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Dive into the research topics where Jeremy A. Theil is active.

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Featured researches published by Jeremy A. Theil.


Journal of Non-crystalline Solids | 2002

a-Si:H photodiode technology for advanced CMOS active pixel sensor imagers

Jeremy A. Theil; Rick D. Snyder; David W. Hula; Kirk Lindahl; Homayoon Haddad; Jim Roland

Abstract Hydrogenated amorphous silicon (a-Si:H) holds the promise of realizing three-dimensional semiconductor integrated circuits by placing the photodiode above the pixel control circuitry rather than in-plane with it. This has the obvious advantages of enabling large die-size reduction and higher light collection efficiency compared to standard crystalline silicon arrays. We have developed a photodiode array technology that is fully compatible with 0.35 μm CMOS process flows to produce image sensors arrays with 10-bit dynamic range that are 30% smaller than comparable standard crystalline silicon photodiodes. These sensors have 50% higher sensitivity, and two times lower dark current when compared to bulk silicon sensors of the same design. The various methods of interconnection of the diode to the array and their advantages will be presented. Diode leakage currents as low as 30 pA / cm 2 have been measured. The effect of doped layer thickness and concentration on quantum efficiency (as high as 80% around 560 nm), and the effect of a-Si:H defect concentration on diode performance will be discussed.


MRS Proceedings | 1997

Thermal Stability of a-C:F,H Films Deposited by Electron Cyclotron Resonance Plasma Enhanced Chemical Vapor Deposition

Jeremy A. Theil; Francoise Mertz; Micah Yairi; Karen Seaward; Gary W Ray; Gerrit Kooi

Amorphous carbon films grown with fluorohydrocarbons can be grown to have dielectric constant values around 2.0. The behavior of these films when subjected to thermal excursion is studied. We have investigated material deposited in an ECR plasma, and find that the F:H ratio of the gas mixture is a good guide to material properties. Films deposited at 5°C were placed in a vacuum chamber at 400°C as long as 60 minutes. The film thickness, dielectric constant, and infrared absorption spectrum change with the F:H ratio of the incoming gas and thermal cycling. It was found that the dielectric constant and loss tangent decrease upon heating and that there is an apparent increase in C=C groups. As expected, as the F:H ratio increases, the dielectric constant and thermal stability decrease. Good thermal stability is shown for F:H ratios of 1.5, which result in films with a dielectric constant of ∼2.4 after heating.


Journal of Vacuum Science & Technology B | 2003

Fabrication and characterization of silicon nanocrystals by thermal oxidation of a-Si:H films in air

Sandeep Kohli; Jeremy A. Theil; Rick D. Snyder; Christopher D. Rithner; Peter K. Dorhout

Hydrogenated amorphous silicon (a-Si:H) and Si–O–H heterogeneous thin films have been examined for their potential to photoluminesce. In this study, 50 nm a-Si:H films were deposited and oxidized to understand how film morphology affects their optical properties. Glancing angle x-ray diffraction (XRD), x-ray reflectivity, x-ray photoelectron spectroscopy, optical absorption spectroscopy in the wavelength range 250–1000 nm, and Fourier transform infrared measurements were used to complement room temperature photoluminescence (PL) studies. The results are discussed in light of the standard models for room temperature visible PL for a-SiOx:H films and silicon nanocrystals. The PL peak at 1.6 eV arises from silicon nanocrystals. Modeling this band to estimate the quantum dot size indicates that the mean silicon crystallite diameter is ∼5 nm, while XRD analysis gives ∼9±1 nm. The discrepancy in the estimation of crystallite size by the XRD method and PL analysis is attributed to the columnar growth of the sili...


