Dmitry Ruzmetov

DEVCOM Army Research Laboratory

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Tony Ivanov

DEVCOM Army Research Laboratory

A. Glen Birdwell

DEVCOM Army Research Laboratory

A. Alec Talin

Sandia National Laboratories California

Pankaj B. Shah

DEVCOM Army Research Laboratory

Shriram Ramanathan

Rutgers, The State University of New Jersey

Mahesh R. Neupane

United States Army Combat Capabilities Development Command

Robert A. Burke

DEVCOM Army Research Laboratory

Mahesh R. Neupane

DEVCOM Army Research Laboratory

V. Narayanamurti

Harvard University

Paul M. Haney

Physical Measurement Laboratory

Cooperative Institutions

DEVCOM Army Research Laboratory

University of Maryland, College Park

National Institute of Standards and Technology

Rice University

United States Army Combat Capabilities Development Command

Pennsylvania State University

Material Measurement Laboratory

University of Virginia

National Institute of Standards

Oak Ridge National Laboratory

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Diamond Field-Effect Transistors With V₂O₅-Induced Transfer Doping: Scaling to 50-nm Gate Length

IEEE Transactions on Electron Devices (2020)

Kevin G. Crawford James Weil Pankaj B. Shah Dmitry Ruzmetov Mahesh R. Neupane

We report on the fabrication and measurement of hydrogen-terminated diamond field-effect transistors (FETs) incorporating V ₂ O ₅ as a surface acceptor material to induce transfer doping. Comparing a range of gate lengths down to 50 nm, we observe inversely scaling peak output current and transconductance. Devices exhibited a peak drain current of ~700 mA/mm and a peak transconductance of ~150 mS/mm, some of the highest reported thus far for a diamond metal semiconductor FET (MESFET). Reduced sheet resistance of the diamond surface after V ₂ O ₅ deposition was verified by four probe measurement. These results show great potential for improvement of diamond FET devices through scaling of critical dimensions and adoption of robust transition metal oxides such as V ₂ O ₅ .

Transconductance

MESFET

10.1109/ted.2020.2989736

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Citations (26)

New insights from in-situ electron microscopy into capacity loss mechanisms in all-solid-state Li-ion batteries with Al anodes.

Journal of Materials Chemistry (2014)

A. Alec Talin Marina Leite Dmitry Ruzmetov Zhipeng Li Leonid A. Bendersky

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Temperature Dependence of the Hall Effect in ferromagnetic Ga(1-x)Mn(x)As

APS (2002)

Dmitry Ruzmetov David V. Baxter Julia Scherschligt T. Wójtowicz Yuji C. Sasaki

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First-principles investigation of oxidized Si- and Ge-terminated diamond (100) surfaces

The Journal of Chemical Physics (2024)

Hector Gomez James Cruz Cody L. Milne Topojit Debnath A. Glen Birdwell

Diamond is a semiconductor material with remarkable structural, thermal, and electronic properties that has garnered significant interest in the field of electronics. Although hydrogen (H) and oxygen (O) terminations are conventionally favored in transistor designs, alternative options, such as silicon (Si) and germanium (Ge), are being explored because of their resilience to harsh processing conditions during fabrication. Density-functional theory was used to examine the non-oxidized and oxidized group-IV (Si and Ge)-terminated diamond (100) surfaces. The (3 × 1) reconstructed surfaces feature an ether configuration and show relative stability compared with the bare surface. Hybrid-functional calculations of the electronic properties revealed reduced fundamental bandgaps (<1 eV) and lower negative electron affinities (NEAs) than those of H-terminated diamond surfaces, which is attributed to the introduction of unoccupied Si (Ge) states and the depletion of negative charges. Furthermore, oxidation of these surfaces enhanced the stability of the diamond surfaces but resulted in two structural configurations: ether and ketone. Oxidized ether configurations displayed insulating properties with energy gaps of ∼4.3 ± 0.3 eV, similar to H-terminated diamond (100) surfaces, whereas bridged ether configurations exhibited metallic properties. Oxidization of the metallic ketone configurations leads to the opening of relatively smaller gaps in the range of 1.1–1.7 eV. Overall, oxidation induced a shift from NEAs to positive electron affinities, except for the reverse-ordered ketone surface with an NEA of −0.94 eV, a value comparable to the H-terminated diamond (100) surfaces. In conclusion, oxidized group-IV-terminated diamond surfaces offer enhanced stability compared to H-terminated surfaces and display unique structural and electronic properties that are influenced by surface bonding.

10.1063/5.0203185

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Structural and electronic properties of 2D (graphene, hBN)/H-terminated diamond (100) heterostructures

Applied Physics Letters (2020)

Pegah S. Mirabedini Bishwajit Debnath Mahesh R. Neupane P. Alex Greaney A. Glen Birdwell

We report a first-principles study of the structural and electronic properties of two-dimensional (2D) layer/hydrogen-terminated diamond (100) heterostructures. Both the 2D layers exhibit weak van-der-Waals (vdW) interactions and develop rippled configurations with the H-diamond (100) substrate to compensate for the induced strain. The adhesion energy of the hexagonal boron nitride (hBN) layer is slightly higher, and it exhibits a higher degree of rippling compared to the graphene layer. A charge transfer analysis reveals a small amount of charge transfer from the H-diamond (100) surface to the 2D layers, and most of the transferred charge was found to be confined within the vdW gap. In the graphene/H-diamond (100) heterostructure, the semi-metallic characteristic of the graphene layer is preserved. On the other hand, the hBN/H-diamond (100) heterostructure shows semiconducting characteristics with an indirect bandgap of 3.55 eV, where the hBN layer forms a Type-II band alignment with the H-diamond (100) surface. The resultant conduction band offset and valence band offset are 0.10 eV and 1.38 eV, respectively. A thin layer of hBN offers a defect-free interface with the H-diamond (100) surface and provides a layer-dependent tunability of electronic properties and band alignment for surface-doped diamond field effect transistors.

