Wyniki wyszukiwania - Biblioteka Nauki

1

Semiconductor detectors and focal plane arrays for far-infrared imaging

100%

Rogalski A.

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tom Vol. 21, No. 4

406-426

EN

The detection of far-infrared (far-IR) and sub-mm-wave radiation is resistant to the commonly employed techniques in the neighbouring microwave and IR frequency bands. In this wavelength detection range the use of solid state detectors has been hampered for the reasons of transit time of charge carriers being larger than the time of one oscillation period of radiation. Also the energy of radiation quanta is substantially smaller than the thermal energy at room temperature and even liquid nitrogen temperature. The realization of terahertz (THz) emitters and receivers is a challenge because the frequencies are too high for conventional electronics and the photon energies are too small for classical optics. Development of semiconductor focal plane arrays started in seventies last century and has revolutionized imaging systems in the next decades. This paper presents progress in far-IR and sub-mm-wave semiconductor detector technology of focal plane arrays during the past twenty years. Special attention is given on recent progress in the detector technologies for real-time uncooled THz focal plane arrays such as Schottky barrier arrays, field-effect transistor detectors, and microbolometers. Also cryogenically cooled silicon and germanium extrinsic photoconductor arrays, and semiconductor bolometer arrays are considered.

2

Optical detectors for focal plane arrays

100%

Rogalski A.

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tom Vol. 12, No. 2

221-245

EN

The paper presents progress in optical detector technologies during the past 25 years. Classification of two types of detectors (photon detectors and thermal detectors) is done on the basis of their principle of operation. The overview of optical material systems and detectors is presented. Also recent progress in different technologies is described. Discussion is focused mainly on current and the most rapidly developing focal plane arrays using: CdZnTe detectors, AlGaN photodiodes, visible CCD and CMOS imaging systems, HgCdTe heterostructure photodiodes, quantum well AlGaAs/GaAs photoresistors, and thermal detectors. The outlook for near-future trends in IR technologies is also presented.

3

HgCdTe photodiodes versus quantum well infrared photoconductors for long wavelength focal plane arrays

100%

Rogalski A.

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tom Vol. 6, No. 4

279-294

EN

Recent trends in infrared detectors are towards large, electronically addressed two-dimensional arrays. In the long wavelength infrared (LWIR) spectral range HgCdTe focal plane arrays (FPAs) occupy dominant position. However, the slow progress in the development of large LWIR photovoltaic HgCdTe infrared imaging arrays and the rapid achievements of novel semiconductor heterostructure systems have made it necessary to foresee the future development of different material techmologies in fabrication large of FPAs. Among the competing technologies in LWIR are the quantum well infrared photoconductors (QWIPs) based on lattice matched GaAs / AlGaAs and strained layer InGaAs / AlGaAs material systems. This paper compares the technical merits of two IR detector arrays technologies ; photovoltaic HgCdTe and QWIPs. It is clearly shown that LWIR QWIP cannot compete with HgCdTe photodiode as the single device, especially at higher temperature operation (> 70 K) due to fundamental limitations associated with intersubband transitions. However, the advantage of HgCdTe is less distinct in temperature range bellow 50 K due to problems involved in a HgCdTe material (p-type doping, Shockley-Read recombination, trap-assisted tunnelling, surface and interface instabilities). Even though that QWIP is a photoconductor, several its properties such as high impedance, fast response time, long integration time, and low power consumption, well comply requirements of fabrication large FPAs. Due to the high material quality at low temperature, QWIP has potential advantages over HgCdTe for very LWIR (VLWIR) FPA applications in terms of the array size, uniformity, yield and cost of the systems.

4

Recent progress in HgCdTe infrared detector technology

100%

Rogalski A.

