P. M. Thibado
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View article: Array of mini-graphene-silicon solar cells intermittently recharges storage capacitors powering a temperature sensor
Array of mini-graphene-silicon solar cells intermittently recharges storage capacitors powering a temperature sensor Open
Developing autonomous sensor systems that draw power from the ambient environment is a critical step for creating the Internet of Things. In this study, the authors built dozens of graphene-based solar cells, wire bonded them into standard…
View article: Spectrum Analysis of Thermally Driven Curvature Inversion in Strained Graphene Ripples for Energy Conversion Applications via Molecular Dynamics
Spectrum Analysis of Thermally Driven Curvature Inversion in Strained Graphene Ripples for Energy Conversion Applications via Molecular Dynamics Open
The extraordinary mechanical flexibility, high electrical conductivity, and nanoscale instability of freestanding graphene make it an excellent candidate for vibration energy harvesting. When freestanding graphene is stretched taut and sub…
View article: Transient Thermal Energy Harvesting at a Single Temperature Using Nonlinearity
Transient Thermal Energy Harvesting at a Single Temperature Using Nonlinearity Open
The authors present an in-depth theoretical study of two nonlinear circuits capable of transient thermal energy harvesting at one temperature. The first circuit has a storage capacitor and diode connected in series. The second circuit has …
View article: Low-Level Kinetic-Energy-Powered Temperature Sensing System
Low-Level Kinetic-Energy-Powered Temperature Sensing System Open
Powering modern nanowatt sensors from omnipresent low-level kinetic energy: This study investigates the power levels produced by a varying-capacitance kinetic energy harvesting system. A model system consisting of a uniformly driven rotati…
View article: Array of Graphene Solar Cells on 100 mm Silicon Wafers for Power Systems
Array of Graphene Solar Cells on 100 mm Silicon Wafers for Power Systems Open
High electrical conductivity and optical transparency make graphene a suitable candidate for photovoltaic-based power systems. In this study, we present the design and fabrication of an array of graphene-based Schottky junction solar cells…
View article: Charging capacitors from thermal fluctuations using diodes
Charging capacitors from thermal fluctuations using diodes Open
We theoretically consider a graphene ripple as a Brownian particle coupled to an energy storage circuit. When circuit and particle are at the same temperature, the second law forbids harvesting energy from the thermal motion of the Brownia…
View article: Freestanding graphene heat engine analyzed using stochastic thermodynamics
Freestanding graphene heat engine analyzed using stochastic thermodynamics Open
We present an Ito-Langevin model for freestanding graphene connected to an electrical circuit. The graphene is treated as a Brownian particle in a double-well potential and is adjacent to a fixed electrode to form a variable capacitor. The…
View article: Array of Graphene Variable Capacitors on 100 mm Silicon Wafers for Vibration-Based Applications
Array of Graphene Variable Capacitors on 100 mm Silicon Wafers for Vibration-Based Applications Open
Highly flexible, electrically conductive freestanding graphene membranes hold great promise for vibration-based applications. This study focuses on their integration into mainstream semiconductor manufacturing methods. We designed a two-ma…
View article: Mechanisms of Spontaneous Curvature Inversion in Compressed Graphene Ripples for Energy Harvesting Applications via Molecular Dynamics Simulations
Mechanisms of Spontaneous Curvature Inversion in Compressed Graphene Ripples for Energy Harvesting Applications via Molecular Dynamics Simulations Open
Electrically conductive, highly flexible graphene membranes hold great promise for harvesting energy from ambient vibrations. For this study, we built numerous three-dimensional graphene ripples, with each featuring a different amount of c…
View article: Fluctuation-induced current from freestanding graphene
Fluctuation-induced current from freestanding graphene Open
At room temperature, micron-sized sheets of freestanding graphene are in constant motion, even in the presence of an applied bias voltage. We quantify the out-of-plane movement by collecting the displacement current using a nearby small-ar…
View article: Efficient circuit design for low power energy harvesting
Efficient circuit design for low power energy harvesting Open
We present five circuit topologies for low power energy harvesting. The most efficient circuit uses a variable capacitor as the power source, a DC bias voltage to charge the variable capacitor, two transistors for rectification, and two st…
View article: Origin of Non‐Gaussian Velocity Distribution Found in Freestanding Graphene Membranes
Origin of Non‐Gaussian Velocity Distribution Found in Freestanding Graphene Membranes Open
In this study, an analytic derivation is made for the truncated Cauchy‐Lorentz velocity distribution experimentally observed in freestanding graphene membranes. Three methods are used and discussed, including the Fokker‐Planck‐Kolmogorov e…
View article: Anomalous Dynamical Behavior of Freestanding Graphene Membranes
Anomalous Dynamical Behavior of Freestanding Graphene Membranes Open
We report subnanometer, high-bandwidth measurements of the out-of-plane (vertical) motion of atoms in freestanding graphene using scanning tunneling microscopy. By tracking the vertical position over a long time period, a 1000-fold increas…