Band offset

10.1063/5.0020620

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Refractory metals as alternate contact metals for 2D/3D Heterostructures

Bulletin of the American Physical Society (2019)

Mahesh R. Neupane Dmitry Ruzmetov Robert A. Burke Matthew L. Chin Mike Valentin

Refractory metals

Refractory (planetary science)

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Metastable oxygen incorporation into thin film NiO by low temperature active oxidation: Influence on hole conduction

Journal of Applied Physics (2010)

Gulgun H. Aydogdu Dmitry Ruzmetov Shriram Ramanathan

The ability to controllably tune cation valence state and resulting electrical conductivity of transition metal-oxides such as NiO is of great interest for a range of solid state electronic and energy devices and more recently in understanding electron correlation phenomena at complex oxide interfaces. Here, we demonstrate that it is possible to enhance electrical conductivity of NiO thin films by one order of magnitude by photoexcitation and three orders of magnitude by ozone treatment at as low as 310 K. The change occurs within nearly 2000 s and, thereafter, reaches a self-limiting value. A surprising difference is seen at 400 K: ultraviolet photon and ozone treatments cause only a marginal reduction in resistance in the first few minutes and, then, the resistance begins to increase and recovers its original value. This unusual reversal is explained by considering metastable incorporation of oxygen in NiO and oxygen equilibration with the environment. Variation in nickel valence state prior to and after photoexcitation and ozone treatment, investigated by x-ray photoelectron spectroscopy, provides mechanistic insights into resistance trends. This study demonstrates photon-assisted and ozone oxidation as effective low temperature routes to tune the electrical properties as well as metastably incorporate oxygen into oxides with direct influence on electrical conduction properties.

Photoexcitation

Non-blocking I/O

Metastability

10.1063/1.3516473

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Infrared reflectance and photoemission spectroscopy studies across the phase transition boundary in thin film vanadium dioxide

Journal of Physics Condensed Matter (2008)

Dmitry Ruzmetov Kevin T. Zawilski Sanjaya D. Senanayake V. Narayanamurti Shriram Ramanathan

Optical properties and valence band density of states near the Fermi level of high-quality VO(2) thin films have been investigated by mid-infrared reflectometry and hard-UV (hν = 150 eV) photoemission spectroscopy. An exceptionally large change in reflectance from 2 to 94% is found upon the thermally driven metal-insulator transition (MIT). The infrared dispersion spectra of the reflectance across the MIT are presented and evidence for the percolative nature of the MIT is pointed out. The discrepancy between the MIT temperatures defined from the electrical and optical properties is found and its origin is discussed. The manifestation of the MIT is observed in the photoemission spectra of the V 3d levels. The analysis of the changes of the V 3d density of states is done and the top valence band shift upon the MIT is measured to be 0.6 eV.

Density of states

Inverse photoemission spectroscopy

Metal–insulator transition

10.1088/0953-8984/20/46/465204

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Fabrication, Testing, and Simulation of All-Solid-State Three-Dimensional Li-Ion Batteries

ACS Applied Materials & Interfaces (2016)

A. Alec Talin Dmitry Ruzmetov Andrei Kolmakov Kim McKelvey Nicholas Ware

Demonstration of three-dimensional all-solid-state Li-ion batteries (3D SSLIBs) has been a long-standing goal for numerous researchers in the battery community interested in developing high power and high areal energy density storage solutions for a variety of applications. Ideally, the 3D geometry maximizes the volume of active material per unit area, while keeping its thickness small to allow for fast Li diffusion. In this paper, we describe experimental testing and simulation of 3D SSLIBs fabricated using materials and thin-film deposition methods compatible with semiconductor device processing. These 3D SSLIBs consist of Si microcolumns onto which the battery layers are sequentially deposited using physical vapor deposition. The power performance of the 3D SSLIBs lags significantly behind that of similarly prepared planar SSLIBs. Analysis of the experimental results using finite element modeling indicates that the origin of the poor power performance is the structural inhomogeneity of the 3D SSLIB, coupled with low electrolyte ionic conductivity and diffusion rate in the cathode, which lead to highly nonuniform internal current density distribution and poor cathode utilization.

Power density

Deposition

10.1021/acsami.6b12244

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Citations (113)

Local electrical characterization of cadmium telluride solar cells using low-energy electron beam

Solar Energy Materials and Solar Cells (2013)

Heayoung P. Yoon Paul M. Haney Dmitry Ruzmetov Hua Xu Marina S. Leite

Electron beam-induced current

Cadmium telluride photovoltaics

Band bending

10.1016/j.solmat.2013.07.024

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Citations (41)