Center Highlights

The highlights here document the progress and impact of scientific research within the Center for Next Generation of Materials by Design. Most of these highlights are associated with published journal articles by our principal investigators.

Transmission electron micrograph of epitaxial Mg0.25Ca0.75O on indium aluminum nitride. Image is gray background with rows of light-colored dots, with blue-dashed box around a section of the image, including 'indium aluminum nitride' label and 2-nanometer length scale.

ALD Oxides for Higher Performance Power Transistors PDF (February 2017)

Successfully grew single-crystalline (Mg,Ca)O films epitaxially on InAlN transistors with unprecedentedly low density of defects and electron traps at the oxide/semiconductor interface.

Circular image with hexagonal orange pattern on dark background. Large orange dots at apices of hexagon and smaller orange/yellow ovals inside of hexagon. Vertical color scale from 2.0 to 4.5 to right of circle.

Structure Property Relationships in Wide-Gap Gallium Oxide Thin Films PDF (January 2017)

Successfully determined the synthesis space (substrate temperature, oxygen partial pressure, substrate selection) for the targeted growth of β-Ga2O3 thin films through theory-guided experiments. Grew high-quality, oriented β-Ga2O3 films.

Chart of Median Lattice Cohesive Energy vs Energy above Ground State, showing 11 horizontal bars of varying length and color (Groups V, VI, and VII)

The Thermodynamic Scale of Inorganic Crystalline Metastability PDF (Dec 2016)

Revealed the thermodynamic landscape of inorganic crystalline metastability. Proposed principle of Remnant Metastability: "Observable metastable phases are remnants of thermodynamic conditions where they were once the lowest free-energy phase."

Illustration of film/base layer/substrate stack with light wave incident on top of stack from the right and emitted electron going toward detector to the left.

Accelerated in-situ Photo-Electron Spectroscopy for Materials by Design PDF (Nov 2016)

Characterized the interfacial electronic band alignment using new high-throughput measurements by coupling spatially resolved photoelectron spectroscopy (PES) mapping with combinatorially deposited crossed-gradient thin-film samples.

Plot of intensity versus Q, showing two curves that generally slope downward from the upper left to the lower right, with one spike upwards in the middle of the slope.  One curve is for a 2-hertz sample and the other curve is for a 10-hertz sample.

Local Amorphous Structure Controls Polymorph Formation PDF (October 2016)

Used grazing incidence X-ray scattering measurements to identify local structural differences in amorphous thin-film precursors that subsequently determine the polymorph formed upon crystallization.

Block diagram with blue layer over red layer and labels indicating energy sources.

Epitaxial Polymorph Stabilization through a Computational Approach to Substrate Selection PDF (May 2016)

Developed a computational framework combining calculations of formation energy, elastic strain energy, and topological lattice matching to guide substrate selection for epitaxial materials growth.

Graphic of energy on y axis and reaction coordinate on x axis. Chart, labeled Nitrides, shows two deep troughs in left and central and one higher shallow trough in right section of chart. Dotted red arrow goes from left deep trough to central deep trough. Solid red arrow goes from right shallow trough to central deep trough.

Design of Nitride Semiconductors for Solar Energy Conversion PDF (April 2016)

We provide a new perspective on the promising properties, unexplored chemistry, and metastable character of nitride semiconductors for solar energy conversion.

Pyrolusite polymorph

MnO2 Polymorph Energetics — A Unique Theoretical Challenge PDF (March 2016)

Through a collaboration with the Center for Computational Design of Functional Layered Materials EFRC, we have established that the new, non-empirical, SCAN (Strongly Constrained and Appropriately Normed Semilocal Density Functional) exchange-correlation functional for density functional theory provides a uniquely accurate first-principles model of polymorph energetics and properties.

Crystal diagram of bismuth triiodide, with bismuth as smaller blue circles and iodine as larger purple circles. Each bismuth atom is surrounded by five iodine atoms.

Bismuth Triiodide (BiI3) – A Candidate Photovoltaic Absorber PDF (December 2015)

We identified BiI3 as a candidate photovoltaic absorber using computational design criteria based on the methyl ammonium lead iodide perovskites. Initial experiments demonstrate room-temperature photoluminescence with application-relevant lifetimes.

Ball-and-stick figure for rutile, with several central green balls (titanium plus-3 charge complex) surrounded by smaller red (oxygen atom) and gray (titanium atom) balls.

Transition Metal Oxide Semiconductors PDF (Sept 2015)

Comprehensive assessment of semiconducting transition metal oxides using unbiased electronic structure calculations with integrated treatment of s, p, and d electrons.

Plot of potential energy surface with each polymorph (P0 through P5) having its own basin of attraction.

Predicting Polymorphism in Partially Ionic Solids PDF (Aug 2015)

We developed a theoretical approach to search for new and realizable metastable polymorphs in ionic systems.

Triangular diagram of s-orbital versus p-orbital versus d-orbital fraction at valence band maximum.

Identifying Defect-Tolerant, High-Lifetime Semiconductors PDF (May 2015)

The key role that band-edge orbital character has on defect tolerance (gained from MAPbX3 perovskites) underlies a new joint data-mining and theory approach to screen materials for long minority-carrier lifetimes, which is a critical photovoltaic absorber property.

Optical properties of Sn3N4, showing three curves (experiment, theory without excitons, and theory with excitons) on plot of absorption coefficient vs energy.

Semiconducting Metastable Sn3N4 and IV3N4 Polymorphs PDF

Thin films of the metastable spinel γ-Sn3N4 were synthesized by sputtering and characterized for semiconducting properties, such as absorption spectra, electrical transport, ionization potential, and minority-carrier diffusion length.

Plot of enthalpy versus AX compounds.

The Center for Next Generation of Materials by Design: Mission and Research PlanPDF

The mission of the Center for Next Generation of Materials by Design is to dramatically transform the discovery of functional energy materials through multiple-property search, incorporation of metastable materials into predictive design, and the development of theory to guide materials synthesis.

Polymorph Sampler will add not-yet-discovered polymorphs to Materials by Design.

Incorporating Metastable Polymorphs into Materials by DesignPDF

The Center for Next Generation of Materials by Design is creating a high-throughput computational tool based on first-principles theory to predict the formation energy of polymorphs, including new unknown structures.

Plot of temperature (0 to 2000 K) versus MnZnO stoichiometry (x = 0 to 1). Five regions on plot.  Red, "RS": downward-tapering wedge along left side. Blue, "WZ": downward-tapering wedge along right side. Light red, "RS(ne)": keystone-shape at lower left. Light blue, "WZ(ne)": keystone-shape at lower right. White, "RS+WZ": remaining upper-central region.

Design of Semiconducting Tetrahedral Mn1-xZnxO Alloys PDF

The Center for Next Generation of Materials by Design is designing a novel semiconducting transition metal oxide alloy with absorption in the visible and with favorable electron and hole transport properties.