NOVELTY - Cyclopentadienyl solvent based precursor, is new.    USE - (I) is useful for atomic layer deposition (claimed), which is useful in other electronics industries, such as flat panel display, compound semiconductor, magnetic and optical storage, solar cell, nanotechnology and nanomaterials. (I) is useful: for forming high-k gate dielectric layers for silicon, germanium, and carbon based group IV elemental semiconductors or for forming high-k gate dielectric layers for indium gallium arsenide, aluminum gallium arsenide and other III-V high electron mobility semiconductors; for forming high-k capacitors for dynamic random access memory, flash and ferroelectric memory devices; and as active surfaces for gas purification, organic synthesis, fuel cell membranes and chemical detectors, and in photo electronic applications, such as laser, light amplification, light transportation, light emission, and light detection.    ADVANTAGE - (I) is oxygen-free cyclopentadienyl precursor. (I): is able to employ solid precursors for liquid solution based atomic layer deposition (ALD) processes, by low thermal budget room temperature delivery, hence overcomes thermal decomposition problems associated with standard liquid precursors; is environmentally friendly as such process requires less metal precursor in the solution systems; and allows for true ALD film growth by complete vaporization of the precursor and other reactant.    DETAILED DESCRIPTION - Cyclopentadienyl solvent based precursor of formula ((R1R2R3R4R5Cp)3M) (I), is new.    R1-R5 = H or a hydrocarbon of formula (CnHm);    n = 1-10;    m = 1-(2n+1);    Cp = cyclopentadienyl; and    M = a lanthanide or group III element.    INDEPENDENT CLAIMS are included for:    (1) a metal oxide film of formula (MyOx) (II), deposited by atomic layer deposition using the precursor comprising a metal compound of formulae ((EtCp)3M), ((iPrCp)3M) or ((nPrCp)3M) and ((tBuCp)3M) or ((BuCp)3M); and    (2) method of atomic layer deposition comprising introducing a first precursor solution having (I) dissolved in a solvent to a vaporizer; vaporizing the first precursor solution in the vaporizer; delivering the vaporized first precursor to a deposition chamber; forming a monolayer of a metal containing molecule by surface reaction on a substrate; purging the deposition chamber; introducing a second precursor comprising an oxygen containing compound, a nitrogen containing compound, or a reactive reducing compound to the deposition chamber; forming one monolayer of a metal oxide film by surface reaction on the substrate; and repeating the steps to produce a metal oxide film of predetermined thickness on the substrate.