IEEE\/ASME Journal of Microelectromechanical Systems | 2006

Characterization of a Dipole Surface Drive Actuator With Large Travel and Force

Manu Agarwal; David T. Dutton; Jeremy A. Theil; Qing Bai; Evelyn Par; Storrs T. Hoen

This paper presents a detailed study of the dynamic performance of an electrostatic surface drive actuator. This actuator is capable of producing 50 gs of acceleration with 70 mum travel at a 30 V bias. For the first time, air operation of a dipole surface actuator is demonstrated and we describe a fabrication process that has increased device yield more than an order of magnitude. Detailed characterization of the actuator performance is enabled by the integration of a capacitive position sensor that provides 0.5 Aring resolution in a 1-Hz bandwidth. The performance of this actuator is compared with other micromachined actuators and with more conventional milliactuators


MRS Proceedings | 2003

Leakage Current Behavior in Common I-Layer A-SI:H P-I-N Photodiode Arrays

Jeremy A. Theil

Hydrogenated amorphous silicon photodiode arrays form the basis of monolithic threedimensional integrated circuit sensor technology. In these arrays, the intrinsic a-Si:H layer covers the entire area to maximize light collection. One technique by which the pixel diode is defined, is to pattern the bottom contact layer independently of the intrinsic layer. One of the most important characteristics of any diode array, however, is that the dark-state reverse bias leakage currents must be as low as possible to minimize diode noise. This study examines the leakage currents associated with the pixelated array. These structures are unique in that the edge of the diode is defined by the local electric field between diodes, rather than the physical surface of an a-Si:H film. The effect of the diode edge has been found to induce a field-dependent component to the reverse bias leakage current. For example, diodes with 5500A i-layer, have a junction leakage of 14 to 20 pA/cm 2 ,a t 5.0 x1 0 4 V/cm, while the pixel edge-dependent current component can be as high as 30 pA/cm 2 . In addition, it will be shown that the i-layer thickness and junction doping plays a key role in determining the behavior of the leakage currents.


Wave Optics and VLSI Photonic Devices for Information Processing | 2001

Performance of a-Si:H Photodiode Technology-Based Advanced CMOS Active Pixel Sensor Imagers

Jeremy A. Theil; Homayoon Haddad; Rick D. Snyder; Mike Zelman; David W. Hula; Kirk Lindahl

Amorphous silicon photodiode technology is a very attractive option for image array integrated circuits because it enables large die-size reduction and higher light collection efficiency than c-Si arrays. The concept behind the technology is to place the photosensing element directly above the rest of the circuit, thus eliminating the need to make areal tradeoffs between photodiode and pixel circuit. We have developed an photodiode array technology that is fully compatible with a 0.35 um CMOS process to produce image sensors arrays with 10-bit dynamic range that are 30% smaller than comparable c-Si photodiode arrays. The work presented here will discuss performance issues and solutions to lend itself to cost-effective high-volume manufacturing. The various methods of interconnection of the diode to the array and their advantages will be presented. The effect of doped layer thickness and concentration on quantum efficiency, and the effect of a-Si:H defect concentration on diode performance will be discussed. The photodiode dark leakage current density is about 80 pA/cm2, and its absolute quantum efficiency peaks about 85% at 550 nm. These sensors have 50% higher sensitivity, and 2x lower dark current when compared to bulk silicon sensors of the same design. The cell utilizes a 3 FET design, but allows for 100% photodiode area due to the elevated nature of the design. The VGA (640 X 480), array demonstrated here uses common intrinsic and p-type contact layers, and makes reliable contact to those layers by use of a monolithic transparent conductor strap tied to vias in the interconnect.


Proceedings of SPIE, the International Society for Optical Engineering | 2001

XGA resolution full-video microdisplay using light-emitting polymers on a silicon active matrix circuit

Howard E. Abraham; Homer Antoniadis; Daniel B. Roitman; Kyle Frischknecht; Travis N. Blalock; Ken A. Nishimura; Thomas A. Knotts; Jeremy A. Theil; Chris Bright; Jeffrey N. Miller; Ronald L. Moon

Capable self-emissive polymers are being developed for use as emitting materials for a variety of display applications. This paper describes the use of standard CMOS integrated circuit silicon wafer technology along with a spin-cast polyfluorene-base polymer emissive layer, to demonstrate an XGA resolution, full video microdisplay. The silicon chip drive circuitry (Analog Pixel-APIX) is described along with results from our efforts to optimize the reflective anode, the semitransparent cathode process, and emissive cell construction. The 1024 X 768 pixel display achieves 200 Cd/m2 brightness at low power (<50 mW) with fast 1 usec response times. In addition, we summarize future directions to achieve color and the need to incorporate a production- worthy seal layer on microdisplays manufactured on silicon wafers.


