Probing the Atomic-Scale Structure of Amorphous Aluminum Oxide Grown by Atomic Layer Deposition

• DOI: 10.1021/acsami.0c01905
• Publication Date: 2020-04-20T15:42:51Z
• Authors: Matthias J. Young; Nicholas M. Bedford; Angel Yanguas-Gil; Steven Letourneau; Matthew Coile; David J. Mandia; Bachir Aoun; Andrew S. Cavanagh; Steven M. George; Jeffrey W. Elam
• Keywords: Atomic units; Deposition

Atomic layer deposition (ALD) is a well-established technique for depositing nanoscale coatings with pristine control of film thickness and composition. The trimethylaluminum (TMA) water (H2O) ALD chemistry inarguably the most widely used yet to date, we have little information about atomic-scale structure amorphous aluminum oxide (AlOx) formed by this chemistry. This lack understanding hinders our ability establish process-structure-property relationships ultimately limits technological advancements employing AlOx made via ALD. In work, employ synchrotron high-energy X-ray diffraction (HE-XRD) coupled pair distribution function (PDF) analysis characterize atomic coatings. We combine ex situ in operando HE-XRD measurements on fit these experimental data using stochastic structural modeling reveal variations Al-O bond length, Al O coordination environment, extent vacancies as growth conditions. particular, local found change substrate number cycles. observed trends are consistent formation bulk Al2O3 surrounded an O-rich surface layer. deconvolute both phases. Overall, work demonstrates usefulness PDF improving thin films provides pathway evaluate how process changes impact properties films.