Jon-Paul Maria Research Group


NCSU Department of Materials Science and Engineering
Summary of Active Externally Funded Programs
ACTIVE COLLABORATORS FROM EXTERNAL INSTITUTIONS
Igal Brener
William Luk
Stefano Curtarolo
Patrick Hopkins
Beth Opila
Jon Ihlefeld
David Peters
Colin Freeman
Dana Dlott
Jeremy Levy
Ken Vecchio
Jian Luo
Oleg Prezhdo
Sanjay Krishna
Overview of Maria Group Primary Programs
Extreme-High Mobility Oxides
for Plasmonic Structures and
Devices in the Midwave and
Longwave IR Spectrum
Hetero-polar and
Heteroepitaxial Interfaces for
Emergent Interfacial Properties
and Function
New Materials and New
Properties Discovery through
Entropic Stabilization
Nanoenergetic Materials for
Advanced Combustion Science,
Safety, and Defence
Applications
Active support from: ARO MURI, NSFCHE, DOE, and DARPA
Active support from: NSF-DMR
Active Support from: ONR-MURI and
NSF-DMR
Active support from: ARO-MURI and
ARO-Combustion
Summary: Since 2014 the Maria Group
has been studying CdO as a gateway
material for IR plasmonic devices. The
combination of high mobility and high
carrier density enable it to sustain sharp
low loss plasmon polaritons in the midand long-wave IR.
Summary: The Maria Group is exploring
interfaces between oxides and nitrides
with the intent to create structures that
exhibit the structural and chemical
perfection of semiconductors like Si and
GaAs. We anticipate emergent properties
from these interfaces that originate from a
high-mobility two-dimensional electron
gas. The interface properties should be
comparable to those observed in epitaxial
oxide stacks like SrTiO3|LaAlO3, except
they will be observable at room
temperature.
Summary: Examples where technology
capability are materials-limited are
abundant and the materials research
community needs additional avenues to
imagine and design new ones.
Summary: The Maria Group has been
working with ARO to explore fundamental
materials science underlying chemical
energy storage and energy release in
thermite nanlaminates to inform and
improve nanoenergetic materials.
There is currently tremendous excitement
regarding the potential to make imagers,
chemical-specific sensors, and light
emitters using epsilon-near-zero (ENZ)
modes that are unencumbered by the
extreme lithography requirements in
metallic structures.
We are collaborating with and supplying
materials to researchers at Sandia, UVA,
USC, Sheffield, and ARL to pursue exciting
science and technology opportunities.
Using the principles of thermodynamics,
crystal chemistry, transport properties,
and phase equilibria, we are developing
better models to predict and engineer
energy release. This is enhanced further by
physical vapor deposition methods to
control physical geometries, i.e., diffusion
distance, at the nanometer scale.
The Maria Group is actively exploring the
concept of entropic stabilization fivecomponent oxides, carbides, and nitrides
to serve this discovery process
Two capabilities unique to the Maria and
Sitar Groups enable these structures: 1)
surfactant assisted epitaxy, and 2) stepfree GaN. The Maria and Sitar groups at
NCSU are positioned to overcome long
standing challenges to heteroepitaxial
integration.
Building upon the recent demonstration
of true entropic stabilization, we are
exploring the entropy landscape for new
ferroelectrics, new crystals with ultra-low
thermal transport, and for a new class of
extreme
high-temperature
carbide
refractories. In addition, we are exploring
on
a
fundamental
level
how
configurational entropy can influence
crystal chemistry and structure.
Most recently, we initiated collaborations
with UIUC and UVA to implement ultrafast laser tools to monitor oxygen
exchange reactions to understand the
relationship between mechanisms a short
(ns) and long (ms) time scales.
Overview of Maria Group Support
Extreme-High Mobility Oxides for Plasmonic Structures and Devices in the Midwave and Longwave IR Spectrum
ARO
MURI: Multi-modal Energy Flow at Atomically Engineered Interfaces (50%)
W911NF-16-1-0406
PI
DARPA
Polaritonic Hot-electron Infrared Photodetector (PHIP) at the Wafer Scale
Contract in progress
PI
DARPA
Extreme Mobility CdO For IR Devices
W911NF-16-1-0037
PI
DOE
Preparation Of Oxide Plasmonic Films And Investigation Of Gating Methods
DOE/Sandia 1643352
PI
NSF
Materials Development for Mid-Infrared Plasmonic Applications
NSF CHE-1507947
co-PI
Hetero-polar and Heteroepitaxial Interfaces for Emergent Interfacial Properties and Function
NSF
Emergent Phenomena at Flat Interfaces between Nitrides and Oxides
NSF DMR-1508191
PI
New Materials and New Properties Discovery through Entropic Stabilization
ONR
MURI: The Science of Entropy Stabilized Ultra-High Temperature Materials
N00014-15-1-2863
co-PI
NSF
Entropy Stabilized Complex Oxides
NSF DMR-1610844
PI
ONR
DURIP: Acquisition of High Throughput X-ray Optics
N00014-16-1-3008
PI
Nanoenergetic Materials for Advanced Combustion Science, Safety, and Defense Applications
ARO
MURI: Multi-modal Energy Flow at Atomically Engineered Interfaces (50%)
W911NF-16-1-0406
PI
ARO
DURIP Advanced Multilayer Physical Vapor Deposition Tool
70069-EG-RIP
PI
ARO
Rational Engineering of Reactive Nanolaminates for Tunable Ignition and Power
W911NF-13-1-0493
PI
ARO
RI: Instrumentation up-fit for Reactive Nanolaminate PVD
W911NF-16-1-0077
PI
Additional Programs
NSF
IRES: U.S. - Australia International Research Experience for Students:
NSF IIA-1357113
co-PI
NSF
I/UCRC Multi-University I/UCRC for Dielectrics and Piezoelectrics
NSF IIP-1361503
co-PI
MURI: Multimodal Energy Flow at Atomically Engineered Interfaces

