Far Infrared Mercury-Cadmium-Telluride Photoconductive Detectors

Far Infrared Mercury-Cadmium-Telluride Photoconductive Detectors
Author: C. J. Summers
Publisher:
Total Pages: 16
Release: 1980
Genre:
ISBN:

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Measurements of the excess-electron lifetime, electron concentration, electron mobility, and photoconductive spectral response were performed on HgCdTe alloys with 17 to 24% CdTe between 5 K and 300 K. The temperature dependence of the electron concentration was well fitted by the Kane band model using energy gap determinations from photoconductivity measurements and assuming donor levels with ionization energies between 0 and 7 meV. The level of sample compensation was determined from fits to the electron mobility, which was limited by impurity scattering below 80 K. The temperature dependence of the excess-electron lifetime was analyzed with a photoconductivity theory which includes intrinsic and defect recombination mechanisms and effects from the surface recombination velocity and incident background photon flux. For all sample compositions, a characteristic dependence of electron lifetime on temperature was observed. Above 100 K the lifetime decreases with temperature and is limited by intrinsic Auger recombination. Below 100 K the lifetime decreases with decreasing temperature because of Shockley-Read recombination. A large increase in the lifetime below 40 K is observed and attributed to minority carrier trapping.

Mercury Cadmium Telluride Imagers

Mercury Cadmium Telluride Imagers
Author: A.C. Onshage
Publisher: Elsevier
Total Pages: 457
Release: 1997-06-18
Genre: Technology & Engineering
ISBN: 008052401X

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In two parts, this book describes the evolution of mercury cadmium telluride (HgCdTe) imager structures based upon published patents and patent applications. The first part covers monolithic arrays, and the second part describes hybrid arrays. Each part has 5 chapters, with each document placed in chronological order, with the documents with the earliest priority placed first. Focus has been directed at the steps of manufacturing and structures of imagers. There is an index at the end of the book containing the patent number, the name of the applicant and the date of publication of each cited document. This monograph will serve as a useful summary of the patents and patent applications in the field of mercury cadmium telluride imagers.

Proceedings of the 1990 U.S. Workshop on the Physics and Chemistry of Mercury Cadmium Telluride and Novel Infrared Detector Materials

Proceedings of the 1990 U.S. Workshop on the Physics and Chemistry of Mercury Cadmium Telluride and Novel Infrared Detector Materials
Author: US Workshop on the Physics and Chemistry of Mercury Cadmium Telluride and Novel Infrared Detector Materials (9, 1990, San Francisco, Calif.)
Publisher:
Total Pages:
Release: 1991
Genre:
ISBN:

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Investigation of Resonant-cavity-enhanced Mercury Cadmium Telluride Infrared Detectors

Investigation of Resonant-cavity-enhanced Mercury Cadmium Telluride Infrared Detectors
Author: Justin Wehner
Publisher:
Total Pages: 228
Release: 2007
Genre: Infrared detectors
ISBN:

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[Truncated abstract] Infrared (IR) detectors have many applications, from homeland security and defense, to medical imaging, to environmental monitoring, to astronomy, etc. Increasingly, the wave- length dependence of the IR radiation is becoming important in many applications, not just the total intensity of infrared radiation. There are many types of infrared detectors that can be broadly categorized as either photon detectors (narrow band-gap materials or quantum structures that provide the necessary energy transitions to generate free car- riers) or thermal detectors. Photon detectors generally provide the highest sensitivity, however the small transition energy of the detector also means cooling is required to limit the noise due to intrinsic thermal generation. This thesis is concerned with the tech- nique of resonant-cavity-enhancement of detectors, which is the process of placing the detector within an optically resonant cavity. Resonant-cavity-enhanced detectors have many favourable properties including a reduced detector volume, which allows improved operating temperature, or an improved signal to noise ratio (or some balance between the two), along with a narrow spectral bandwidth. ... Responsivity of another sample annealed for 20 hours at 250C in a Hg atmosphere (ex-situ) also shows resonant performance, but indicates significant shunting due the mirror layers. There is good agreement with model data, and the peak responsivity due to the absorber layer is 9.5×103 V/W for a 100 om ×100 om photoconductor at 80K. An effective lifetime of 50.4 ns is extracted for this responsivity measurement. The responsivity was measured as a function of varying field, and sweepout was observed for bias fields greater than 50 V/cm. The effective lifetime extracted from this measurement was 224 ns, but is an over estimate. Photodiodes were also fabricated by annealing p-type Hg(1x)Cd(x)Te for 10 hours at 250C in vacuum and type converting in a CH4/H2 reactive ion etch plasma process to form the n-p junction. There is some degradation to the mirror structure due to the anneal in vacuum, but a clear region of high reflection is observed. Measurements of current-voltage characteristics at various temperatures show diode-like characteristics with a peak R0 of 10 G measured at 80K (corresponding to an R0A of approximately 104 cm2. There was significant signal from the mirror layers, however only negligible signal from the absorber layer, and no conclusive resonant peaks.