Download or read book Tunable Bandwidth Quantum Well Infrared Photo Detector TB QWIP written by Mihail Giannopoulos and published by . This book was released on 2003-12-01 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis a tunable bandwidth quantum well photo- detector (TB- QWIP) is fabricated and experimentally characterized. The designed detector is based on the Stark effect with two quantum step wells arranged opposite to each other to simultaneously achieve both blue- and red-shift of the absorption peak for either direction of the bias. The characterization of the TB-QWIP is based on absorption measurement with Fourier Transform Infra Red (FTIR) spectroscopy, current versus applied voltage (I-V) measurement with a semiconductor parameter analyzer, and photo current spectroscopy. The measured IR absorption peaks found at room temperature 8.8 microns and 10.0 microns, are in good agreement with designed values.
Download or read book Design of a Voltage Tunable Broadband Quantum Well Infrared Photodetector written by Atakan Konukbay and published by . This book was released on 2002-06 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this thesis is to design a quantum well infrared detector with tunable spectral bandwidth. The tunability of the bandwidth is achieved by using the linear Stark effect for the ground to first excited state transition in an asymmetric quantum well. The position of the absorption peak is dependent on the direction of the electric field, and therefore it can be either blue or red shifted by changing the direction of the field. If two identical asymmetric quantum wells are arranged opposite each other, we can obtain both the blue and red shift for either direction of the bias. This method can produce broader peaks with tunable bandwidths proportional to the applied field. A program was developed to calculate the energy levels and wavefunctions of an arbitrary quantum well. The program was used to design a step quantum well capable of detecting infrared in the 8-12 micrometers band. The validity of the approach was verified by comparison with experimental data and found to have a good agreement. The designed step well was used to create a tunable bandwidth detector. The analysis showed that the bandwidth could be tuned to more than twice the peak width. The numerical simulation indicates the possibility of manufacturing a tunable bandwidth infrared detector by using step quantum wells.
Download or read book High Responsivity Tunable Step Quantum Well Infrared Photodetector written by Yeo Hwee Tiong and published by . This book was released on 2004-12-01 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, the performance of a step quantum well infrared photodetector (QWIP), which was designed to detect a laser spot at 1.05 m and IR radiation between 9.5 m to 10.5 m, was evaluated. In the far infrared (FIR), the maximum responsivity of the test detector at 10 K was measured at 1.02 A/W with a peak wavelength of 10.3 m under a negative bias of 0.83 V. The D* at background limited infrared performance (BLIP) was measured at 8.0x10(9) cm square root Hz/W with 180 degrees field of view. The BLIP temperature was found to be about 55 K. In addition, the FIR detection wavelength found shift with the amount of bias across the device. The amount of shift observed was 0.21 meV/ kvcm-1 which is due to linear Stark effect associated with the step quantum well. The quantum well infrared detectors made of square quantum wells found to have an order of magnitude lower Stark shift originated from second order effects. This suggests that the step well infrared detector can have applications in tunable wavelength infrared detectors.
Download or read book Quantum Well Infrared Photodetectors written by Harald Schneider and published by Springer. This book was released on 2006-10-18 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Addressed to both students as a learning text and scientists/engineers as a reference, this book discusses the physics and applications of quantum-well infrared photodetectors (QWIPs). It is assumed that the reader has a basic background in quantum mechanics, solid-state physics, and semiconductor devices. To make this book as widely accessible as possible, the treatment and presentation of the materials is simple and straightforward. The topics for the book were chosen by the following criteria: they must be well-established and understood; and they should have been, or potentially will be, used in practical applications. The monograph discusses most aspects relevant for the field but omits, at the same time, detailed discussions of specialized topics such as the valence-band quantum wells.
Download or read book Voltage Tunable Two Color Quantum Well Infrared Photodetector written by and published by . This book was released on 2003 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Significant progress was made to further advance the quantum well infrared photodetector (QWIP) technology in two areas: 1) designating demonstrating, and understanding voltage tunable two-color QWIPs, and 2) understanding the light coupling mechanism in the so-called quantum grid infrared photodetectors. We have also been working on imprint technology to create pillars which can be used to enhance the performance of the photodetectors. The NIL molds with different period and different shape of the pillars have been created. Implementation of the small pillars to photo-detectors are in progress.
