Gallium tris(isopropoxide) Ga(OiPr)3
Gallium isopropoxide Ga(OiPr)3 was synthesized by the reaction of [Ga(NMe2)3]2 with iPrOH yielding tetramers Ga[(μ-OiPr)2Ga(OiPr)2]3. The solution equilibrium tetramer-dimer Ga[(μ-OiPr)2Ga(OiPr)2]3 <-> 2[Ga(μ-OiPr)(OiPr)2]2 was observed (ΔH° = 8.7(0.4) kcal/mol, ΔS° = 27(1) eu (?), Δ = 0.63(0.04) kcal/mol). [472]
Gallium isopropoxide Ga(OiPr)3 has been applied as single source precursor for the growth of amorphous Ga2O3 films on Si(100) substrates by MOCVD at substrate temperatures 400-800°C. At growth temperatures 500-600°C stoichiometric Ga2O3 thin films with <3.5% C bulk contamination (by XPS) were obtained. Formation of ~20-40 nm grains on the film surfaces were observed by SEM and AFM, the rms roughness by AFM was ~1 nm. Cross-sectional TEM revealed about 3.5 nm interfacial layer between Ga2O3 and Si. Based on analysis of gaseous products of the CVD reaction by gas chromatography-mass spectrometry (GC-MS), possible CVD mechanism was proposed. [[i]]
[i] Doo Hyun Kim, Seung Ho Yoo, Taek-Mo Chung, Ki-Seok An, Hee-Soo Yoo, and Yunsoo Kim, Bull. Korean Chem. Soc. 2002, Vol. 23, No. 2 225
Gallium tert-butoxide Ga(OtBu)3 has been synthesized by reaction of [Ga(NMe2)3]2 with tBuOH at room temperature. In contrast to the preparation of Ga(OiPr)3, the bulkier OtBu ligand yielded mixtures of the dimer [Ga(μ-OtBu)(OtBu)2]2 and the amine adduct Ga(OtBu)3(HNMe2). Upon heating in an open system, the amine could be removed from Ga(OtBu)3(HNMe2) yielding corresponding homoleptic alkoxide dimer. [472]
Low-pressure CVD using [Ga(μ-OtBu)(OtBu)2]2 with O2 as an oxidant gave Ga2O3 films at substrate temperatures of 300−700°C. The as-deposited films were carbon-free, amorphous, and highly transparent in the 350−800-nm region.[54]
Synthesis of gallium isobutoxide and its application for CVD is given in the paper of Ga tert-butoxide .[54] Ga(OiBu)3 is a potential precursor for MOCVD of Ga-O containing layers.
Ga(hfip)3(NHMe2) for Ga2O3 CVD
Gallium hexafluoroisopropoxide dimethylamine complex [Ga(OCH(CF3)2)3(NHMe2)] has been applied as precursor for the growth of Ga2O3 by MOCVD [473]