Author
Timothy A. Grotjohn
Other affiliations: University of Paris, Purdue University
Bio: Timothy A. Grotjohn is an academic researcher from Michigan State University. The author has contributed to research in topics: Diamond & Microwave. The author has an hindex of 29, co-authored 143 publications receiving 2622 citations. Previous affiliations of Timothy A. Grotjohn include University of Paris & Purdue University.
Papers published on a yearly basis
Papers
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Sandia National Laboratories1, University of California, Davis2, Massachusetts Institute of Technology3, Cornell University4, United States Army Research Laboratory5, Ohio State University6, University of California, Santa Barbara7, Boston University8, North Carolina State University9, Purdue University10, Georgia Institute of Technology11, Michigan State University12, Air Force Research Laboratory13, National Institute of Information and Communications Technology14, University of South Carolina15, United States Naval Research Laboratory16, Arizona State University17, University of Illinois at Urbana–Champaign18, Vanderbilt University19
TL;DR: The UWBG semiconductor materials, such as high Al‐content AlGaN, diamond and Ga2O3, advanced in maturity to the point where realizing some of their tantalizing advantages is a relatively near‐term possibility.
Abstract: J. Y. Tsao,* S. Chowdhury, M. A. Hollis,* D. Jena, N. M. Johnson, K. A. Jones, R. J. Kaplar,* S. Rajan, C. G. Van de Walle, E. Bellotti, C. L. Chua, R. Collazo, M. E. Coltrin, J. A. Cooper, K. R. Evans, S. Graham, T. A. Grotjohn, E. R. Heller, M. Higashiwaki, M. S. Islam, P. W. Juodawlkis, M. A. Khan, A. D. Koehler, J. H. Leach, U. K. Mishra, R. J. Nemanich, R. C. N. Pilawa-Podgurski, J. B. Shealy, Z. Sitar, M. J. Tadjer, A. F. Witulski, M. Wraback, and J. A. Simmons
785 citations
Patent•
26 Aug 2003TL;DR: In this paper, a MEMS chip sensor (10, 20, 30, 40, 50, 60, 70) based on detection of induced inductance in the sensor is described.
Abstract: A MEMS chip sensor (10, 20, 30, 40, 50, 60, 70) based upon detection of an induced inductance in the sensor is described. The sensor is used in an environment for detection of fluid pressures. The method and system is particularly used in animals, including humans, to sense pressure changes, particularly pressure in the eyeball.
156 citations
TL;DR: In this article, a self-consistent two-dimensional model of the electromagnetic field and the plasma in a hydrogen discharge system has been developed and tested in comparison to experimental measurements, which is a 25 cm diameter resonant cavity structure operating at 2.45 GHz with a silica belljar of 10 cm diameter and 17 cm height contained within the microwave cavity.
Abstract: A self-consistent two-dimensional model of the electromagnetic field and the plasma in a hydrogen discharge system has been developed and tested in comparison to experimental measurements. The reactor studied is a 25 cm diameter resonant cavity structure operating at 2.45 GHz with a silica belljar of 10 cm diameter and 17 cm height contained within the microwave cavity. The inside of the belljar where the discharge occurs contains a substrate holder of 5 cm diameter that is used to hold substrates for diamond deposition. The electromagnetic field model solves for the microwave fields using a finite difference time-domain solution of Maxwell’s equations. The plasma model is a three energy mode (gas, molecular vibration, and electron) and nine species (H2, H, H(n=2), H(n=3), H+, H2+, H3+, H−, electron) model which accounts for non-Boltzmann electron distribution function and has 35 reactions. Simulated characteristics of the reactor in two dimensions include gas temperature, electron temperature, electron density, atomic hydrogen molar fraction, microwave power absorption, and microwave fields. Comparisons of the model are made with close agreement to several experimental measurements including coherent anti-Stokes Raman Spectroscopy measurement of H2 temperature versus position above the substrate, Doppler broadening optical emission spectroscopy (OES) measurements of H temperature versus pressure, actinometry measurements of the relative H atom concentration, Hα OES intensity measurements versus position, and microwave electric field measurements. The parameter range studied includes pressures of 2500–11 000 Pa, microwave powers of 300–2000 W, and three vertical positions of the substrate holder.