Download or read book Fabrication of Tunable Quantum Well Infrared Photodetectors QWIP Polarization Sensitive QWIPs and Enhanced Coupling Grating Structures written by and published by . This book was released on 2005 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project investigates the properties of intersubband reduced dimension devices based on quantum wells and quantum dots, which could be used for infrared detection. In the past few years, there has been active research on studying the performance characteristics of mid-wave infrared (MWIR, 3-5 m) and long-wave infrared (LWIR, 8-12 m) applications. Present-day photon detectors in this wavelength range need to be cooled to liquid nitrogen temperature or below. Quantum dot detectors are expected to display low dark current, large detectivity and better response at elevated temperature due to the longer lifetime of excited electrons due to greatly suppressed electron-phonon scattering. The responsivity and specific detectivity of QDIPs is significantly lower than those observed in mercury cadmium telluride (MCT) detectors. However, due to difficulties with the epitaxial growth of mercury based compounds, material defects cause problems with uniformity and operability across an array that continues to plague MCT focal plane arrays. QDIPs, on the other hand, are based on a comparatively mature GaAs technology and the uniformity of their response suggests that they can be incorporated into large area focal plane arrays (FPAs).
Download or read book The Physics of Quantum Well Infrared Photodetectors written by K. K. Choi and published by World Scientific. This book was released on 1997 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past, infrared imaging has been used exclusively for military applications. In fact, it can also be useful in a wide range of scientific and commercial applications. However, its wide spread use was impeded by the scarcity of the imaging systems and its high cost. Recently, there is an emerging infrared technology based on quantum well intersubband transition in III-V compound semiconductors. With the new technology, these impedances can be eliminated and a new era of infrared imaging is in sight. This book is designed to give a systematic description on the underlying physics of the new detectors and other issues related to infrared managing.
Download or read book Multi Color Quantum Well Infrared Photodetectors for Mid Long and Very Long Wavelength Infrared Applications written by Sheng S. Li and published by . This book was released on 2002 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantum well infrared photodetectors (QWIPs) have been widely investigated for the 3 - 5 micrometers mid-wavelength infrared (MWIR) and 8 - 12 micrometers long-wavelength infrared (LWIR) atmospheric spectral windows as well as very long wavelength infrared (VLWIR: lambda(sub c)> 14 micrometers) detection in the past decade. The mature III-V compound semiconductor growth technology and the design flexibility of device structures have led to the rapid development of various QWIP structures for infrared focal plane arrays (FPAs) applications. In addition to the single-color QWIP with narrow bandwidth, the multi-color QWIP required for advanced IR sensing and imaging applications have also been emerged in recent years. Using band gap engineering approach, the multi-color (2, 3, and 4- color) QWIPs using multi-stack quantum wells with different well width and depth and voltage-tunable triple-coupled quantum well (TCQW) structure for detection in the MWIR, LWIR, and VLWIR bands have been demonstrated. In this paper, the design, fabrication, and characterization of a voltage-tunable 2-stack 3-color QWIP for MW/LW/LW IR detection and a 3-stack 3-color QWIP for detection in the water, ozone, and CO2 atmospheric blocking bands are depicted.