In 2016 Jon-Paul Maria was awarded as PI an ARO MURI that explores the
energy transduction, decay, and absorption events at interfaces which are
excited to extremely high energy non-equilibrium states;

The MURI team consists of Jon-Paul Maria (NCSU), Don Brenner (NCSU),
Gregory Parsons (NCSU), Patrick Hopkins (UVA), Dana Dlott (UIUC), and
Oleg Prezhdo (USC);

Maria and Parsons are responsible for synthesis. Maria is responsible for
preparing multi-layer reactive nanolaminates (i.e., thin film thermites) and
plasmonic heterostructures while Parsons is responsible for designing and
preparing hybrid metalorganic/inorganic hetero-layers; 
Dana Dlott uses ultra-fast laser shock spectroscopy to generate mechanical
shock waves that trigger a material response, such as molecular vibrations,
or interfacial reactions. Ultrafast spectroscopy is used to monitor the
response from nanoseconds to microseconds; 
Patrick Hopkins leads the effort to apply ultrafast spectroscopy to measure
heat flow in plasmonic heterostructures and reactive laminates. TDTR based
techniques create extreme rapid thermal transients then measure ensuing
thermal transport of materials and interfaces with the ability to separate
lattice and electron temperatures in ps to ms timescales; 
Brenner leads efforts in multiscale modeling with particular interest in
monitoring the energy release at thermite interfaces with models that link
molecular modeling, first principles thermodynamics and multiscale
atomistic and continuum methods; 
Prezhdo leads the effort in density functional theory modeling, with
particular interest in non-equilibrium phenomena. Specific attention is paid
to predicting and understanding hot carrier dynamics and relaxation
processes, particularly at short time scales after an excitation event before
the carrier temperature and the lattice temperature have time to
equilibrate. Ralph Anthenien
Robert Mantz
IR Plasmonics: Quantifying Hot Carrier Injection and Decay

