Technical University of Darmstadt, Department of Materials Science, 64287 Darmstadt, Germany.
ACS Appl Mater Interfaces. 2012 Dec;4(12):6835-41. doi: 10.1021/am302004j. Epub 2012 Nov 30.
Indium zinc oxide thin-film transistors are fabricated via a precursor in solution route on silicon substrates with silicon dioxide gate dielectric. It is found that the extracted mobility rises, peaks, and then decreases with increasing precursor concentration instead of rising and saturating. Investigation with scanning probe techniques reveals full thickness variations within the film which are assumed to adversely affect charge transport. Additional layers are coated, and the extracted mobility is observed to increase up to 19.7 cm(2) V(-1) s(-1). The reasons for this are examined in detail by direct imaging with scanning tunneling microscopy and extracting electron density profiles from X-ray reflection measurements. It is found that the optimal concentration for single layer films is suboptimal when coating multiple layers and in fact using many layers of very low concentrations of precursor in the solution, leading to a dense, defect and void free film, affording the highest mobilities. A consistent qualitative model of layer formation is developed explaining how the morphology of the film develops as the concentration of precursor in the initial solution is varied.
铟锌氧化物薄膜晶体管通过在硅衬底上的硅二氧化硅栅介质中的前体溶液路线制造。研究发现，提取的迁移率随着前体浓度的增加而升高、达到峰值，然后下降，而不是一直升高并达到饱和。扫描探针技术的研究揭示了薄膜内的全厚度变化，这被认为会对电荷传输产生不利影响。额外的层被涂覆，提取的迁移率增加到 19.7cm(2)V(-1)s(-1)。通过扫描隧道显微镜的直接成像和从 X 射线反射测量中提取电子密度分布，详细研究了这种现象的原因。研究发现，当涂覆多层时，单层薄膜的最佳浓度并不理想，实际上在溶液中使用许多层非常低浓度的前体，可以形成致密、无缺陷和无空隙的薄膜，从而获得最高的迁移率。开发了一个一致的定性模型来解释薄膜的形态如何随着初始溶液中前体浓度的变化而发展。
