About

Prabhakar Bandaru leads a research group focused on the electronic, electrochemical, and thermal properties of materials. The group investigates a variety of topics including electrokinetics of superhydrophobic surfaces, quantum tunneling for enhanced photoemission, modeling of electrokinetic flows over structured surfaces, synthesis and characterization of electroactive polymers, thermal metamaterials, electrochemical analysis of biomolecular kinetics in field-effect transistor sensors, and topological physics related to ferroelectrics and low dimensional materials and devices. The group also studies corrosion phenomena relevant to fuel cells. Weekly group meetings and journal clubs foster collaborative problem solving and discussion of frontier research topics. The research spans experimental, theoretical, and computational approaches to understanding and manipulating material properties at the nanoscale, with applications in sensors, energy devices, and advanced materials engineering.

Research topics

• Materials science
• Engineering physics
• Thermodynamics
• Physics
• Engineering
• Composite material
• Mechanics
• Mechanical engineering
• Optoelectronics
• Electrical engineering
• Biology
• Chemistry
• Biochemistry
• Biophysics
• Computational biology
• Molecular biology

Selected publications

• Helical Phononic Modes Induced by a Screw Dislocation

  Advanced Functional Materials · 2025-04-01 · 3 citations

  articleOpen accessCorresponding

  Abstract A 1D unidirectional phononic waveguide embedded within a 3D hexagonal close‐packed (HCP) phononic crystal is investigated, formed through the introduction of a screw dislocation. This approach does not rely on the non‐trivial topological characteristics of the 3D crystal. The findings reveal that the screw dislocation induces a pair of helical modes with orthogonal displacements in the x ‐ and y ‐directions, which are 90 degrees out of phase, resulting in distinctive rotational motion. These helical modes exhibit directional propagation, tightly linked to the helicity of the screw dislocation. The observed directionality and robustness are attributed to the interplay between the structural helicity and the existence of a bulk bandgap. This work provides new insights into the influence of dislocation‐induced symmetry on wave propagation in phononic systems. It also offers a pathway for designing directionally selective waveguides without relying on topological properties.

  PublisherOA PDFDOI

• Low-voltage polarization switching in ferroelectric FinFET-based memory devices, using electric field nonlinearities

  Journal of Computational Electronics · 2025-05-31

  articleSenior author
  PublisherDOI

• Low-Voltage Graphene Interface-Engineered Organic Ferroelectric Tunnel Junction Devices

  ACS Applied Materials & Interfaces · 2025-05-26 · 1 citations

  preprintOpen accessSenior authorCorresponding

  It has been indicated that the path forward for the widespread usage of ferroelectric (FE) materials may be considerably facilitated through the reduction of programming voltages to on-chip logic-compatible values of <1 V. Obstacles involve issues related to the scaling of the FEs to lower thickness as well as the presence of an interfacial layer (IL) between the high-permittivity FE and the substrate- resulting in wasted voltage across the IL. Here, we show how lower operating voltages along with a higher tunneling electroresistance (TER) could be achieved through IL engineering. We use piezoresponse force microscopy and fabricated ferroelectric tunnel junctions (FTJs) to show that ultrathin FE films deposited on single-layer graphene/Si can exhibit polarization switching at reduced voltages ∼0.8 V with significant TER as compared to directly depositing on Si.

  PublisherOA PDFDOI

• Corrosion Behavior of Additively Manufactured AlCoCrFeNi _2.1 Eutectic High Entropy Alloys as a Function of Annealing Conditions

