Department of Chemistry, Donnan and Robert Robinson Laboratories, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK.
Inorg Chem. 2011 Nov 21;50(22):11644-52. doi: 10.1021/ic201593s. Epub 2011 Oct 21.
Thin films of ceria (CeO(2)) have many applications, and their synthesis by liquid-injection MOCVD (metal-organic chemical vapor deposition) or ALD (atomic layer deposition) requires volatile precursor compounds. Here we report the synthesis of a series of homoleptic and heteroleptic Ce(IV) complexes with donor-functionalized alkoxide ligands mmp (1-methoxy-2-methylpropan-2-olate), dmap (1-(dimethylamino)propan-2-olate), and dmop (2-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)propan-2-olate) and their potential as precursors for MOCVD and ALD of CeO(2). New complexes were synthesized by alcohol exchange reactions with [Ce(OBu(t))(4)]. [Ce(mmp)(4)] and [Ce(dmap)(4)] were both found to be excellent precursors for liquid-injection MOCVD of CeO(2), depositing high purity thin films with very low carbon contamination, and both have a large temperature window for diffusion controlled growth (350-600 °C for [Ce(mmp)(4)]; 300-600 °C for [Ce(dmap)(4)]). [Ce(mmp)(4)] is also an excellent precursor for liquid-injection ALD of CeO(2) using H(2)O as oxygen source and demonstrates self-limiting growth from 150 to 350 °C. [Ce(dmap)(4)] has lower thermal stability than [Ce(mmp)(4)] and does not show self-limiting growth in ALD. Heteroleptic complexes show a tendency to undergo ligand redistribution reactions to form mixtures in solution and are unsuitable as precursors for liquid-injection CVD.
氧化铈（CeO(2)）薄膜有许多应用，其通过液体注射 MOCVD（金属有机化学气相沉积）或 ALD（原子层沉积）合成需要挥发性前体化合物。在这里，我们报告了一系列同核和杂核 Ce(IV)配合物的合成，这些配合物具有给体官能化的烷氧基配体 mmp（1-甲氧基-2-甲基-2-丙醇）、dmap（1-(二甲基氨基）-2-丙醇）和 dmop（2-(4,4-二甲基-4,5-二氢恶唑-2-基）-2-丙醇），并探讨了它们作为 MOCVD 和 ALD 合成 CeO(2)前体的潜力。新的配合物是通过醇交换反应与[Ce(OBu(t))(4)]合成的。发现[Ce(mmp)(4)]和[Ce(dmap)(4)]都是 CeO(2)液体注射 MOCVD 的优秀前体，沉积出高纯薄膜，且碳污染极低，扩散控制生长的温度窗口很大（[Ce(mmp)(4)]为 350-600°C；[Ce(dmap)(4)]为 300-600°C）。[Ce(mmp)(4)]也是使用 H(2)O 作为氧源的 CeO(2)液体注射 ALD 的优秀前体，在 150-350°C 之间表现出自限性生长。[Ce(dmap)(4)]的热稳定性低于[Ce(mmp)(4)]，且在 ALD 中不表现出自限性生长。杂核配合物倾向于发生配体重排反应，在溶液中形成混合物，不适合作为液体注射 CVD 的前体。
