IRG-2 aims to deliver "Materials for AI" by designing hybrid ionic/electronic conductors (HIECs) based on organic materials and inorganic layered materials that mimic biological neuronal behaviors with broad implications for neuromorphic computing, bioelectronics, and energy storage technologies. By undestanding and leveraging spatiotemporal cooperativity of electronic and ionic processes, IRG-2 will realize neuron-inspired phenomena in HIECs such as adaptive synaptogenesis, sensory transduction, tunable potentiation/plasticity, and optogenetic responses.

IRG 1 investigates mobility in glasses and supercooled liquids using nanoscale, time-resolved experiments and machine learning. By understanding viscosity, fragility, and relaxation, the group aims to predict glass properties and design advanced materials, including organic semiconductor films for electronics and stabilized drug molecule glasses for pharmaceuticals.

The Materials Research Science and Engineering Center (MRSEC) known as the Center for Materials Research (CMR) at Stanford University supports research over a wide area of materials science, with a strong emphasis on providing support through shared facilities for the materials community at and around Stanford University, including industry. The research program is organized in three interdisciplinary research groups. Investigators in the group concerned with superconducting materials seek a broad understanding of the behavior of transition metal oxides, including high temperature superconductors. Researchers aim to extend the selection of such materials for possible electronic application and explore possible new device concepts. The group investigating structure and reactivity of oxide surfaces focuses on materials relevant for heterogeneous catalysis and environmental geochemistry. The magnetics group investigates materials problems related to the use of magnetic thin films in the data storage industry. Its initial goal is to understand the three related phenomena of giant magnetoresistance, magnetic anisotropy in thin films, and optical Kerr rotation in magnetic thin films. The center supports the development, operation and maintenance of shared experimental facilities for materials research. It provides seed funding for exploratory research and fosters research participation by undergraduates. This MRSEC is associated with an educational outreach program with emphasis on attracting and retaining women and underrepresented minorities in materials science and has initiated a summer science outreach program to predominantly minority high school students. The center administers an industrial outreach program. It currently supports about 20 faculty, 5 postdoctoral research associates, 4 technical staff member, 24 graduate students, and 10 undergraduates. This MRSEC is directed by Professor Malcolm R. Beasley.

The Materials Research Science and Engineering Center (MRSEC) known as the Center on Polymer Interfaces and Macromolecular Assemblies (CPIMA) at Stanford University is a partnership among research groups at Stanford University, IBM-Almaden, and the University of California Davis. The center supports interactive research through three interdisciplinary research groups. The group investigating macromolecular design for enhanced film properties aims to design and synthesize novel polymers which have unique optical and electronic properties, and then characterize their equilibrium and dynamical behavior when they are constrained by interfaces. Researchers in the group focused on ultrathin films aim to design and synthesize substrate-bound ultrathin organic films that mediate the chemical and physical interactions between the substrate and an adjacent overlayer. Investigators in the group investigating the dynamics of interfacial processing seek to understand the interfacial transport processes that occur during the fabrication of ultrathin films of polymers and polymer-based nanoncomposite materials. The center also supports the development, operation and maintenance of shared experimental facilities for materials research. It provides seed funding for exploratory research, and fosters research participation by undergraduates. The center has educational programs from high school to the graduate level and carries out collaborative research with industry. The center currently supports about 16 senior investigators, 12 postdoctoral research associates, 2 technical staff members, 18 graduate students, and 6 undergraduates. This MRSEC is directed by Professor Curtis W. Frank.

Principal Investigators
Nathalie de Leon (Electrical Engineering)
Stephen Lyon (Electrical Engineering)

* This seed is inactive.

This Seed 5 is working to develope materials engineering and surface processing tools to create and stabilize new color centers with diamonds for a variety of applications in quantum communication and nanoscale sensing.  

 

IRG3 exploits unique synthetic capabilities in high-pressure infiltration of semiconductors into diverse 3D nanotemplates to create new materials in which electronic, magnetic, and vibrational degrees of freedom interact with well-ordered nanometer-scale 3D structural modulations. Rigid nanotemplates will induce multi-GPA stresses onto semiconductors such as silicon that contract via crystallization within them, thereby tuning band gaps by nearly 2× while also varying other properties such as mobility and dopant solubility. Ordered, electrically continuous 3D structural modulations of extreme strain, quantum confinement, and interfacial physics will define a new physical regime for electronic, optical, magnetic, and thermal response, one that exploits diffraction effects to control thermal and electrical transport. The greatly altered palette of physical properties thereby made available in well-developed semiconductor platforms such as Si could enable practical application in diverse areas such as solar cells, near-IR photonics, light emitting devices, and improved thermoelectrics.

