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Studies on Performance Enhancement of Infrared and Terahertz Detectors for Space Applications

Electronic Theses of Indian Institute of Science

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Field Value
 
Title Studies on Performance Enhancement of Infrared and Terahertz Detectors for Space Applications
 
Creator Sumesh, M A
 
Subject Spacecraft
Terahertz Detectors
Photon Detectors
Thermal Detectors
Wave Interaction Detectors
Thin Film Thermistors
Microbolometer
Immersed Bolometers
Terahertz Bolometers
V2O5 Thin Films
Immersed Thermistor Bolometer
THz Detectors
Infrared Detector
Instrumentation
 
Description Currently, the concept of multipurpose spacecrafts is being transformed into many small spacecrafts each of them performing specific tasks and thus leading to the realization of pico and nano satellites. No matter what is the application or size, demand for more number of IR channels for earth observation is ever increasing which necessitates significant reduction in the mass, power requirement and cost of the IR detectors. In this scenario, several order of magnitude mass and power savings associated with uncooled IR arrays are advantageous compared to cooled photon detectors. However the poor speed of response of uncooled microbolometer array devices obstruct the total replacement of cooled detectors in thermal imaging applications. This is especially true when the mission requires 50 m to 100 m ground resolution, in which even the "fastest" micro bolometer arrays turns "too slow" to follow the ground trace when looked from low earth orbit (LEO). Hence there is a great and unfulfilled requirement of faster uncooled detector arrays for meeting the demand for future micro and mini satellite projects for advanced missions. The present thesis describes the systematic studies carried out in development of high performance IR and THz detectors for space applications.
Ge-Si-O thin films are prepared by ion beam sputtering technique with argon (Ar) alone and argon and oxygen as sputtering species, using sputtering targets of different compositions of Ge and SiO2. The deposited thin films are amorphous in nature and have chemical compositions close to that of the target. The study of electrical properties has shown that the activation energy and hence the thermistor constant (β) and electrical resistivity (ρ) are sensitive to oxygen flow rate, and they are the least for thin films prepared with Ar alone as the sputtering species. Different thermal isolation structures (TIS), consisting of silicon nitride (Si3N4) membrane of different thicknesses, Ge-Si-O thin film and, chromium coating on the rear side of the membrane, are prepared by bulk micro-machining technique, whose thermal conductance (Gth) properties are evaluated from the experimentally determined current-voltage (I-V) characteristics. Gth shows non-linear dependence with respect to raise in temperature of thin film thermistor due to Joule heating. The infrared micro-bolometer detectors, fabricated using one of the TIS structures have shown responsivity (
 
Contributor Rao, G Mohan
Sriram, K V
 
Date 2018-06-23T09:35:47Z
2018-06-23T09:35:47Z
2018-06-23
2016
 
Type Thesis
 
Identifier http://etd.iisc.ernet.in/2005/3745
http://etd.iisc.ernet.in/abstracts/4616/G28409-Abs.pdf
 
Language en_US
 
Relation G28409