Papers by Akintunde Akinwande
Proceedings of the National Academy of Sciences, 2019
Significance We demonstrate that it is possible to use deep neural networks to produce tomographi... more Significance We demonstrate that it is possible to use deep neural networks to produce tomographic reconstructions of dense layered objects with small illumination angle as low as 10 °. It is also shown that a DNN trained on synthetic data can generalize well to and produce reconstructions from experimental measurements. This work has application in the field of X-ray tomography for the inspection of integrated circuits and other materials studies.
Twenty-First International Conference on Thermoelectrics, 2002. Proceedings ICT '02.
Nanowires made of thermoelectric-relevant materials were grown in the pores of alumina templates ... more Nanowires made of thermoelectric-relevant materials were grown in the pores of alumina templates fabricated on silicon wafers. This architecture combines the nanometer-scale, self-assembly nature of the anodic alumina with the micro-scale, versatile nature of integrated circuits processing. The nanowires can be made by the pressure injection technique, and even more conveniently by electrochemical deposition. The geometry is adequate for 2-point transport measurements on the nanowire arrays, and for fabrication of nanowire-based devices made of several materials and several components. In this context, a fabrication scheme for a thermoelectric device, containing both n-type and p-type legs, is suggested.
2009 IEEE International Electron Devices Meeting (IEDM), 2009
For the first time, we demonstrate control of organic thinfilm transistor's (OTFT) threshold volt... more For the first time, we demonstrate control of organic thinfilm transistor's (OTFT) threshold voltage (V T) by modifying the gate work function. We present a near-room-temperature, fully lithographic process to fabricate integrated pentacene dual V T OTFTs suitable for large-area and flexible mixed signal circuits. Platinum and aluminum are used as the gate metals for the high V T (more depletion-like) and low V T (more enhancement-like) p-channel devices, respectively. The availability of a high V T device enables area-efficient zero-V GS current source loads. We demonstrate positive noise margin inverters which use pico Watts of power and a 3 V supply. Compared to a single V T implementation, the dual V T inverter occupies an area that is 30x smaller, and is 17x faster. These results show that p-channel only organic technologies can produce functional and low-power circuits without integrating a complementary device.
International Electron Devices Meeting 1998. Technical Digest (Cat. No.98CH36217)
Abstract An efficient 3-D numerical tool for modeling and simulating field-emission devices (FED)... more Abstract An efficient 3-D numerical tool for modeling and simulating field-emission devices (FED) is presented. This tool uses an accelerated boundary-element-method (BEM) electrostatics solver and an adaptive explicit integration method. The typical CPU time for ...
MRS Proceedings, 2000
A new approach for the use of porous alumina films as a template for nanofabrication is presented... more A new approach for the use of porous alumina films as a template for nanofabrication is presented. In this process the porous films are prepared on silicon substrates, simplifying both the template fabrication and subsequent processing, and improving the quality of the films and their surfaces. Structural analysis of the film was carried out. Bismuth and bismuth telluride nanowires were prepared by pressure injection and electrochemical deposition, respectively, in alumina films 5-10 μ thick with parallel ordered pores 40 nm in diameter. The films were also patterned by lithography, offering new opportunities for area-selective anodization of non-planar structures. The new approach offers a straightforward method for the fabrication of arrays of nanostructures and their incorporation into electronic and optical devices.
Cockpit Displays IX: Displays for Defense Applications, 2002
The demand for displays with a large number of pixels is being driven by both military and commer... more The demand for displays with a large number of pixels is being driven by both military and commercial applications. Displays with very high information content are expected to have >1Gigapixels, requiring I/O bandwidth well beyond current integrated circuit technology, if display architectures continue as they have in the past. In this paper we present a concept based on latched pixels and data processing at the pixel level that could provide a significant reduction in display bandwidth.
2007 IEEE International Electron Devices Meeting, 2007
Page 1. Uniform High Current Field Emission of Electrons from Si and CNF FEAs Individually Contro... more Page 1. Uniform High Current Field Emission of Electrons from Si and CNF FEAs Individually Controlled by Si Pillar Ungated FETs LF Velasquez-Garcia', B. Adeotil2, Y. Niul2, and A. I. Akinwandel2 ... 1.OE-04 E || 1||PEE Gate Voltage, VG [Volts] 1O0E-05 6 S o intFig. ...
Journal of Display Technology, 2005
... 2, DECEMBER 2005 289 A Lithographic Process for Integrated Organic Field-Effect Transistors I... more ... 2, DECEMBER 2005 289 A Lithographic Process for Integrated Organic Field-Effect Transistors Ioannis Kymissis, Member, IEEE, Akintunde Ibitayo Akinwande, Senior Member, IEEE, andVladimir Bulovic ... 6, pp. 10881090, Feb. 2002. [6] H. Klauk, M. Halik, U. Zschieschang, F ...
IVMC '95. Eighth International Vacuum Microelectronics Conference. Technical Digest (Cat. No.TH8012)
We report the first experimental demonstration of a low voltage, room temperature electron emitte... more We report the first experimental demonstration of a low voltage, room temperature electron emitter that is based on the GaN UV opto-electronic cathode. It consists of an ultra-violet light emitting diode (UV-LED) in direct contact with a photoemitter. The photons generated by the LED have energies - 3.4 eV (the bandgap of GaN). The photons cause photoemission of electrons from
SID Symposium Digest of Technical Papers, 1999
Arrays of molybdenum field emission cones with integrated focusing electrode (IFE‐FEA) were studi... more Arrays of molybdenum field emission cones with integrated focusing electrode (IFE‐FEA) were studied as a potential device structure for Field Emission Displays (FED) that achieve high brightness, high luminous efficiency, and longer lifetime, without loss of resolution. First, an analytical model for the double‐gated conical field emitter was developed and was used for device design. Devices were fabricated and subjected to extensive electrical and some optical testing. The desired focusing effect was observed.
