Advances in small-pixel, large-format α-Si bolometer arrays

Schimert, Thomas R.; Hanson, Charles M.; Brady, John F.; Fagan, T.; Taylor, Marcus; McCardel, W.; Gooch, R.; Gohlke, Martin; Syllaios, A. J.

doi:10.1117/12.818576

Cited by 24 publications

(16 citation statements)

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“…More gain can be obtai− ned through improvement of the thermistor material; its TCR and R. A promising approach is the development of lower resistance a−Si/a−SiGe thin films [89,90]. The TCR of Si alloy has been increased to »3.9%/K from a baseline of 3.2%/K without an increase in material 1/f−noise.…”

Section: R Ff Tcr V G R I Biasmentioning

confidence: 99%

History of infrared detectors

Rogalski

2012

Opto-Electronics Review

425

207

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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.

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Section: R Ff Tcr V G R I Biasmentioning

confidence: 99%

History of infrared detectors

Rogalski

2012

Opto-Electronics Review

425

207

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“…Hydrogenated amorphous silicon (aSi:H) deposited by plasma is a mature material used as thermo-sensing film in commercial infrared detectors as micro-bolometer arrays [1,2], since it is fully compatible wit the CMOS technology, has a very high activation energy (E a ≈ 1 eV) and as consequence a very high thermal coefficient of resistance, TCR (α ≈ -0.13 K -1 ), which results in pixel devices with very high responsivity values. However a-Si:H has a very low room temperature conductivity (σ RT ≤ 1x10 -9 (Ωcm) -1 ) , providing a very high pixel resistance (R pixel ≥ 10…”

Section: Introductionmentioning

confidence: 99%

Measurements of thermal characteristics in silicon germanium un‐cooled micro‐bolometers

Moreno

Ambrosio

Torres

et al. 2010

Phys. Status Solidi (c)

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We present a study of the thermal characteristics of an infrared detector (un‐cooled micro‐bolometer), based on an amorphous silicon germanium film (a‐SixGey:H), deposited by plasma at low temperature (∼ 300 °C) and compatible with the standard CMOS technology. These films have been studied due to their high performance characteristics as high activation energy (Ea≈ 0.37 eV), high temperature coefficient of resistance (TCR≈ ‐0.047 K‐1) and moderate room temperature conductivity (σRT≈ 2x10‐5Ω cm), which provides a moderate pixel resistance (Rcell≈3.5x108Ω). We have used two simple methods to calculate the thermal characteristics of the micro‐bolometer. The thermal conductance (Gth) has been obtained from the electrical I(U) characteristics in the range where self heating due to bias is not presented. The temperature dependence of the electrical resistance and as well the temperature dependence of the thermal resistance have been obtained by measuring the I(U) characteristics in the device at different temperature values. Finally the results of both methods have been compared. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…The increased concentration is needed to accommodate the potential difference, caused by the bandgap offset. At the same time, the concentration outside the SiGe layer is reduced below the background doping level of 1×10 16 cm -3 , in order to maintain the total net charge, given by the acceptor dopant profile. The resulting effect is that the low doped Si regions exhibit large resistivity, while the top and contact region and the SiGe layer itself will have little contribution to the total resistance of the structure.…”

Section: Materials For High Tcrmentioning

confidence: 99%

“…IR imaging technology can be separated in two main realms; cooled detectors working with direct photon detection in the infrared wavelength, and uncooled thermal IR detectors that are based on heat absorption and the electrical measurement of the resulting temperature change of the detector membrane. Today, the vast majority of commercially available IR imaging systems utilizes uncooled IR bolometer focal plane array technology [5][6][7][8][9][10][11][12][13][14][15][16][17]. Uncooled IR bolometer focal plane arrays consist of matrixes of small suspended bolometer sensor membranes that are placed on top of CMOS-based integrated electronic circuits as depicted in Figure 1a.…”

Section: Introductionmentioning

confidence: 99%

Micromechanical Process Integration and Material Optimization for High Performance Silicon-Germanium Bolometers

Malm¹,

Kolahdouz²,

Forsberg

et al. 2012

MRS Proc.

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Semiconductor-based thermistors are very attractive sensor materials for uncooled thermal infrared (IR) bolometers. Very large scale heterogeneous integration of MEMS is an emerging technology that allows the integration of epitaxially grown, high-performance IR bolometer thermistor materials with pre-processed CMOS-based integrated circuits for the sensor read-out. Thermistor materials based on alternating silicon (Si) and silicon-germanium (SiGe) epitaxial layers have been demonstrated and their performance is continuously increasing. Compared to a single layer of silicon or SiGe, the temperature coefficient of resistance (TCR) can be strongly enhanced to about 3 %/K, by using thin alternating layers. In this paper we report on the optimization of alternating Si/SiGe layers by advanced physically based simulations, including quantum mechanical corrections. Our simulation framework provides reliable predictions for a wide range of SiGe layer compositions, including concentration gradients. Finally, our SiGe thermistor layers have been evaluated in terms of low-frequency noise performance, in order to optimize the bolometer detectivity.

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Advances in small-pixel, large-format α-Si bolometer arrays

Cited by 24 publications

References 0 publications

History of infrared detectors

History of infrared detectors

Measurements of thermal characteristics in silicon germanium un‐cooled micro‐bolometers

Micromechanical Process Integration and Material Optimization for High Performance Silicon-Germanium Bolometers

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