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tom Vol. 6, No. 1

47-67

EN

At present effors in infrared (IR) detector ressearch are directed towards improving the performance of single element devices and large electronically scanned arrays, and to increase their operating temperature. Another important aim is to make IR detectors cheaper and more convenient to use. Among different types of materials used in IR detector technology, HgCdTe ternary alloy has privileged position. HgCdTe remains the most important material for infrared photodetectors despite of numerous attempts to replace it with alternative materials. None of these competitors can compete in terms of fundamental properties. In addition, HgCdTe exhibits nearly constant lattice parameter that is of extreme importance for new devices based on complex heterostructures. In the paper investigations of the performance of HgCdTe photodiodes operated at short wavelength IR (SWIR), 1-3 um ; medium wavelength IR (MWIR), 3-5 um ; and long wavelength IR (LWIR), 8-14 um spectral regions are presented. The operating temperature for HgCdTe detectors is hogher than for other types of photo detectors. HgCdTe detectors with background limited performance operate with thermoelectric coolers in the medium wavelength range, while the long wavelenght detectors operate at ≈100 K. HgCdTe is haracterized by high absorption coefficient and quantum efficiency and relatively low thermal generation rate compared to other detectors. Despite serious competition from alternative technologies and slower progress than expected, HgCdTe is unlikely to by seriously challenged for high-performance applications, applications requiring multispectral capability and fast response. The long term picture could change as a result of current research activity in low-cost, lightweight, small in size and convenient to use of uncooled detectors.

5

Terahertz detectors and focal plane arrays

100%

Rogalski A.

|

2010

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tom Vol. 51, nr 4

93-108

EN

Terahertz (THz) detectors play increasing role in different areas of human activities (e.g., security, biological, drugs and explosions detection, imaging, astronomy applications, etc.). In the paper, issues associated with the development and exploitation of THz radiation detectors is discussed. The basic physical phenomena and the recent progress in both direct and heterodyne detectors are described. More details concerning Schottky barrier diodes, pair braking detectors, hot electron mixers and field-effect transistor detectors, where links between THz devices and modern technologies such as micromachiningare underlined. Also the operational conditions of THz detectors and their upper performance limits are reviewed.

PL

Znaczenie detektorów terahertzowych wzrasta w różnych obszarach aktywności człowieka (dla przykładu: w ochronie obiektów i ludzi; w detekcji środków biologicznych, narkotyków, odczynników trujących, środków wybuchowych zobrazowaniu, w zastosowaniach astronomicznych, etc.). W pracy przedstawiono sposób działania i postęp technologiczny w rozwoju różnych typów detektorów terahertzowych zarówno w detekcji bezpośredniej jak i heterodynowej. Więcej uwagi poświęcono detektorom z barierami Schottky'ego, detektorom nadprzewodzącym i detektorom wykorzystującym tranzystory polowe, których rozwój uwarunkowany jest postępem w technologii mikromechaniki półprzewodnikowej.

6

Advanced technologies in development of optical detectors

100%

Rogalski A.

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tom Vol. 45, nr 12

12-19

PL

W pracy przedstawiono postęp w rozwoju detektorów promieniowania optycznego w ciągu ostatniego ćwierćwiecza. Omówiono podstawy działania dwu grup detektorów (termicznych i fotonowych) stosowanych w szerokim zakresie widma optycznego. Przedyskutowano nowe tendencje rozwojowe w technologii i konstrukcji detektorów promieniowania X, promieniowania g[gamma] promieniowania ultrafioletowego i podczerwonego. Przedstawiono przykłady najbardziej spektakularnych osiągnięć w tym zakresie, dotyczące detektorów z CdZnTe, detektorów ultrafioletowych z AIGaN, matryc CCD i CMOS zakresu widzialnego, detektorów heterozłączowych z HgCdTe, fotorezystorów ze studni kwantowych układu AIGaAs/GaAs i bolometrów krzemowych.

EN

The paper presents progress in optical detector technologies during the past 25 years. Classification of two types of detectors (photon detectors and thermal detectors) is done on the basis of their principle of operation. The overview of optical material systems and detectors is presented. Also recent progress in different technologies is described. Discussion is focused mainly on current and the most rapidly developing focal plane arrays using: CdZnTe detectors, AIGaN photodiodes, visible CCD and CMOS imaging systems, HgCdTe heterostructure photodiodes, quantum well AIGaAs/GaAs photoresistors, and thermal detectors.

7

History of infrared detectors

100%

Rogalski A.