9th International Vacuum Microelectronics Conference
Measurements on arrays of lateral thin-film-edge field emitters are described, including current-... more Measurements on arrays of lateral thin-film-edge field emitters are described, including current-voltage characteristics and results obtained with a high-voltage (10 kV) cathodoluminescent phosphor screen. These devices offer the potential for enhanced emitter lifetime compared to conventional microtips, because one of the gate electrodes protects the emitter edge from ion sputter damage. One goal of this work is to demonstrate the
(CLEO). Conference on Lasers and Electro-Optics, 2005., 2005
Theoretical and experimental results are presented to show that integrated microcavity klystrons ... more Theoretical and experimental results are presented to show that integrated microcavity klystrons can be used to generate high power (1-100 mW) coherent radiation in the 0.5-2.0 THz frequency range at room temperature.
International Technical Digest on Electron Devices Meeting
A self-aligned, refractory metal gate, heterostructure FET process for the fabrication of high-sp... more A self-aligned, refractory metal gate, heterostructure FET process for the fabrication of high-speed digital and mixed digital/analog LSI/VLSI integrated circuits is reported. A 4500-gate 16*16 complex multiplier, a 3800-gate butterfly adder and a four-bit analog-to-digital converter have been demonstrated using MBE (molecular beam epitaxy)-grown heterostructure FET technology. With nominal 1- mu m-gate-length devices, DCFL (direct-coupled FET logic) ring oscillators have propagation delays, of 28 ps/stage at a power dissipation of 1 mW/stage. When the gate length is reduced to 0.5 mu m, DCFL ring oscillators have propagation delays of 17 ps/stage with a power dissipation of 1 mW/stage.<<ETX>>
Journal of The Electrochemical Society, 1987
IEEE Transactions on Electron Devices, 1989
ABSTRACT
IEEE Transactions on Electron Devices, 2011
Analog & digital circuits implemented in a dual threshold voltage (V T) p-channel organic technol... more Analog & digital circuits implemented in a dual threshold voltage (V T) p-channel organic technology are presented. The dual V T organic technology is compatible with large-area and mechanically flexible substrates due to its low processing temperature (≤ 95 • C) and scalable patterning techniques. We demonstrate the first analog & digital organic integrated circuits produced by a dual-gate metal process. The analog circuits are powered by a 5-V supply and include a differential amplifier and a two-stage uncompensated operational amplifier (op-amp). A dynamic comparator is measured to have an input offset voltage of 200 mV and latching time of 119 ms. Both the comparator and the op-amp dissipate 5 nW or less. Area-minimized digital logic is presented. Inverters powered by a 3-V supply were measured to have positive noise margins and consumed picowatts of power. An 11-stage ring oscillator, also powered by a 3-V supply, swings near rail to rail at 1.7 Hz. These results demonstrate dual threshold voltage process feasibility for large-area flexible mixed-signal organic integrated circuits. Index Terms-Comparators, digital integrated circuits, inverters, mixed analog-digital integrated circuits, operational amplifiers (op-amps), organic compounds, thin-film transistors (TFTs).
IEEE Transactions on Electron Devices, 2002
We report 1 nm tip radius, 1 m gate-aperture silicon field emission arrays (FEAs) with turn-on vo... more We report 1 nm tip radius, 1 m gate-aperture silicon field emission arrays (FEAs) with turn-on voltage as low as 14 V. The low turn-on voltage is attributed to the small emitter tip radius, which was achieved by isotropic etching of silicon and low-temperature oxidation sharpening. Optimization of the oxidation sharpening process reduced the tip radius to less than 1 nm and was confirmed by transmission electron microscopy (TEM). The tip radius has a log-normal distribution with a peak at 0.75 nm, an expected value of 1.8 nm, and shape parameter of 0.74 nm. Current-voltage (-) characteristics of the field emission devices are in agreement with Fowler-Nordheim (FN) theory. The extracted tip radius using two-dimensional (2-D) numerical simulation showed good agreement with the TEM measurements. Index Terms-Chemical mechanical polishing (CMP), field emission, Fowler-Nordheim (FN) theory, low-temperature oxidation, transmission electron microscopy (TEM).
IEEE Transactions on Electron Devices, 2010
A fully photolithographic dual threshold voltage (V T) organic thin-film transistor (OTFT) proces... more A fully photolithographic dual threshold voltage (V T) organic thin-film transistor (OTFT) process suitable for flexible large-area integrated circuits is presented. The nearroom-temperature (≤ 95 • C) process produces integrated dual V T pentacene-based p-channel transistors. The two V T 's are enabled by using two gate metals of low (aluminum) and high (platinum) work function. The Al and Pt gate OTFTs exhibit nominally identical current-voltage transfer curves shifted by an amount ΔV T. The availability of a high-V T device enables area-efficient zero-V GS high-output-resistance current sources, enabling high-gain inverters. We present positive noise margin inverters and rail-to-rail ring oscillators powered by a 3-V supply-one of the lowest supply voltages reported for OTFT circuits. These results show that integrating n-and p-channel organic devices is not mandatory to achieve functional area-efficient low-power organic integrated circuits.
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Papers by Akintunde Akinwande