Download or read book Development of High Performance Multicolor Quantum Well Infrared Photodetectors and Studies of Enhancing Light Coupling and Radiation Effects in QWIPs written by and published by . This book was released on 1999 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this report, we present the design, fabrication, and characterization of several high performance multi-color and broadband quantum well infrared photodetectors (QWIPs) for both MWIR and LWIR applications. The report covers tasks performed during the period from March 3, 1998 through July 10, 1999. A very high sensitivity, high-strain, multi-color triple-coupled (TC-) QWIP using InGaAs/AlGaAs/InGaAs material systems has been developed in this project for LWIR multi-color detection. A two-stack InGaAs/AlGaAs/InGaAs TC-QWIP and InGaAs/AlGaAs TC-QWIP has been developed for the LWIR and MWIR dual-band detection. In addition, a high-strain InGaAs/GaAs TC-QWIP with and without two-dimensional (2-D) grating coupler has been designed, fabricated, and characterized for the LWIR detection. This device shows very high responsivity under 450 back-illumination. Several broadband (BB-) QWIPs have been developed for the LWIR detection. These include (1) two-stack, five-well n-type InGaAs/AlGaAs broadband (BB-) QWIPs with 3- and 7-period QWs in the unit cell, (2) 3- and 4-well n-type BB-QWIPs, and (3) two 3- and 4- well p-type BB-QWIPs. In addition, a three-stack InGaAs/AlGaAs/InGaAs BB TC-QWIP grown on GaAs substrate has been developed for LWIR detection, which has a FWHM spectral bandwidth twice larger than the single-stack TC-QWIP. Finally, a MWIR InGaAs/InAlAs TC-QWIP grown on InP substrate, operating up to T = 116K with excellent device performance, has also been demonstrated. Four journal papers and six conference papers have been published and presented from this work.
Download or read book Corrugated Quantum Well Infrared Photodetector Focal Plane Array Test Results written by and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The corrugated quantum-well infrared photodetector (C-QWIP) uses total internal reflection to couple normal incident light into the optically active quantum wells. The coupling efficiency has been shown to be relatively independent of the pixel size and wavelength thus making the C-QWIP a candidate for detectors over the entire infrared spectrum. The broadband coupling efficiency of the C-QWIP makes it an ideal candidate for multiwavelength detectors. We fabricated and tested C-QWIP focal plane arrays (FPAs) with cutoff wavelengths of 11.2 and 16.2 micrometers. Each FPA has 256 x 256 pixels that are bump-bonded to a direct injection readout circuit. Both FPAs provided infrared imagery with good aesthetic attributes. For the 11.2-micrometers FPA, background-limited performance (BLIP) was observed at 60 K with f/3 optics. For the 16.2-micrometers FPA, BLIP was observed at 38 K. Besides the reduction of dark current in C-QWIP structures, the measured internal quantum efficiency (eta) remains to be high. The values for responsivity and quantum efficiency obtained from the FPA results agree well with those measured for single devices.
Download or read book Investigation of Multicolor and Simplified Quantum Well Infrared Photodetectors for MWIR and LWIR Detection written by and published by . This book was released on 2000 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this research program, we have investigated a four-stack, four-color quantum well infrared photodetector (QWIP), and studied the voltage distribution and temperature effect in this four-color QWIP. We have conducted a study on the quantum confined Stark-effect in an n-type QWIP. We have performed theoretical studies of the intersubband optical transitions in quantum dots and the design of GaAs/InGaAs and InAs/InAlAs quantum dot infrared photodetectors (QDIPs) for MWIR and LWIR detection. A new QWIP for very long wavelength infrared (VLWIR) applications has been investigated for 14-16 (micrometer) detection. Specific issues concerning device physics, detector design and device performance of the VLWIR QWIP are addressed. A VLWIR QWIP has been designed, fabricated and characterized. Two high performance multi-color, broadband QWIPs using digital graded superlattice barriers (DGSLB) for long wavelength infrared (LWIR) and broadband (BB) infrared detection have been demonstrated. We have also developed a high performance broadband (BB) In(0.26) Ga(0.74) As/Al(x) Ga(1-x)As QWIP using a linearly graded (LGB) Al(x) Ga(1-x) As barrier for LWIR detection. Theoretical study on the enhancement of quantum efficiency in a QWIP by using photonic crystal structure has also been carried out in this report.
Download or read book Multicolor Quantum Well Infrared Photodetectors written by Meimei Tidrow and published by . This book was released on 1998 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multicolor infrared (IR) detectors are very important to advanced IR sensor systems. An IR detector with multicolor capability can offer a better target discrimination, tracking, and identification, as well as temperature determination. Multicolor IR sensors are also very useful in industry for gas leakage detection, chemical analysis, and for environmental sensing and control. As the IR technology continues to advance, there is a growing demand of multicolor IR detectors for advanced IR sensor systems. Quantum well infrared photodetector (QWIP) is one of the competing technologies that shows very promising potential in infrared detection and imaging. One major advantage of QWIPs is its multicolor detection capability and voltage tunability. Several approaches of achieving multicolor detection, detailed device structures, and performance of multicolor QWIPs will be presented. The multicolor voltage tunability, simultaneous detection capability, and the Stark Shift effect for fine tuning of the peak detection wavelength will be discussed.