Mission:

This IRG focuses on the development of nitride- and ZnO-based semiconductor quantum structures, establishing inorganic semiconductor nanophotonic structures with large bandgap and high exciton binding energy for high-efficiency light emitters, lasers, energy conversion, and other quantum devices. The research scope includes the epitaxy and synthesis of GaN-and ZnO-based nanostructures, their structural, electrical and optical characterization, and their application in laser spectroscopy and quantum optical studies, investigation of strong coupling phenomena, polariton lasing, high-efficiency visible LEDs, and microcavity lasers.

Research Overview:

Modern photonic devices typically are based on the ubiquitous III-V semiconductor quantum structures, which constitute an archetypical example of a nanoscale system that has made an enormous impact in both basic condensed matter physics and applications. Conventional semiconductors, however, suffer from several limitations: their band gaps typically lie in the near-infrared spectral region, the exciton binding energy is small (few meV), and it is difficult to integrate the nanoscale structure to the micron scale with the accuracy required for many applications.  (For example, sufficiently accurate positioning of a single QD of precise size and composition within a photonic crystal or microcavity is extraordinarily challenging.) Hence, many quantum phenomena of interest are manifested only at very low temperatures, and the excitonic state is not stable at high density.

Recent breakthrough results by C-PHOM researchers have the prospect of enabling fundamental advances over such conventional approaches. For example, Bhattacharya’s group has recently demonstrated the growth of wide bandgap nitride quantum structures that operate with unprecedented efficiency in the visible spectrum. This work opens up a new frontier in wide bandgap semiconductor nanostructures for high-efficiency light emission, energy conversion, lasers, and applications to quantum information science.

The overall objectives of this IRG are to investigate the epitaxial growth of GaN- and ZnO-based nanowires and quantum confined heterostructures and exploit these unique materials to study light-matter coupling processes and investigate the intrinsic properties of efficient wide-gap quantum emitters. We characterize defects, strain, polarization fields and optical properties of the nanostructures. Laser spectroscopy and quantum optical studies include the characterization of single photon properties, relaxation and decoherence rates, dynamics of hot carriers, and quantum and spin coherence phenomena. Strong coupling phenomena and polariton emission properties areinvestigated at high temperatures. It is important to add that while there is ongoing work on the growth of nanowires and quantum structures, their intrinsic properties are yet to be elucidated; similarly very little work has been reported on the use of wide-bandgap GaN and ZnO-based heterostructures for the studies listed above. The characteristics of light-emitting diodes and lasers made with quantum dot and nanowire gain regions are being investigated.  For example, the role of Auger recombination, defects and carrier leakage in the performance of light-emitting diodes, which lead to efficiency roll-off, or “droop” is being examined theoretically and experimentally. This is a serious shortcoming in nitride-based LEDs, which impacts the progress of solid-state lighting.

Principal Investigator
Sanfeng Wu, Assistant Professor of Physics

Seed start and end dates: November 1, 2018 - October 31, 2019

One of the remarkable contributions of graphene research over the past decade is to teach us how to realize high quality 2D electronic systems in the simplest settings – materials with only a single atomic layer. In such atomic monolayers, the quantum electronic properties can be unprecedently controlled through external fields or van der Waals interface engineering. For instance, stacking two monolayer crystals in a twisted fashion can result in long wavelength Moiré patterns (Fig. 1A-C), which can significantly alter the electronic bands at low energies. At certain “magic” twist angles, the band can even be tuned to be very flat. In the case of graphene, this “twistronics” approach creates a flat band at an angle near 1.1o, leading to the observation of superconductivity. In general, it has pointed to a new, fascinating route to achieve flat bands and strong electron correlations without introducing any disorder, through controlling the stacking parameters of a van der Waals heterostructure.

An electronic flat band not only holds the promise to achieve high-Tc superconductivity, but also could lead to the observation of fractionalized quantum states at zero magnetic field. The latter requires the development of a flat band with strong spin-orbit coupling and non-trivial topology. However, graphene itself has very weak spin-orbit coupling, and its electronic band is topologically trivial at finite temperatures. Hence, it is of great interest to apply the twistronics approach to other 2D crystals, especially those with non-trivial topology.

Precise synthetic control of the local electronic structure of metal centers within materials offers the potential to engender exotic physical properties. In particular, tuning the electronic structure of metal centers enables the creation of strongly correlated electron systems, enabling researchers to ask fundamental questions about magnetism and superconductivity. Within this Seed, a team of researchers is working on harnessing classes of mixed anion systems to discover and manipulate magnetic and superconducting properties of materials. Currently, numerous materials offer the potential to host topologically interesting phenomena, thereby tying into the NSF goal of creating new quantum materials. Indeed, any material that offers fundamental excitations that differ from previously studied particles is of interest within this area.