View article: Reflection high-energy electron diffraction and scanning tunneling microscopy study of InP(001) surface reconstructions
Reflection high-energy electron diffraction and scanning tunneling microscopy study of InP(001) surface reconstructions Open
The reconstructions of the InP(001) surface prepared by molecular beam epitaxy have been studied with in situ reflection high-energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). The growth chamber contains a highly…
View article: Controlling Mn Depth Profiles in GaMnAs During High-Temperature Molecular Beam Epitaxial Growth
Controlling Mn Depth Profiles in GaMnAs During High-Temperature Molecular Beam Epitaxial Growth Open
Mn-doped GaAs thin films were grown at a high substrate temperature of 580 C. During the growth process, the Mn cell temperature was ramped at different rates, resulting in a variety of different Mn concentration depth profile slopes, as m…
View article: Giant Surface Charge Density of Graphene Resolved From Scanning Tunneling Microscopy and First-Principles Theory
Giant Surface Charge Density of Graphene Resolved From Scanning Tunneling Microscopy and First-Principles Theory Open
In this work, systematic constant-bias, variable-current scanning tunneling microscopy (STM) measurements and STM simulations from density-functional theory are made, yielding critical insights into the spatial structure of electrons in gr…
View article: Atomic Control of Strain in Freestanding Graphene
Atomic Control of Strain in Freestanding Graphene Open
In this study, we describe a new experimental approach based on constant-current scanning tunneling spectroscopy to controllably and reversibly pull freestanding graphene membranes up to 35 nm from their equilibrium height. In addition, we…
View article: High-Percentage Success Method for Preparing and Pre-Evaluating Tungsten Tips for Atomic-Resolution Scanning Tunneling Microscopy
High-Percentage Success Method for Preparing and Pre-Evaluating Tungsten Tips for Atomic-Resolution Scanning Tunneling Microscopy Open
A custom double-lamella method is presented for electrochemically etching tungsten wire for use as tips in scanning tunneling microscopy (STM). For comparison, tips were also manufactured in-house using numerous conventional methods and ex…
View article: A Pathway between Bernal and Rhombohedral Stacked Graphene Layers with Scanning Tunneling Microscopy
A Pathway between Bernal and Rhombohedral Stacked Graphene Layers with Scanning Tunneling Microscopy Open
Horizontal shifts in the top layer of highly oriented pyrolytic graphite, induced by a scanning tunneling microscope (STM) tip, are presented. Excellent agreement is found between STM images and those simulated using density functional the…
View article: Schottky barrier and attenuation length for hot hole injection in non-epitaxial Au on p-type GaAs
Schottky barrier and attenuation length for hot hole injection in non-epitaxial Au on p-type GaAs Open
Ballistic electron emission microscopy (BEEM) was performed to obtain nanoscale current versus bias characteristics of non-epitaxial Au on p-type GaAs in order to accurately measure the local Schottky barrier height. Hole injection BEEM da…
View article: New Scanning Tunneling Microscopy Technique Enables Systematic Study of the Unique Electronic Transition from Graphite to Graphene
New Scanning Tunneling Microscopy Technique Enables Systematic Study of the Unique Electronic Transition from Graphite to Graphene Open
A series of measurements using a novel technique called electrostatic-manipulation scanning tunneling microscopy were performed on a highly-oriented pyrolytic graphite (HOPG) surface. The electrostatic interaction between the STM tip and t…
View article: Atomic-Scale Movement Induced in Nano-Ridges by Scanning Tunneling Microscopy on Epitaxial Graphene Grown on 4H-SiC(0001)
Atomic-Scale Movement Induced in Nano-Ridges by Scanning Tunneling Microscopy on Epitaxial Graphene Grown on 4H-SiC(0001) Open
Nanoscale ridges in epitaxial multilayer graphene grown on the silicon face of 4 degree off-cut 4H-SiC (0001) were found using scanning tunneling microscopy (STM). These nano-ridges are only 0.1 nm high and 25-50 nm wide, making them much …
View article: Role of bias voltage and tunneling current in the perpendicular displacements of freestanding graphene via scanning tunneling microscopy
Role of bias voltage and tunneling current in the perpendicular displacements of freestanding graphene via scanning tunneling microscopy Open
Systematic displacement measurements of freestanding graphene as a function of applied bias voltage and tunneling current setpoint using scanning tunneling microscopy (STM) are presented. When the bias voltage is increased the graphene app…
View article: Etch-stop method for reliably fabricating sharp yet mechanically stable scanning tunneling microscope tips
Etch-stop method for reliably fabricating sharp yet mechanically stable scanning tunneling microscope tips Open
An extension of the direct-current, double-lamella drop-off technique for electrochemically etching tungsten scanning-tunneling-microscope tips is presented. The key fabrication step introduced here is the use of an etch stop as a simple b…
View article: Graphene ripples as a realization of a two-dimensional Ising model: A scanning tunneling microscope study
Graphene ripples as a realization of a two-dimensional Ising model: A scanning tunneling microscope study Open
Ripples in pristine freestanding graphene naturally orient themselves in an\narray that is alternately curved-up and curved-down; maintaining an average\nheight of zero. Using scanning tunneling microscopy (STM) to apply a local\nforce, th…