  ECS Meeting Abstracts · 2025-11-24

  article

  Eutectic high-entropy alloys (EHEAs), such as nano-lamellar AlCoCrFeNi₂.₁, have gained widespread attention due to their excellent mechanical properties, high hardness, wear resistance, and corrosion resistance—even at elevated temperatures (e.g., &gt;1000 °C). In this study, we investigated the corrosion behavior of AlCoCrFeNi₂.₁ EHEAs fabricated via laser powder bed fusion (L-PBF) 3D printing, as a function of annealing temperature. These EHEAs are composed of two phases: a ductile FCC L1₂ phase and a high-strength BCC B2 phase. Due to the rapid solidification inherent to L-PBF, the as-printed microstructure is far from equilibrium, resulting in a nearly homogeneous elemental distribution across phases. Upon annealing, the system evolves toward equilibrium, leading to enrichment of Cr, Co, and Fe in the FCC phase and Al and Ni in the BCC phase. Additionally, because Cr has limited solubility in the B2 phase, Cr-rich precipitates (on the order of tens of nanometers) form and become more prominent with higher annealing temperatures. Three processing conditions were considered in this study: (1) as printed, (2) annealed at 600 °C for 5 hours, and (3) annealed at 1000 °C for 1 hour. With increasing annealing temperature, the lamellar B2 phase coarsened, Cr-rich precipitates grew, and elemental segregation became more pronounced. Samples were characterized using electron backscatter diffraction to determine crystallographic orientation and energy-dispersive spectroscopy to assess local composition. Further, in situ electrochemical Atomic Force Microscopy was deployed to investigate the relationship between microstructure and corrosion behavior. These studies revealed preferential corrosion of the B2 phase and was most pronounced in regions adjacent to Cr-rich precipitates, where the matrix is depleted in Cr. Corrosion was found to be greater in samples subject to increased annealing temperature. For instance, after 5 hours exposure in 0.05 M H 2 SO 4 , corrosion pit depths increased from ~ 10 nm in the as-printed structure to ~360 nm on the sample annealed at 1000°C, while the pitted area increased from ~2% to 12%. Additionally, electrochemical impedance spectroscopy was used to quantify the charge transfer resistance-an indicator inversely proportional to the corrosion rate- and to monitor oxide evolution. Laser confocal microscopy was used to assess corrosion over larger areas and extended time scales. We expect that such a multimodal approach will inform processing methodologies to design materials systems for high mechanical performance and robust corrosion resistance. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  PublisherDOI

• Packing fraction related transport in disordered quantum dot arrays

  Applied Physics Letters · 2025-03-01 · 1 citations

  articleSenior author

  Models to describe electrical conduction in quantum dot (QD) constituted films often overlook the effects of geometric disorder. We address related issues by examining the influence of the QD packing fraction (PF) on the charge transport and transmission in QD arrays. Using transfer matrix based algorithms and Monte Carlo simulations, we quantify the transmission across disordered QD assemblies. Our results indicate a critical packing fraction (PFc) of ∼ 0.64, marking a transition from a non-conducting to a conducting state, aligning well with experimental observations and analytical predictions. This study enhances the understanding of transport in QD arrays, with implications for designing efficient electronic devices based on disordered nanoscale systems.

  PublisherDOI

• Long-range order of polygonal grain boundaries

  Physical review. B./Physical review. B · 2025-01-02

  article

  Atomic-scale spatial resolution was achieved in the mapping and spectroscopy of polygonal grain boundaries (GBs) on atomically flat highly oriented pyrolytic graphite using scanning tunneling microscopy (STM). These GBs are long-range ordered one-dimensional periodic structures comprising pentagon-heptagon pairs. A comprehensive study combining local electronic, valleytronic, mechanical, and topological properties is conducted on this GB which reveals the interplay between these properties. On the atoms and bonds of individual GB polygons, spatially localized conductance states were probed, in addition to edge states. The spatial extent of these states was observed on GB by bias-dependent imaging. The electron scattering angle at the GB edges was also modulated with a sample bias which exhibited valley flipping and unique quantum interference effects such as backscattering and intervalley scattering. In situ strain-induced mechanical and electronic modifications were observed through surface deformation caused by the STM tip, revealing flattened electronic energy band dispersion and shifts in carrier doping.

  PublisherDOI

• Atomic Layer Deposition of TiO_<i>x</i>/Al₂O₃ Nanofilms on Aluminum Screens for Enhanced Corrosion Resistance in Electrolyzers

  ACS Applied Nano Materials · 2025-08-05

  articleSenior authorCorresponding

  This study presents a multistep approach to enhance the corrosion resistance of aluminum (Al) screens used in the flow fields of water electrolyzers, allowing for the higher thermal conductivity material, Al, to replace titanium (Ti) in electrolyzer gas diffusion components. The approach involves electropolishing, O2 treatment, and nanoscale conformal atomic layer deposition of an Al2O3 adhesion layer followed by a bilayer TiOx protection coating on the Al screens. It is shown that optimized coatings reduce corrosion current density by 4 orders of magnitude compared to uncoated Al, with a corrosion rate of ∼7 nm per year, ensuring protection of components with the complex geometries of the electrolyzer gas diffusion layer flow field. This work provides a viable pathway to replace expensive titanium with abundant, cost-effective aluminum.