147 citations
TL;DR: In this article, a parametric model with short-channel capabilities is presented for MOS transistors, which covers the subthreshold and strong inversion regions with a continuous transition between these regions.
Abstract: A parametric model with short-channel capabilities is presented for MOS transistors. It covers the subthreshold and strong inversion regions with a continuous transition between these regions. The effects included in the model are mobility reduction, carrier velocity saturation, body effect, source-drain resistance, drain-induced barrier lowering, and channel length modulation. The model simulates accurately the current characteristics as well as the transconductance and output conductance characteristics which are important for analog circuit simulation.
89 citations
TL;DR: GaN-on-diamond device cooling can be enhanced by reducing the effective thermal boundary resistance (TBReff) of the GaN/diamond interface and the thermal properties of the polycrystalline diamond grown onto GaN using SiN and AlN barrier layers as well as without any barrier layer under different growth conditions are investigated and systematically compared for the first time.
Abstract: GaN-on-diamond device cooling can be enhanced by reducing the effective thermal boundary resistance (TBReff) of the GaN/diamond interface. The thermal properties of this interface and of the polycrystalline diamond grown onto GaN using SiN and AlN barrier layers as well as without any barrier layer under different growth conditions are investigated and systematically compared for the first time. TBReff values are correlated with transmission electron microscopy analysis, showing that the lowest reported TBReff (∼6.5 m2 K/GW) is obtained by using ultrathin SiN barrier layers with a smooth interface formed, whereas the direct growth of diamond onto GaN results in one to two orders of magnitude higher TBReff due to the formation of a rough interface. AlN barrier layers can produce a TBReff as low as SiN barrier layers in some cases; however, their TBReff are rather dependent on growth conditions. We also observe a decreasing diamond thermal resistance with increasing growth temperature.
84 citations
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Journal Article•
28,685 citations
TL;DR: In this article, the authors present stretchable and printable semiconductors and electronic circuits capable of providing good performance when stretched, compressed, flexed, or otherwise deformed.
Abstract: The present invention provides stretchable, and optionally printable, semiconductors and electronic circuits capable of providing good performance when stretched, compressed, flexed or otherwise deformed. Stretchable semiconductors and electronic circuits of the present invention preferred for some applications are flexible, in addition to being stretchable, and thus are capable of significant elongation, flexing, bending or other deformation along one or more axes. Further, stretchable semiconductors and electronic circuits of the present invention may be adapted to a wide range of device configurations to provide fully flexible electronic and optoelectronic devices.
1,673 citations
01 Jan 1993
TL;DR: In this article, particle-in-cell (PIC) combined with Monte Carlo collision (MCC) calculations are used for simulation of partially ionized gases, with many of the features met in low-temperature collision plasmas.
Abstract: Many-particle charged-particle plasma simulations using spatial meshes for the electromagnetic field solutions, particle-in-cell (PIC) merged with Monte Carlo collision (MCC) calculations, are coming into wide use for application to partially ionized gases. The author emphasizes the development of PIC computer experiments since the 1950s starting with one-dimensional (1-D) charged-sheet models, the addition of the mesh, and fast direct Poisson equation solvers for 2-D and 3-D. Details are provided for adding the collisions between the charged particles and neutral atoms. The result is many-particle simulations with many of the features met in low-temperature collision plasmas; for example, with applications to plasma-assisted materials processing, but also related to warmer plasmas at the edges of magnetized fusion plasmas. >
1,022 citations
TL;DR: In this article, the development and application of magnetron sputtering systems for ionized physical vapor deposition (IPVD) is reviewed, and the application of a secondary discharge, inductively coupled plasma magnetron (ICP-MS), microwave amplified magnetron, and self-sustained sputtering (SSS) is discussed as well as the hollow cathode magnetron discharges.
972 citations
TL;DR: In this article, a new method for the extraction of the MOSFET parameters is presented, which relies on combining drain current and transconductance transfer characteristics, enabling reliable values of the threshold voltage V/sub t/, the low field mobility mu /sub 0/ and the mobility attenuation coefficient theta to be obtained.
Abstract: A new method for the extraction of the MOSFET parameters is presented. The method, which relies on combining drain current and transconductance transfer characteristics, enables reliable values of the threshold voltage V/sub t/, the low field mobility mu /sub 0/ and the mobility attenuation coefficient theta to be obtained.
761 citations