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tom Vol. 20, No. 3

279-308

EN

This paper overviews the history of infrared detector materials starting with Herschel's experiment with thermometer on February 11th, 1800. Infrared detectors are in general used to detect, image, and measure patterns of the thermal heat radiation which all objects emit. At the beginning, their development was connected with thermal detectors, such as thermocouples and bolometers, which are still used today and which are generally sensitive to all infrared wavelengths and operate at room temperature. The second kind of detectors, called the photon detectors, was mainly developed during the 20th Century to improve sensitivity and response time. These detectors have been extensively developed since the 1940's. Lead sulphide (PbS) was the first practical IR detector with sensitivity to infrared wavelengths up to ~3 µm. After World War II infrared detector technology development was and continues to be primarily driven by military applications. Discovery of variable band gap HgCdTe ternary alloy by Lawson and co-workers in 1959 opened a new area in IR detector technology and has provided an unprecedented degree of freedom in infrared detector design. Many of these advances were transferred to IR astronomy from Departments of Defence research. Later on civilian applications of infrared technology are frequently called "dual-use technology applications." One should point out the growing utilisation of IR technologies in the civilian sphere based on the use of new materials and technologies, as well as the noticeable price decrease in these high cost technologies. In the last four decades different types of detectors are combined with electronic readouts to make detector focal plane arrays (FPAs). Development in FPA technology has revolutionized infrared imaging. Progress in integrated circuit design and fabrication techniques has resulted in continued rapid growth in the size and performance of these solid state arrays.

8

Photoresponse of GaN p-n junction and Schottky barrier ultraviolet photodetectors

63%

Małachowski M. J. , Rogalski A.

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tom Vol. 6, No. 2

141-149

EN

At present, the main effors in fabrication of UV photodetectors are directed to GaN Schottky barriers and p-n junction photodiodes. The future development of UV photodetectors will be dominated by complex band gap heterostructures using 3- dimensional gap and doping engineering. AlGaN exhibits extreme flexibility, it can be tailored for the optimised detection at important region of UV spectrum, and multicolor devices can be easily constructed. A study of GaN Schottky barriers (with a n-type material) and p-n junction photodiodes in ultraviolet range are carried out. Due to the fact that the built-in voltage of a Schottky diode is smaller than that of a p-n junction, the depletion region width is smaller than that of p-n junction. Special attention has been devoted to an analysis of the current responsivities of both types of detectors. Owing to relative simplicity in fabrication of Schottky barriers, they can be more promising than p-n junction detectors, especially in the case of low doping or/and thin front layer ensuring the entire depletion of the n-type layer.

9

Infrared Devices And Techniques (Revision)

63%

Rogalski A. , Chrzanowski K.

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nr 4

10

Czy silniki indukcyjne muszą być trójfazowe?

63%

Rogalski A. , Bieńkowski K.

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tom Nr 67

81-84

EN

Stator winding of induction machines has to produce sinusoidal magnetic flux. In typical construction this aim is realised by complicated and expensive double-layer, three-phase windings. In spite of applying such measures, higher harmonics exists in magneto motive force, which causes additional losses, vibrations and noises. Amplitude of fundamental harmonics is decreasing too. Applying of polyphases windings in induction machines supplying by frequency converters permits to enlarge the winding coefficient for fundamental harmonics and to decrease amplitude of higher harmonics. It causes cheaper and simpler construction of windings with single-layer diametrical coils and minimisation of copper mass in engine, as well as losses, vibrations and noises. Decreasing of current flowing in one transistor key will be an additional advantage because it allows construction of greater power machines. Comparison of winding coefficients of three-phase winding and five-phase winding and comparison of higher harmonics spectrum in MMF is presented in this paper.

11

Detection of optical radiation

63%

Rogalski A. , Bielecki Z.

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12

Model kompleksowy silnika reluktancyjnego przełączalnego z toczącym się wirnikiem

63%

Kamiński G. , Rogalski A.

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tom z. 116

11-47

PL

Układ maszynowy charakteryzujący się małą prędkością obrotową i dużym momentem napędowym jest realizowany najczęściej w postaci silnika wysokoobrotowego i przekładni mechanicznej obniżającej prędkość obrotową (zwiększającej moment napędowy). Alternatywnym rozwiązaniem może być silnik z toczącym się wirnikiem. W Instytucie Maszyn Elektrycznych Politechniki Warszawskiej zbudowano i przeprowadzono badania prototypu jak i kompleksowego modelu matematycznego (składającego się z trzech sieci: reluktancyjnej, impedancyjnej i równań ruchu), silnika reluktancyjnego przełączalnego z toczącym się wirnikiem. Wyniki badań, jak i proces tworzenia modelu kompleksowego są przedstawione w tym artykule.

EN

A prototype of a rolling rotor switched reluctance motor and the results investigations carried out in the Institute of Electric Machines of the Warsaw University of Technology are presented. The formation and the structure (construction) of the total model containing: reluctance, impedance and dynamics networks and the results of mathematical model tests are presented in this paper.

13

Barrier infrared detectors

51%

Martyniuk P. , Kopytko M. , Rogalski A.

