF 3 ) 2 ] 3 (HNMe 2 ) and air by low-pressure chemical vapor deposition at substrate temperatures of 250-450 °C. Films deposited at 450 °C had a composition of Ga 2 O 3.1 by backscattering analysis, an optical band gap of 4.9 eV, and were >90% transmittant in the 300-820 nm region.