A substantial component of the Maria Group ARO MURI activity is a close
collaboration with the Hopkins Group at UVA through which we intend to
quantify hot carrier injection from a plasmonic host to an adjacent insulator; 
Hot carrier injection is a topic of particular interest in the optoelectronics
community, particularly in the IR, given implications on detection, heat
scavenging, and assisted catalysis. The underpinning experiment is as
follows: 
We will create a plasmonc layer that supports a sharp epsilon-near-zero
(ENZ) mode that forms a Schottky barrier to an adjacent semiconductor.
The bottom panel to the right shows reflected light spectroscopy for a
series of F-doped CdO thin films where the reflectance dip corresponds to
the ENZ energy, the entire midwave spectrum can be accessed; 
This mode will be optically driven by a tunable IR laser (Hopkins) to create
discrete and intense plasmon excitation events. After excitation, the
plasmon will decay, and can do so by phonon generation, by injecting a hot
carrier over the Schottky barrier, or a combination of both; 
Time Domain Thermoreflectance (TDTR) will be measured on the top
surface, opposite the IR excitation laser. By measuring the thermal transport
and interface scattering within this stack, it will be possible to model
changes in carrier density as a function of time, i.e., carrier injection to the
semiconductor will modulate thermal transport; 
Simultaneously, we will measure current across this stack as an additional
probe of carrier injection; 
We know from preliminary dc measurements that photo-currents are
generated in these stacks upon illumination with a 4.4 micron laser. There
is strong potential to produce several high-impact publications; 
Support ARO W911NF-16-1-0406. Extreme-High Mobility Donor-Doped Cadmium Oxide

The Maria Group has been exploring donor doped CdO consequent to its
ability to support extreme-high mobility values at carrier densities in the
range between 1e19 and 5e20;

Such mobility values can be achieved by understanding and engineering
the defect chemistry, specifically by using Fermi level control via doping to
suppress unwanted intrinsic defect formation;

With correct doping, crystal structure, and synthesis it is possible to make
CdO with carrier density values through the mid 1019cm-3 range with
mobility values >450 cm2/V-s;

This is a particularly interesting range because it enables one to support
low loss plasmon polaritons (both surface plasmon resonance and coupled
modes) through the mid-wave and long-wave IR spectra;

With CdO it is possible to create surface plasmon polariton sensors, perfect
absorbers and thermal emitters throughout the IR spectrum;

These materials have generated substantial interest in the IR optoelectronic
and the nanophotonics community;

Currently, the Maria Group has an oxide MBE and two sputtering tools
dedicated to CdO and CdO-device synthesis;

Our group developed plasma-enhanced MBE and pulsed dc sputtering
methods for CdO;

We currently prepare extreme mobility CdO on a variety of epitaxial and
polycrystalline surfaces with well-controlled morphology;

Currently we provide CdO thin films to 4 groups worldwide and we are
collaborating with researchers from Sandia National Laboratories, Duke
University, NCSU, Northwestern, and Sheffield on the interesting
possibilities for next generation IR technologies;

Support: DARPA: Extreme Mobility Cdo For IR Devices W911NF-16-1-0037.
Active Plasmonic Devices Based on ENZ Modes

The Maria Group has been collaborating with the Teams of Igal Brenner
and David Peters at Sandia National Laboratories to explore epsilon-nearzero modes, which are an extreme sub-wavelength plasmon polariton
excitation in films much thinner than the skin depth;

The ability to tune CdO ENZ modes throughout the entire longwave and
midwave IR spectrum make this an ideal material from which to design
perfect absorbers without lithography. These experiments cannot be done
with conventional metals;

We are conducting experiments that attempt to quantify the light coupling
to ENZ modes. By creating a plasmonically active thermocouple we can
meausure the temperature rise from a perfect plasmonic absorption event;

CdO thin films give us a unique opportunity to do this in the simple
configuration of an epitaxial CdO homojunction as illustrated in the upper
left;

The bottom film is doped to 7x1019 cm-3, at this carrier density the
plasmonic mode is 4.4 microns, and one can couple to it optically. The top
CdO has ne ~ 1x1019 cm-3, this carrier difference produces a large work
function shift thus creating a junction emf;