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tom Vol. 22, No. 2

127-146

EN

In 1959, Lawson and co-workers publication triggered development of variable band gap Hg1-xCdxTe (HgCdTe) alloys providing an unprecedented degree of freedom in infrared detector design. Over the five decades, this material system has successfully fought off major challenges from different material systems, but despite that it has more competitors today than ever before. It is interesting however, that none of these competitors can compete in terms of fundamental properties. They may promise to be more manufacturable, but never to provide higher performance or, with the exception of thermal detectors, to operate at higher temperatures. In the last two decades a several new concepts of photodetectors to improve their performance have been proposed including trapping detectors, barrier detectors, unipolar barrier photodiodes, and multistage detectors. This paper describes the present status of infrared barrier detectors. It is especially addressed to the group of III-V compounds including type-II superlattice materials, although HgCdTe barrier detectors are also included. It seems to be clear that certain of these solutions have merged as a real competitions of HgCdTe photodetectors.

14

Detektory barierowe : nowe trendy

51%

Martyniuk P. , Kopytko M. , Rogalski A.

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tom Vol. 57, nr 9

62--65

PL

W artykule omówiono nowe trendy w rozwoju wysokotemperaturowych – nie wymagających chłodzenia kriogenicznego – barierowych detektorów podczerwieni. Przedstawiono podstawy teoretyczne, podstawową strukturę typu nBn, jak również dokonano przeglądu materiałów wykorzystywanych do wytwarzania detektorów barierowych pod względem granicznych wartości prądu ciemnego. Przedstawiono osiągi detektorów barierowych wytwarzanych z supersieci-II rodzaju materiałów grupy AIIIBV InAs/GaSb i InAs/InAsSb. W przypadku InAs/InAsSb szacowania teoretyczne wskazują na lepsze osiągi niż te uzyskiwane dla układu InAs/GaSb. Nie pominięto materiałów objętościowych z grupyAIIIBV: InAs, InAsSb i InGaAsSb, jak również dominującego obecnie HgCdTe. Detektory barierowe związków grupyAIIIBV, zarówno z materiałów litych jak i z supersieci-II typu, stanowią realną alternatywę dla HgCdTe do zastosowań wysokotemperaturowych, choć najniższe graniczne wartości prądu nadal uzyskuje się dla struktur z HgCdTe.

EN

In the paper we discussed the new trends in higher operating temperature – exhibiting no requirements related to the cryogenic cooling – the barrier IR detectors. We presented basic theory, simple nBn structure, and reviewed the materials used for the nBn detectors in terms of the utmost dark current. The performance was presented for type-II superllatices InAs/GaSb and InAs/InAsSb. Theoretical simulations indicate that T2SLs InAs/InAsSb exhibits lower SRH generation recombination rates in comparison to the InAs/GaSb. The performance of the bulk InAsSb and HgCdTe materials was also presented. TheAIIIBV bulk and type-II superlattices barrier detectors could be treated as an alternative to the HgCdTe detectors for higher operating temperature conditions. The utmost dark current was found for HgCdTe nBn barrier detectors.

15

Investigations of transverse stability of semi-displacement ships

51%

Brzoska E. , Grygorowicz M. , Rogalski A.

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tom Vol. 9, nr 4

3-7

EN

In this paper results of experimental model investigations of transverse stability of semi-displacement ships are presented, aimed at determination of influence of their speed and hull form parameters on transverse stability. On the basis of these results algorithms were elaborated which take onto account righting arm changes in function of ship speed, heel angle and geometrical hull parameters. The algorithms can be used for assessment of transverse stability of ships of the kind.

16

Barierowe struktury detekcyjne : nowe możliwości

51%

Martyniuk P. , Kowaleski A. , Gawron W. , Rogalski A.

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tom Vol. 53, nr 11

102-105

PL

Detektory promieniowania podczerwonego z wąską przerwą energetyczną wymagają chłodzenia celem ograniczenia prądów ciemnych generowanych w strukturze detekcyjnej wśród których najważniejszymi są: procesy generacyjno - rekombinacyjne Shockley-Read-Halla i procesy Augera. Obecnie, zwiekszenie temperatury pracy urządzeń detekcyjnych bez ograniczenia ich osiągów jest głównym celem wielu zespołów badawczych. Procesy generacyjno - rekombinacyjne Augera można ograniczyc poprzez budowę urządzęń detekcyjnych z supersieci II rodzaju (type II superlattice - T2SLs) z związków AIIIBV należących do rodziny 6.1 L. Implementacja barier do struktur detekcyjnych pozwala zredukować niekorzystny wpły procesów Shockley-Read-Halla. Ograniczenie wpływu obu mechanizmów pozwoli zwiększyć temperaturę pracy detektora. Artykuł przedstawia osiągi unipolarnych detektorów nBn z T2SLs InAs/GaSb/B- AI₀.₂Ga₀.₈Sb i HgCdTe oraz ich potencjalne możliwości w rozwoju detektorów promieniowania podczerwonego.

