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 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 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 New Ternary Alloy Systems for Infrared Detectors written by Antoni Rogalski and published by SPIE Press. This book was released on 1994 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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 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 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 Investigation of a Normal Incidence High Performance P Type Strained Layer In 0 3 Ga 0 7 As In 0 52 Al 0 48 As Quantum Well Infrared Photodetector written by and published by . This book was released on 1994 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: During this reporting period, we have made excellent progress towards the program goals. A significant achievement was made in the development of a new compressionally strained p-type GaAs/InGaAs QWIP grown on GaAs by MBE. This new QWIP achieved two color detection with detective peaks at 8.9 microns and 8. 4 microns in the LWIR band and 5.5 microns in the MWIR band. This detector is under background limited performance (BLIP) at temperatures up to 70 K. The measured responsivity were found to be 24 mA/W and 45 mA/W for the two LWIR peaks respectively, while a responsivity of 13 mA/W was found for the MWIR peak; all at T=75 K. Additional characterization on the tensile strain InGaAs/InAlAs on InP P-QWIP has been performed and the results are summarized in this report. Currently, we are investigating other possible p-type QWIP structures with different performance parameters. These include a new dual strained InGaAs/ InAlAs p-type QWIP. Additional consideration is being given towards the reliability of p-type contacts and the strained layer material for these QWIP structures P-type strained layer InGaAs/InAlAs Quantum Well Infrared Photodetectors (QWIPs), Intersubband absorption, Dark current, Responsivity, Detectivity.

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 Corrugated Quantum Well Infrared Photodetector Focal Plane Array Test Results written by and published by . This book was released on 1999 with total page 13 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 Design of Quantum Well Infrared Photodetectors written by Janet Lin Pan and published by . This book was released on 1999 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quantum Well Infrared Photodetector FPA written by and published by . This book was released on 1994 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: The AT & T/Rockwell team met all the objectives of this collaborative program; AT & T supplied the QWIP detector arrays and Rockwell subsequently fabricated hybrid focal plane arrays using available high performance CMOS multiplexers, tested the hybrids, performed breadboard imaging demonstrations and delivered several hybrid FPAs. Eighteen hybrids were fabricated and evaluated. The collaboration yielded significant improvements in QWIP FPA performance and reliability and many milestones including: first BLIP LWIR FPA sensitivity demonstration at low photon backgrounds (1 x 10 to the 12th photons/sq cm-sec) with the GaAs-based quantum well infrared photodetector (QWIP) technology, high LWIR FPA pixel operability. NE Delta T's as low as 5 mK at LWIR imaging backgrounds at f/1.4 and temperatures consistent with mechanical coolers (approx. 65K), increased coupling efficiency by over an order of magnitude; achieved effective quantum efficiency of approx. 10% with low crosstalk. effective quantum efficiencies of up to 30% under flood illumination, though with high crosstalk, mean D* of 1 x 10 to the 14th cm-Hz to the 1/2/w at 3.0 x 10 to the 9th photons/sq cm-sec background at 32.5K operating temperature with 98% operability. maximum temperature for 9.5 microns m FPA BLIP sensitivity as high as 62K, excellent hybrid reliability by mechanically thinning the QWIP, responsivity nonuniformity 3% rms, thus enabling83 dB dynamic range.

Download or read book Magnetically Tuned Wide Band Quantum Well Infrared Photodetectors written by and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The electron eigenstates of double quantum well system in an in-plane magnetic field are calculated accurately using the density-functional theory, which includes the Coulomb interaction between electrons. The absorption coefficient as a function of the probe photon energy is further calculated using the self-consistent-field theory, which takes into account many-body effects on the optical intersubband transitions. The dependence of the absorption spectra on the magnetic field, temperature, electron density, well and middle-barrier widths, quantum-well symmetry, and electric field has been studied extensively. It provides an unconventional approach for designing a tunable wide-band quantum well infrared photodetectors by applying an in-plane magnetic field.

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 Simulation of Performance of Quantum Well Infrared Photodetectors written by and published by . This book was released on 2005 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis the performance of a step quantum well infrared photodetector, designed by Kevin Lantz (June 2002) and experimentally studied by Michael Touse (September 2003) and Yeo Hwee Tiong (December 2004), was simulated in Matlab using the transfer matrix method. The results, obtained by the Matlab problem, are compared with the experimental results, in an attempt to make inferences about the optimum way of designing QWIP detectors. Simulation of the above implies numerical solution of the Schroedinger equation, using algorithms and methods, which give accurate results. In our approach, the transfer matrix method (TMM) was used with exponentials and Airy functions to represent the solutions to Schroedinger equation under zero and non-zero bias, respectively. The calculated results were compared with the experimental data and found to provide a good agreement which validated the accuracy of the model employed. In the final section of the thesis we examine and simulate in Matlab the application of the extended Kalman filtering (EKF) to an infrared photodetector as a target tracking mechanism to both maneuvering and non-maneuvering targets. When we used one sensor for tracking, the results were reliable provided that the target did not maneuver. In the case of a maneuvering target the results were significantly improved when we used both sensors for tracking.