We illuminate the device with a 4.4 micron laser and measure voltage as a
function of polarization orientation, only p-polarized can couple a voltage
increase is clearly evident for this orientation and not the other;

These preliminary data allow us to relate CdO heating to plasmon
absorption since the entire stack is transparent to 4.4 micron radiation.
These are exciting experiments that the nanophotonics community has
been attempting in patterned systems. CdO provides unique and
convenient access to these fundamental phenomena;

Support: DOE Sandia National Labs 1643352.
Oxide-Nitride Heterostructures with Flat Interfaces

Our Group is creating oxide-nitride interfaces with structural and chemical
perfection that is typically reserved for lattice-matched systems such as
arsenide-arsenide, nitride-nitride, or perovskite-perovskite stacks;

We are interested in the oxide-nitride case where heteropolar
heterojunctions host a tunable and reconfigurable 2-dimensional electron
gasses (2DEG);

In the ideal situation, one creates a heterojunction with a polar discontinuity
between GaN and a wider band gap functional polar oxide. The direction
of the band gap change and the polarity change would promote a 2DEG in
the GaN which can be modulated by the oxide non-linear properties;

In the context of oxide-oxide polar heterojunctions, the oxide nitride case
represents a major step forward since, in principle, the 2DEG that resides in
the GaN would exhibit very high mobility at room temperature, instead of
requiring cryogenic conditions, as with perovskite systems;

10 years of research positions our group as a world leader in fabrication
and testing such structures. Essential advances include surfactant-assisted
epitaxy of oxides, and nitride planarization. These allow us to grow
commensurate lattice matched oxides on GaN surfaces that contain no
atomic steps over 100s of microns. These are two requisite capabilities
present only at NCSU;

We are currently preparing structures as shown in the upper right panel
where one can modulate transport at perfectly flat interfaces. When
successful, we will have bridged the high channel mobility, at room
temperature, of a GaN 2DEG with the nonlinear properties of oxides;

The ultimate intent is to create 2-dimensional lateral junctions that can be
re-configured/re-written by re-oreintable ferroelectric domains;

Support: NSF DMR-1508191.
Entropy-Stabilized Oxides

In 2014, inspired by the structural metallurgy community, our group began
exploring the concept of new materials development by entropic
stabilization of many-component complex oxides;

The alloy research community had been using this approach to create new
formulations with interesting mechanical properties, however, there was no
clear evidence that entropy was indeed the stabilizing factor, in fact, most
data suggested otherwise;

Using a thermodynamic approach involving phase diagram mapping
temperature dependent XRD, calorimetry, STEM, and XAFS, our group
showed that five component oxides could be stabilized by configurational
entropy. The first formulation is J14 – Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O, which
transforms to single phase rocksalt at ~ 875 oC

This fundamental demonstration of entropic stabilization opens a new
landscape for materials design and the potential for new structure-property
relationships in crystalline materials. Fundamentally, we know that with
configurational entropy, we can promote cation occupancy in oxygen
polyhedra that are otherwise extremely unusual;

The research is extremely exploratory at this stage, but already we see
interesting trends that are highly unusual and perhaps without precedent.
Specifically, using thin film approaches, where we can expand dramatically
the range of entropy-stable compositions, we observe very interesting
interplay between a high entropy host that accommodates an aliovalent
cation. It appears that the systems prefer structural distortions and charge
transfer between the cations as opposed to point defect creation;

The Maria Group is working in close collaboration with the groups of
Donald Brenner and Stefano Curtarolo (NCSU and Duke) who are exploring
first principles simulations to understand these structures;

Support: NSF DMR-1610844.
MURI: The Science of Entropy Stabilized Ultra-High
Temperature Materials

Professor Donald Brenner is PI of an ONR MURI that explores the science
of entropy stabilized ultra-high temperature materials in an effort to create
new materials that operate at T > 2500 0C;

The MURI team includes D. Brenner and J-P. Maria (NCSU), S. Curtarolo
(Duke), E. Opila and P. Hopkins (UVA), K. Vecchio and J. Luo (UCSD);