MRS Online Proceedings Library Archive | 2005

Reduction of Residual Transient Photocurrents in A Si:H Elevated Photodiode Array Based Cmos Image Sensors

Jeremy A. Theil

While a-Si:H based elevated photodiode arrays hold the promise of superior performance and lower cost CMOS-based image sensors relative to those based upon crystalline silicon photodiodes, the one area where a-Si:H based sensor performance has not been as good is in image lag. This problem is only exacerbated by Staebler Wronski Effect induced junction degradation. Image lag is caused by residual charge from photocurrents trapped within the junction once the light source is removed and can be measured for several seconds, even under continuous applied reverse bias. It is seen both in constant and variable bias pixel architectures. However, by carefully controlling a-Si:H junction bias conditions, it is possible to significantly reduce these transient photocurrents. This article will describe how the photocurrent decay time exponent can be reduce by almost an order of magnitude. Finally the physical causes behind image lag in a-Si:H based photodiode arrays will be discussed.


MRS Proceedings | 2004

Suppression of Staebler-Wronski Effect Induced Electrical Crosstalk in a-Si:H-Based Image Sensors

Jeremy A. Theil

Hydrogenated amorphous silicon photodiodes have been considered for use in array-based image sensors. They promise to significantly reduce the size and cost of CMOS image sensors, while offering the promise of improved pixel sensitivity. However, Staebler-Wronski Effect (SWE) based electrical crosstalk degradation has been a major concern in their acceptance, due to degraded spatial contrast and color fidelity. Since the SWE is a fundamental mechanism of a Si:H, solutions to this issue must look to ways of mitigating the SWE on diode array performance rather than elimination of SWE. In order to study electrical crosstalk, a novel device structure that inhibits light from reaching portions of the a-Si:H/dielectric interface was designed and fabricated to directly measure interpixel leakage currents. Results from these structures indicate that edge leakage can be a significant contributing component to the measured signal. In addition, a CMOS-compatible structure to suppress electrical crosstalk was designed and fabricated. Results from these structures demonstrate suppression of crosstalk up to lateral electric fields of at least 2 x 104 V/cm. Such suppression is adequate for densely packed minimum-size pixel arrays. Aspects of the design and implementation of the structure will also be discussed.


Optical Science and Technology, SPIE's 48th Annual Meeting | 2003

Nanocrystal formation in thermally oxidized and annealed a-Si:H films and SiOxNy films (x=0.17; y=0.07)

Sandeep Kohli; Jeremy A. Theil; Rick D. Snyder; Christopher D. Rithner; Peter K. Dorhout

Silicon nanocrystals have been prepared in thermally oxidized hydrogenated amorphous silicon (a-Si:H) and annealed silicon-rich oxynitride (SRON) films with [O/Si]=0.17 [N/Si]=0.07, in the temperature range 400-800°C and 850-1150°C respectively. Glancing Angle X-ray Diffraction (GAXRD) measurements show the presence of silicon nanocrystals embedded in silicon oxide films. Warren-Averbach Analysis of GAXRD data indicates the presence of ~9 nm silicon crystallites in a-Si:H films oxidized at 800°C. Room temperature photo-luminescence (PL) was observed from silicon nanocrystals embedded in oxidized a-Si:H films. Modeling the PL data indicates the presence of 6 nm silicon nanocrystals. This discrepancy is attributed to the columnar growth of silicon nanocrystals in thermally oxidized a-Si:H films. Silicon nanocrystals were not formed by thermal oxidation of SRON films under similar reaction conditions. However, silicon nanocrystals could be fabricated by annealing SRON films for 4 h in vacuum over the temperature range 850-1150°C. Silicon crystallite sizes remained constant (~4 nm) for films annealed below 1050°C and increased to 9 nm for films annealed at 1150°C. The presence of nitrogen played an important role in the silicon nanocrystal precipitation in SRON films. While the nanocrystal formation in a-Si:H films was due to oxidation and crystallization progressing simultaneously in the films, nanocrystal formation in SRON films appears to be due to the high temperature precipitation of excess silicon in the film.

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