(742h) Understanding and Improving the (Al,Sc)N Heterostructural Alloy through DFT Calculations and Combinatorial Synthesis
In this talk, we present a complementary theoretical and experimental investigation of piezoelectrically active nitride alloys to develop design principles and approaches for utilizing heterostructural alloying as a materials design strategy. We use ab initio methods to predict the structural and electronic properties of Al1-xScxN and Al1-x-yScxByN heterostructural alloys for the energetically competitive polymorphs and compute their corresponding equilibrium phase diagrams and materials properties. Combinatorial sputtering is employed as a non-equilibrium growth technique to overcome thermodynamic solubility limits and produce metastable thin-film samples spanning the alloy composition range. The effect of incorporation of scandium and boron into the AlN on properties including crystal structure, film texture, and piezoelectric properties is explored.
The experimentally validated predictions, theory guided combinatorial synthesis, and characterization of piezoelectric heterostructural alloys exemplify how our integrated research strategy is used to design and realize functional metastable materials. Our approach establishes a new route for the control of structure-property and composition-structure relationships by accessing non-equilibrium phase space to develop new piezoelectric materials with uniquely tailored properties for specific applications.