The concept of extreme-high temperature materials was proposed by
Maria and Brenner via the argument that melting point is determined by
the disorder gained when transitioning to the liquid phase and the internal
energy of the melting crystal. If a five-component solid is comprised of
refractory cations that are randomly distributed among a single sublattice,
the Smelting falls and in turn, TM should elevate. Testing this basic hypothesis
and preparing high entropy and entropy-stabilized carbides and nitrides
are activities of this program;

The Brenner Group is responsible for multiscale modeling of the materials
response to extreme high temperatures and to oxidizing environments;

The Curtarolo Group leads high-throughput simulations to predict entropystablized formulations and the structures they adopt;

The Maria Group leads a thin film effort to fabricate high-purty and highdensity 5-component carbides using multiple magnetron sputtering;

At UVA, the Hopkins Group leads an effort to measure and understand
thermal transport in these new phases, particularly at T > 2000 0C, while
Opila leads the effort to characterize high temperature oxidation;

Ken Vecchio and Jian Luo at UCSD lead efforts to fabricate and characterize
bulk materials predicted by Curtarolo from the carbide and boride systems
respectively;

Support: ONR N00014-15-1-2863.
Eric Wuchina
Kenney Lipkowitz
Entropy-Stabilized Carbides by Reactive Co-sputtering

The Maria Group is preparing 5-component metal carbides and nitrides to
explore the opportunities for entropic stabilization in these extreme
refractory systems;

The experimental work is closely coupled to high-throughput predictions
of the Curtarolo Group to advance our predictive powers for new phases,
and the extent to which these phases could be preserved at room
temperature in the metastable state;

In addition, the same validation experiments are needed for the highthroughput thermodynamic calculations by the Vecchio Group at UCSD;

Step one in this process was constructing a co-sputtering system that could
rapidly screen composition space, creating materials with high density and
high purity – both are often challenging using bulk methods given the
extreme refractoriness of the chemical constituents;

The upper right panel shows a 5-component reactive co-sputtering tool
built in the first program year. It features five two-inch magnetrons that can
be driven simultaneously. Sputtering from refractory metal targets can be
performed in methane to create carbides or nitrogen to create nitrides. The
system has a substrate manipulator capable of 1000 0C to facilitate phase
formation;

Recent results show that single phase rocksalt can be achieved in the mixed
carbide: Hf0.2Nb0.2Ta0.2Ti0.2W0.2C. This is an interesting result considering that
WC prefers a hexagonal structure until 2500 0C. Tests are ongoing to
determine the driving forces for stabilization and many other formulations.
X-ray diffraction data for this 5-component system is shown;

In addition to the 5-component mixed carbides, we are also preparing high
temperature metal transducers in collaboration with the Hopkins Group.
We are developing process flows for Ir, TaC, and HfN so that TDTR can be
extended to a temperature range above 2000 0C;

Support: ONR N00014-15-1-2863.
Energetic Nanomaterials: Analysis by Laser-Shock Spectroscopy

A second component to the Maria Group MURI activity is exploring
interface reactions of reactive nanolaminates that are exposed to extreme
mechanical loading; 
The interest is to understand how the reaction evolves over time from local
transport a few atomic distances from the interface to long scale transport
over the entire sample volume, i.e., 100s nm. We wish to answer a few
fundamental questions, for example, what is the true driving force for
reaction; forming the terminal metal oxide, or initial dissolution of oxygen
into the reactive metal? Do these change with time? 
The Maria Group prepares two and three-component laminates using
magnetron sputtering, which are analyzed by the Dlott Group at UIUC via
laser-driven flyer plates. As illustrated below, flyer plates impact the
substrate of a thermite stack sending a shock wave to initiate interactions; 
IR and visible spectroscopy are recorded as a function of time after initial
impact. Information regarding reactions, molecular vibration, and heat
emission is collected in the range of nano- to miliseconds; 
Support ARO W911NF-16-1-0406.
Energetic Nanomaterials: Eutectic Engineering of Energy Release

