YIP: Phase-Change Correlated Perovskites as a New Platform for Photonics

Phase-Change Correlated Perovskites as a New Platform for PhotonicsProf. Nanfang Yu, Columbia (Code 03R-funded YIP), 15 March 2016Objective:The objectives of this program are to understand the optical properties of correlated nickelates that undergo electronic phase change, and to investigate the potential of using such phase-change materials for active photonic device applications.Approach:One of the phase-change materials that will be the focus of our investigation is samarium nickelate, SmNiO3. It has recently been demonstrated that SmNiO3 can be electrically switched between its two phases (i.e., transparent correlated dielectric and opaque narrow-band semiconductor) by electron doping at room temperature. The two phases differ in their electrical resistivity by eight orders of magnitude and optical band gap by an order of magnitude at room temperature.We propose to demonstrate large modulation of light with high speed by using a hybrid structure consisting of a two-dimensional (2D) array of optical antennas (i.e., ~metasurfaces~) integrated with phase-change correlated nickelates, which provide tunable optical refractive indices. We will also investigate the hybrid structure as a platform for nonvolatile optical memory, where information can be stored as a spatial distribution of tunable optical refractive indices of the phase-change materials. The challenge of realizing both optical modulation and optical memory is to maximize the effect of phase change on optical signals (i.e., modulated optical signal/readout signal of the optical memory), while simultaneously minimizing the amount of phase-change materials used in order to achieve high-speed performance (i.e., high-speed optical modulation/programming of optical memory). The challenge necessitates the use of metasurfaces, as they mediate strong light-matter interactions on a 2D plane (i.e., co-location of intensely confined light and thin films of phase-change materials).Strong electron correlation in SmNiO3 as a result of electron doping drastically opens up the optical band gap (from ~200 meV to ~3 eV), which leads to substantially changes of the optical refractive indices from the visible to the long-wavelength mid-infrared (~=400nm-20~m). We propose to explore the super broadband performance of SmNiO3 to create smart windows that provide complete control of sunlight and variable emissivity coatings that can be used for adaptive infrared camouflage and radiative thermal control.SOW:Year 1. Study the nature and dynamics of phase change in correlated perovskite nickelatesStudy electronic transport in electron-doped SmNiO3 films that have been synthesized by hydrogenation or lithium intercalation at various temperaturesStudy the stability and dynamics of phase change: non-volatility of the electron doping process and fundamental limit on the number of phase-change cycles before material failureInvestigate the fundamental limit on the speed of phase change in perovskite nickelates Systematic study of other phase-change perovskite nickelates (e.g., NdNiO3)Year 2. Investigate fabrication techniques to integrate phase-change perovskite nickelates and metasurface structuresSynthesize ultra-thin perovskite nickelates on metallic surfaces and on suspended Si3N4 membranes; reduce surface roughness of synthesized thin filmsInvestigate lithographic and physical/chemical etching techniques to pattern dielectric/metallic metasurface structures on thin films of phase-change perovskite nickelatesInvestigate lithographic and etching techniques to directly pattern phase-change perovskite nickelates into nano/micro-structuresYear 3. Demonstrate active photonic devices based on phase-change perovskite nickelatesDemonstrate high-speed solid-state optical modulators by integrating phase-change perovskite nickelates and metasurface structuresDemonstrate electrically programmable non-volatile optical memory devicesDemonstrate smart windows for dynamic and complete control of sunlight in t