Synthesis of thin films with highly tailored microstructures

Abstract

We report a new methodology to synthesize thin films with exceptional microstructural control via systematic, in-situ seeding of nanocrystals into amorphous precursor films. When the amorphous films are subsequently crystallized by thermal annealing, the nanocrystals serve as preferential grain nucleation sites and control their micro/nanostructure. We demonstrate the capability of this methodology by precisely tailoring the size, geometry and spatial distribution of nanostructured grains in structural (TiAl) as well as functional (TiNi) thin films. This synthesis methodology is likely to be applicable to other amorphously grown materials and enables explicit microstructural control in a wide spectrum of thin films/coatings. IMPACT STATEMENTThis paper describes a novel synthesis methodology to precisely tailor the microstructure of thin films and reveals the mechanisms underlying this methodology using in-situ TEM annealing experiments. ARTICLE HISTORY

Formation and morphology of closed and porous films grown from grains seeded on substrates: Two-dimensional simulations

“…Neverthless, films in the submicron scale can be grown by seeding nanometer scale diamond grains, known as nanodiamonds [26][27][28], on substrates prior to growth [29][30][31]. The presence of seeded grains before growth is not only beneficial for decreasing film thickness but can also facilitate the growth of films with desirable morphologies and properties [32]. Moreover, altering the size of seeded nanodiamonds is known to strongly impact the morphology and thermal properties of gallium nitride (GaN) on PCD wafers [33] and PCD on GaN wafers [34].…”

Synthesis of Heterostructured Metallic Films with Precisely Defined Multimodal Microstructures

“…Heterostructured materials, which are composed of domains that vary in size from a few nanometers to several micrometers, encompass a wide range of microstructural designs including multimodal microstructures, gradient microstructures, − harmonic structures, and hierarchical microstructures. , These materials have been synthesized through a variety of processing routes such as thermomechanical treatment of cold worked metals, severe plastic deformation and sintering of powders, , surface mechanical attrition/grinding treatment, , and electrodeposition . A common feature that links the different manifestations of heterostructured materials is the presence of domains with contrasting properties that synergistically interact to produce desirable property combinations.…”