Biometric system based on one single large area a-SiC:H p-i-n photodiode

AbstractBased on the Laser Scanned Photodiode (LSP) image sensor we present an optical fingerprint reader for biometric authentication. The device configuration and the scanning system are optimized for this specific purpose.The scanning technique for fingerprint acquisition is improved and the effects of the probe beam size, wavelength and flux, the scan time and modulation frequency on image contrast and resolution will be analyzed under different electrical bias. An optical model of the image acquisition process is presented and supported by a two dimensional simulation.Results show that a trade-off between read-out parameters (fingerprint scanner) and the biometric sensing element structure (p-i-n structure) are needed to minimize the cross talk between the fingerprint ridges and the fingerprint valleys. In the heterostructures with wide band gap/low conductivity doped layers the user-specific information is detected with a good contrast while the resolution of the sensor is around 20 νm. A further increase in the contrast is achieved by slightly reverse biasing the sensor with a sensitivity of 6.5 νWcm-2 and a flux range of two orders of magnitude.

Download Full-text

A new CLSP Sensor for Image Recognition and Color Separation

MRS Proceedings ◽

10.1557/proc-715-a4.3 ◽

2002 ◽

Vol 715 ◽

Cited By ~ 10

Author(s):

M. Vieira ◽

M. Fernandes ◽

A. Fantoni ◽

P. Louro ◽

R. Schwarz

Keyword(s):

Color Image ◽

Wide Band ◽

Large Area ◽

Wide Band Gap ◽

Color Recognition ◽

Color Separation ◽

Color Sensors ◽

Generation Region ◽

Image Shape ◽

Dimensional Simulation

AbstractLarge area p-i-n a-SiC:H heterostructures are used as LSP color sensors. For reading out the color signals, three appropriated voltages have to be successively applied in order to combine afterwards the information to yield a color image. The highly resistive and wide band gap doped layers confine the photogenerated carriers at the illuminated regions and driven by the scanner extract information on the image shape and intensity. The bias voltage controls the potential profile across the main generation region leading to color sensitivity. As the positive applied voltage increases the reversed electrical field in the bulk shifts toward the main generation regions, and successively suppresses the ac component of the photocurrent at each primary color allowing color extraction. The device performance is analyzed and the scanning technique for color separation improved. The influence of the optical and electrical bias on image contrast, resolution and color extraction is discussed. A physical model for image and color recognition is presented and supported by a two dimensional simulation.

Download Full-text

Integrated technologies and the problem of creation of large-area silicone carbide devices for high-power converters

MATEC Web of Conferences ◽

10.1051/matecconf/201823901019 ◽

2018 ◽

Vol 239 ◽

pp. 01019

Author(s):

Tatiana Ilicheva ◽

Eugeny Panyutin

Keyword(s):

Computer Modelling ◽

Probability Distributions ◽

Wide Band ◽

Power Devices ◽

Large Area ◽

Wide Band Gap ◽

Reverse Branch ◽

Wide Band Gap Semiconductors ◽

Current Characteristics ◽

Silicone Carbide

We consider limitations typical for semiconductor devices of up-to-date converter equipment based on silicon and silicone technologies. The reasons for processing complexities in creating the hardware components of heavy-current devices based on wide-band-gap semiconductors are analyzed. Possible approach to production of large area SiC-diodes and thyristors is formulated, which at post-processing stage allows performing modification of their voltage-current characteristics (VCC) and increasing in its non-linearity coefficient. Based on the concept of integrated power devices containing mesa-elements with VCC with random parameters, the possibility of sequential automated exclusion of those single “non-standard” micro-devices to adversely impact on general voltage-current characteristics of an array is considered. Algorithm is briefly described, and computer modelling of transformation of the reverse branch of integrated VCC occurring in the course of such modification is provided, which made it possible to establish relationship between the typical probability distributions of impurity (including in the presence of dislocations) and certain features of final VCC.

Download Full-text

SiC-Si Grooved Surface Bonding

MRS Proceedings ◽

10.1557/proc-681-i5.6 ◽

2001 ◽

Vol 681 ◽

Author(s):

Tatiana S. Agrunova ◽

Igor V. Grekhov ◽

Lioudmila S. Kostina ◽

Alexander G. Tur'yanskii ◽

Igor V. Pirshin ◽

...

Keyword(s):

Wide Band ◽

Structural Perfection ◽

Large Area ◽

Wide Band Gap ◽

X Ray ◽

Bipolar Devices ◽

Grooved Surface ◽

Bonding Technology ◽

Interfacial Potential ◽

Surface Bonding

ABSTRACTSiC Lely platelets and SiC epilayers on large area SiC substrates were directly bonded to non-oxidized grooved surface silicon wafers in order to obtain structures prospective for the design of power bipolar devices with wide band-gap emitter junctions. The reported capabilities of grooved interfaces to reduce elastic strain and intrinsic sources of an interfacial potential barrier were utilized. The influence of surface morphology on the structural perfection of the bonded samples was studied in detail by X-ray and AFM techniques. As compared to traditional bonding technology, experimental data showed an easier smooth-to-grooved surface bonding accomplished in the formation of the boundary with better continuity and strength. For 2 in. diameter SiC wafers with root mean square height of roughness σ=16 Å and lateral coherence length L=1.8 μm bonding continuity not smaller than 90% was reached, while the crystals with σ=30 Å, L=5 μm failed to bond to Si even under an external force.