EN

The narrow band gap infrared detectors require cryogenic cooling to suppress dark current, which is typically limited by Shockley-Read-Hall (SRH) and Auger generation-recombination processes. Currently, increasing the operating temperature of the infrared detection systems without sacrificing its performance remains to be a crucial objective of the research groups. Intrinsic Auger thermal generation recombination process could be controlled by implementation of the type II superlattices (T2SLs) AIIIBV 6.1 L family to the detectors architecture while extrinsic SRH process could be suppressed by the barrier's incorporation into detector's structure respectively. Both SHR and Auger suppression lead to increase of the device's operating temperature. The paper reports on the unipolar barrier infrared detector (UBIRD) medium wavelength infrared (MWIR) HgCdTe nBn/B-n type and T2SLs nBn lnAs/GaSb/B-AI₀.₂Ga₀.₈Sb detector's photoelectrical performance and their potential possibilities in the field of infrared detectors development.

17

Enhanced numerical analysis of current-voltage characteristics of long wavelength infrared p-on-n HgCdTe photodiodes

51%

Jóźwikowski K. , Kopytko M. , Rogalski A.

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2010

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tom Vol. 58, nr 4

523-533

EN

An enhanced original computer programme is applied to explain in detail the current-voltage characteristics of p-on-n long wavelength infrared (LWIR) HgCdTe photodiodes. The computer programme solves the system of non-linear continuity equations for carriers and Poisson equations. In the model ideal diode diffusion, generation-recombination, band-to-band tunnelling, trap-assisted tunnelling, and impact ionization are included as potential limiting mechanisms in the photodiodes. It is a clearly explained influence of extrinsic doping of an active device region on dark current-voltage characteristics and on R0A product of HgCdTe photodiodes in a wide region of temperature and wavelengths. Special attention is directed to the dependence of tunnelling probability on the shape of potential barrier within the depletion region. The theoretical predictions are compared with experimental data of high quantity photodiodes published in the available literature.

18

Comparison of performance limits of the HOT HgCdTe photodiodes with colloidal quantum dot infrared detectors

45%

Rogalski A. , Kopytko M. , Martyniuk P. , Hu W. , Rogalski A. , Kopytko M. , Martyniuk P. , Hu W.

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nr 4

19

The predictions of resistance and propulsion for 4 types of ships

45%

Brzoska E. , Grygorowicz M. , Rogalski A. , Stasiak J. , Szantyr J.

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tom S 1

34-38

EN

In this paper the predictions of resistance and propulsion for 4 types of ships: container carrier, oil product tanker, ro-ro vessel and river-sea vessel included in the EUREKA "Baltecologicalship" project E!2772 are presented. All the above ships were designed by the SINUS Enterprise Ltd. The scope of the research covers: experimental measurement of ship resistance in calm water, determination of resistance increment in irregular waves and computational powering prediction for POD propulsors. The experiments were conducted in the Laboratory of the Department of Underwater Technology, Hydromechanics and Design of Ships, Faculty of Ocean Engineering and Ship Technology, Gdansk University of Technology.

20

Two-colour HgCdTe infrared detectors operating above 200 K

38%

Rutkowski J. , Madejczyk P. , Piotrowski A. , Gawron W. , Jóźwikowski K. , Rogalski A.

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tom Vol. 16, No. 3

321-327

EN

The performance of dual waveband HgCdTe photodiodes fabricated using metaloorganic chemical vapour deposition operated at high temperatures is presented. The effect of additional separating layer on the quantum efficiency and cross-talk of the photodiodes is analyzed. The photodiodes with cutoff wavelengths up to 6 um, good RoA product, and high quantum efficiency at 200 K have been demonstrated. The temperature dependence of the differential resistance is discussed. It is shown that the multilayer heterojunction P-n-N-n-P structure operating in a simultaneous mode has better performance than a structure operating in a sequential mode.