Synthesis and characterization of novel zinc precursors for ZnO thin film deposition by atomic layer deposition

Novel Heteroleptic Tin(II) Complexes Capable of Forming SnO and SnO2 Thin Films Depending on Conditions Using Chemical Solution Deposition

A new heteroleptic complex series of tin was synthesized by the salt metathesis reaction of SnX₂ (X = Cl, Br, and I) with aminoalkoxide and various N-alkoxy-functionalized carboxamide ligands. The complexes, [ClSn(dmamp)]₂ (1), [BrSn(dmamp)]₂ (2), and [ISn(dmamp)]₂ (3), were prepared from the salt metathesis reaction of SnX₂ with one equivalent of dmamp; [Sn(dmamp)(empa)]₂ (4), [Sn(dmamp)(mdpa)]₂ (5), and [Sn(dmamp)(edpa)]₂ (6) were prepared via the salt metathesis reaction using complex 2 with one equivalent of N-alkoxy-functionalized carboxamide ligand. Complexes 1-5 displayed dimeric molecular structures with tin metal centers interconnected by μ₂-O bonding via the alkoxy oxygen atom. The molecular structures of complexes 1-5 showed distorted trigonal bipyramidal geometries with lone pair electrons in the equatorial position. Using complex 6 as a tin precursor, SnO _x films were deposited by chemical solution deposition (CSD) and subsequent post-deposition annealing (PDA) at high temperatures. SnO and SnO₂ films were selectively obtained under controlled PDA atmospheres of argon and oxygen, respectively. The SnO films featured a tetragonal romarchite structure with high crystallinity and a preferred growth orientation along the (101) plane. They also exhibited a lower transmittance of >52% at 400 nm due to an optical band gap of 2.9 eV. In contrast, the SnO₂ films exhibited a tetragonal cassiterite crystal structure and an extremely high transmittance of >97% at 400 nm was observed with an optical band gap of 3.6 eV.