Download Full-text

A Large-Area Transferable Wide Band Gap 2D Silicon Dioxide Layer

ACS Nano ◽

10.1021/acsnano.6b03929 ◽

2016 ◽

Vol 10 (8) ◽

pp. 7982-7989 ◽

Cited By ~ 26

Author(s):

Christin Büchner ◽

Zhu-Jun Wang ◽

Kristen M. Burson ◽

Marc-Georg Willinger ◽

Markus Heyde ◽

...

Keyword(s):

Silicon Dioxide ◽

Band Gap ◽

Wide Band ◽

Large Area ◽

Wide Band Gap ◽

Silicon Dioxide Layer

Download Full-text

Growth, characterization and optoelectronic applications of pure-phase large-area CsPb2Br5 flake single crystals

Journal of Materials Chemistry C ◽

10.1039/c7tc04834c ◽

2018 ◽

Vol 6 (3) ◽

pp. 446-451 ◽

Cited By ~ 45

Author(s):

Zhaojun Zhang ◽

Yanming Zhu ◽

Weiliang Wang ◽

Wei Zheng ◽

Richeng Lin ◽

...

Keyword(s):

Band Gap ◽

Single Crystals ◽

Wide Band ◽

Large Area ◽

Wide Band Gap ◽

Growth Characterization ◽

Pure Phase ◽

Potential Applications ◽

Deep Uv ◽

Optoelectronic Applications

Wide band gap CsPb2Br5 flake single crystals have been successfully obtained and demonstrated to have potential applications in deep-UV photodetection.

Download Full-text

TEM and cathodoluminescence of precipitates in II-VI semiconductors

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104509 ◽

1988 ◽

Vol 46 ◽

pp. 488-489

Author(s):

Joanna L. Batstone

Keyword(s):

Crystal Growth ◽

Band Gap ◽

Local Strain ◽

Wide Band ◽

Optoelectronic Device ◽

Wide Band Gap ◽

Bulk Crystal Growth ◽

Transmission Electron ◽

Device Applications ◽

Stoichiometry Control

Interest in II-VI semiconductors centres around optoelectronic device applications. The wide band gap II-VI semiconductors such as ZnS, ZnSe and ZnTe have been used in lasers and electroluminescent displays yielding room temperature blue luminescence. The narrow gap II-VI semiconductors such as CdTe and HgxCd1-x Te are currently used for infrared detectors, where the band gap can be varied continuously by changing the alloy composition x.Two major sources of precipitation can be identified in II-VI materials; (i) dopant introduction leading to local variations in concentration and subsequent precipitation and (ii) Te precipitation in ZnTe, CdTe and HgCdTe due to native point defects which arise from problems associated with stoichiometry control during crystal growth. Precipitation is observed in both bulk crystal growth and epitaxial growth and is frequently associated with segregation and precipitation at dislocations and grain boundaries. Precipitation has been observed using transmission electron microscopy (TEM) which is sensitive to local strain fields around inclusions.

Download Full-text

Electron microscopic characterization of diamond thin films and substrates for diamond heteroepitaxial growth

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100154937 ◽

1989 ◽

Vol 47 ◽

pp. 592-593

Author(s):

J.B. Posthill ◽

R.P. Burns ◽

R.A. Rudder ◽

Y.H. Lee ◽

R.J. Markunas ◽

...

Keyword(s):

Thin Films ◽

Wide Band ◽

Deposition Process ◽

Heteroepitaxial Growth ◽

Electron Microscopic ◽

Wide Band Gap ◽

Lattice Matching ◽

Different Types ◽

Diamond Thin Films

Because of diamond’s wide band gap, high thermal conductivity, high breakdown voltage and high radiation resistance, there is a growing interest in developing diamond-based devices for several new and demanding electronic applications. In developing this technology, there are several new challenges to be overcome. Much of our effort has been directed at developing a diamond deposition process that will permit controlled, epitaxial growth. Also, because of cost and size considerations, it is mandatory that a non-native substrate be developed for heteroepitaxial nucleation and growth of diamond thin films. To this end, we are currently investigating the use of Ni single crystals on which different types of epitaxial metals are grown by molecular beam epitaxy (MBE) for lattice matching to diamond as well as surface chemistry modification. This contribution reports briefly on our microscopic observations that are integral to these endeavors.

Download Full-text