  PublisherDOI

• High speed, high thermal-conductivity of aluminum nitride deposited by DC reactive sputtering at low temperature in the transition regime

  Ceramics International · 2025-12-17

  article
  PublisherDOI

• Improved corrosion resistance and electrical characteristics of titanium, with atomic layer deposited (ALD) TiOx coating

  Applied Surface Science · 2025-02-18 · 10 citations

  articleOpen accessSenior authorCorresponding

  • Voltage reduced for Ti anodization at elevated temperature. • ALD TiO x forms an effective oxygen diffusion barrier layer hence to prevent further oxidation of titanium. • ALD TiO x coating reduces corrosion of titanium in PEM electrolyzers at low pH. • Five orders of magnitude increase in current density with ALD TiO x -coated titanium. Titanium (Ti), widely used in proton exchange membrane (PEM) based water electrolyzers, is prone to oxidation and related corrosion given the high operating voltages (>2 V) and low pH (⩽5) conditions. Here, it is shown that a thin layer of ALD (atomic layer deposition) TiO x can serve as a barrier for drastically reducing the corrosion of Ti. The robustness of the coatings was evaluated at high potentials (2.4 V vs. RHE – reversible hydrogen electrode), in low pH and at elevated temperature (80 °C). A low TiO x dissolution rate (<∼5 nm year −1 ) along with five orders of magnitude enhanced current density, was observed for the ALD TiO x coated Ti compared to uncoated Ti.

  PublisherDOI

• Spatio-chemical characterization and elimination of localized growth aberrations on monolayer MoS2 for enhanced performance top gated FETs with scaled ALD oxides

  Applied Surface Science · 2025-10-18

  articleOpen accessSenior authorCorresponding

  • IR-PiFM maps identify growth artefacts on CVD grown monolayer MoS 2 as MoO x particles. • Sacrificial Al 2 O 3 layer cleaning process removes MoS 2 surface contaminants effectively. • Thin conformal ALD seed layer (∼1.3 nm) used for high-k gate oxide on monolayer MoS 2. • Cleaned MoS 2 FETs show 10–100 × higher on-current, lower SS and lower variability. • Process is CMOS-compatible and scalable for wafer-level applications. Obstacles towards the widespread use of two-dimensional materials, including MoS 2 , are high-quality large-scale growth of low defect density monolayers. A novel surface cleaning procedure, applicable in device technology, has been developed based on the use of an ALD sacrificial layer to eliminate growth aberrations. The imperfections on MoS 2 were identified using infrared photo-induced force microscopy (IR-PiFM) as MoO x particles deposited during CVD growth process. The utility of the procedure was tested through the fabrication of top gated field effect transistors (FETs) using a bilayer stack of low temperature ALD Al 2 O 3 (LT Al 2 O 3 ) seed layer followed by HfO 2 as the gate oxide. It was observed that the cleaning process results in 1–2 orders of magnitude improvement in the on-current, with a ∼30 % reduction in subthreshold swing, along with lower device variability.

  PublisherDOI

Recent grants

• Heat transfer processes in patterned and rough microchannels

  NSF · $306k · 2016–2022

• NER: Nano-Electronic Components Based on Carbon Nanotube Y-Junctions

  NSF · $100k · 2005–2006

• CAREER: Nonlinear Carbon Nanotube and Nanowire Morphologies for Unique Nanoelectronics

  NSF · $436k · 2007–2013

Frequent coauthors

• Sung Hoon Park

  The University of Texas at Austin

  22 shared

• Rajaram Narayanan

  20 shared

• Hidenori Yamada

  Tsurumi University

  18 shared

• Zichen Zhang

  17 shared

• Apparao M. Rao

  Clemson University

  15 shared

• Krishna P. Vemuri

  University of California, San Diego

  14 shared

• Andrew C. Kummel

  University of California, San Diego

  13 shared

• Bei Fan

  Michigan State University

  13 shared

Labs

• Bandaru groupPI

  Electronic, Electrochemical, and Thermal Properties of Materials

Education

• Ph.D., Materials Science

  UC, Berkeley

  1998

• B.S.

  Not specified

Awards & honors

• Vice Chancellor's award for graduate dissertation research a…