Download or read book Voltage Tunable Two Color Infrared Detection Using Semiconductor Superlattices written by and published by . This book was released on 2003 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: We demonstrate a voltage tunable two-color quantum-well infrared photodetector (QWIP) that consists of multiple periods of two distinct AlGaAs/GaAs superlattices separated by AlGaAs blocking barriers on one side and heavily doped GaAs layers on the other side. The detection peak switches from 9.5 mu m under large positive bias to 6 mu m under negative bias. The background-limited temperature is 55 K for 9.5 mu m detection and 80 K for 6 mu m detection. We also demonstrate that the corrugated-QWIP geometry is suitable for coupling normally incident light into the detector.
Download or read book Voltage Tunable Two color Quantum well Infrared Photodetectors written by Amlan Majumdar and published by . This book was released on 2002 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Multi Band GaAs AlGaAs Quantum Well Infrared Photodetector QWIP Focal Plane Arrays written by and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The GaAs/AlGaAs based Quantum Well Infrared Photodetectors (QWIPs) afford greater flexibility than the usual extrinsically doped semiconductor IR detectors because the wavelength of the peak response and cutoff can be continuously tailored over any wavelength between 6-20 micrometers. The spectral band width of these detectors can be tuned from narrow (DELTAlamba/lamba 10 %) to wide (DELTAlamba/lamba 50 %) allowing various applications. Also, QWIP offers multi-color infrared cameras which is capable of simultaneously acquiring images in different infrared bands. Each pixel of such array consists of vertically stacked, independently readable, QWIP detectors sensitive in different narrow infrared bands. In this article, we discuss the development and results of the 640x512 dual-band and four-band QWIP FPAs.
Download or read book GUIA do produtor written by and published by . This book was released on 1996 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Administração direta; Secretaria de política grícola-SPA; Abastecimento agropecuário; Secretaria de desenvolvimento rural-SDR; Assistência técnica e extensão rural; Conservação de solo e água; Cooperativismo e associativismo rural; Informação agrícola; Infra-estrutura rural; Mecanização e aviação agrícolas; Produção animal; Produção vegetal; Secretaria de defesa agropecuária-SDA; Defesa animal; Inspeção de produtos de origem animal; Defesa e inspeção vegetal; Endereços (EMATER, DEA, Convênios de classificação vegetal, Criadores de bovinos e laboratórios); Comissão especial de recursos-CER; Comissão executiva do plano da lavoura cacaueira-CEPLAC; Instituto naional de meteorologia-INMET; Administração indireta; Instituto nacional de colonização e reforma agrária-INCRA; Companhia Nacional de Abastecimento-CONAB; Empresa brasileira de pesquisa agropecuária -EMBRAPA; Companhia de colonização do nordeste-COLONE.
Download or read book Characterization and Analysis of a Multicolor Quantum Well Infrared Photodetector written by and published by . This book was released on 2006 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents analysis and characterization of performance of a newly designed, multicolor quantum well infrared photodetector (QWIP). Specifically, it focuses on a detector capable of detecting infrared emissions in the near infrared (NIR), mid-wavelength infrared (MWIR), and long-wavelength infrared (LWIR). Through photocurrent spectroscopy and performance analysis, this prototype detector can be classified and prepared for possible future use within the U.S. Armed Forces. Certain military applications require a highly accurate, reliable, sensitive, and multispectral infrared detector to identify targets and ensure mission success. By designing and fabricating a multicolor quantum well infrared photodetector, simultaneous detection of targets in the near infrared, mid-wavelength infrared and long-wavelength infrared is possible using only one detector. In addition, power and cooling requirements for quantum well infrared detectors makes them suitable for use in the field.