In addition to the MURI, the Maria Group has a companion program in
nanoenergetic materials where oxygen exchange in metastable metalmetal oxide thin film stacks is under exploration;

Specifically, we are trying to understand how the structural and physical
properties of the constituent materials and their phase equilibria can be
used to create a predictive framework to understand the mechanisms of
energy release;

The work is conducted in close collaboration with the Brener Group at
NCSU who uses multiscale modeling to develop a more sophisticated
understanding of our experimental findings. Recently, Brenner developed
a virtual calorimeter model to simulate the heat output of a reactive
laminate stack and a modified Kissenger analysis to normalize for physical
dimensions. Agreement between models and experiment are excellent;

This combination of experiment and simulation helped us identify and
explain a new method to understand the predominant driving force in
some systems, which is the development of a low eutectic temperature
intermetallic phase;

The upper right figure is calorimetry data for Al|CuO stacks as a function of
interface density, all samples constant total thickness. Between 4 and 5
bilayers there is an abrupt drop in the temperature of the first exotherm.
This corresponds to the lowest temperature eutectic in the Al-Cu system,
and it appears to trigger the oxygen exchange process via liquid transport;

To occur, metallic Al must come into contact with metallic Cu, which
suggests that oxygen dissolution from CuO into Al may be most important
at the early stages of reaction;

This suggests a completely new way to engineer reactions, i.e., by
introducing interfacial precursors to promote transport at a specific
temperature;

Support: W911NF-13-1-0493.
Ceramic Densification at Extreme-Low Temperatures

Through the NCSU-PSU Center for Dielectrics and Piezoelectrics, the Maria
Group is researching the possibility to densify refractory ceramics at
extreme-low temperatures using a combination of hydrothermal growth
and uniaxial pressure;

While the origins of this method can be found in publications from the
Yamazaki Group at the University of Koichi in the mid 1980s, it took ~30
years for researchers at the University of Oulu and Penn State to extend the
method to technical ceramics and demonstrate that density values in
excess of 95% can be achieved at temperatures well below 300 0C;

In a companion effort to the Randall Group at Penn State, the Maria Group
is exploring the fundamental mechanisms of hydrothermal densification
under uniaxial pressure in binary oxides. By understanding the specific
modes of mass transport, it should be possible to expand the number of
oxides, and possibly beyond, that can be cold sintered to near full density;

To date, our research shows that absent strong capillary forces in extremely
soluble systems like NaCl, cold sintering pressures are established by
volume expansion of the solvent;

Experiments suggest that the propensity for molecule exchange to and
from the cations ligand field has an important influence on the rates of
mass transport. While challenging, it appears that if one could regulate
ligand lability the number of compositions that could be cold sintered to
full density at low temperatures could be expanded dramatically;

With this learning, The NCSU team has been able to prepare ZnO, WO3,
MnO, Li2MoO4, and SnO to density values > 95%. In ZnO, high resolution
STEM shows that grain boundaries in ZnO are clean and highly crystalline;

Currently, we are developing instrumentation to automate the cold
sintering process by incorporating strain control and automatic pressure
regulation;

Support: NSF I/UCRC 1361503.
Entrepreneurship and Commercialization

In January, 2017 Jon-Paul Maria, Edward Sachet, and Christopher Shelton
co-founded Third Floor Materials;

Edward Sachet is President, Jon-Paul Maria is Chief Technical Officer, and
Christopher Shelton is Chief Financial Officer;

Third Floor Materials has exclusive license to two pending NCSU-owned
patents that are based on the Maria Group research in high-mobility
cadmium oxide thin films;

Third Floor Materials endeavors to create optoelectronic devices that
operate in the mid-IR spectrum. The high mobility and intense plasmonic
activity of CdO makes it an ideal material for detectors, emitters, sensors,
and imagers with the ultimate goal of devices that operate without
cryogenic cooling;

Third Floor Materials is current supported by two programs, an Air Force
STTR and a DARPA collaborative contract. Maria is the NCSU PI of the STTR
and the PI of the DARPA program.