Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

Sorted by: relevance · author · university · dateNew search

You searched for subject:(mid infrared wavelengths). Showing records 1 – 2 of 2 total matches.

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters


McMaster University

1. Mohammedy, Farseem Mannan. Growth, Fabrication and Characterization of Metamorphic InGaSb Photodetectors for Application in 2.0 μm and Beyond.

Degree: PhD, 2008, McMaster University

Sensing systems for mid-infrared wavelengths (2 to 5 μm) have important applications in biomedical, atmospheric and process gas monitoring systems. For lack of a suitable substrate, the full potential of GaSb-based materials, which are particularly suitable for operating in these wavelengths, are not completely realized. Hence, metamorphic growth technology, that allows the growth of semiconductor epilayers of arbitrary composition on any substrate, has been explored for antimony materials in this research. This makes the growth of device layers, containing arbitrary composition of GaSb-based materials, possible on commercially available 6"-GaAs substrates, and thereby reducing fabrication cost. Metamorphic growth of In(0.15)Ga(0.85)Sb was achieved using gas-source molecular beam epitaxy by growing compositionally graded ln(x)Ga(1-x)Sb buffer layers on a GaSb substrate. The effects of growth temperature on the quality of the metamorphic buffer layers along with the etching issues (both wet and dry) of GaSb-based materials were studied. Homo-junction n-i-p and p-i-n diodes were fabricated on In(0.15)Ga(0.85)Sb metamorphic layers. The dark current and its temperature dependence were measured and the extraction of area and perimeter components of dark current was done. The modeling of the components of dark current suggests that the diode currents were dominated by surface leakage. Surface passivation by silicon nitride and polyimide were investigated and our findings suggest that the former resulted in a better passivated surface. Responsivity measurements show that In(0.18)Ga(0.82)Sb diodes, metamorphically grown on GaSb substrates, have a cut-off wavelength of 2270 nm. Finally, hole (β) and previously unreported electron (α) ionization coefficients, at room temperature and 90° C, were extracted from these structures. The results show that α>β for ln(0.10)Ga(0.90)Sb for both temperatures. These photodetectors can be implemented m practical receiver systems for mid-infrared applications, such as atmospheric CO2 and methane detection at 2.0 μm. The possibility of growing antimony-based device layers on larger substrates, paves the way for future optoelectronic receiver systems operating at longer wavelengths, where both the photodetector and the amplifier can be integrated in the same module.

Thesis

Doctor of Philosophy (PhD)

Advisors/Committee Members: Deen, M. Jamal, Thompson, David A., Electrical and Computer Engineering.

Subjects/Keywords: mid-infrared wavelengths; metamorphic growth technology; photodetectors; antimony

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Mohammedy, F. M. (2008). Growth, Fabrication and Characterization of Metamorphic InGaSb Photodetectors for Application in 2.0 μm and Beyond. (Doctoral Dissertation). McMaster University. Retrieved from http://hdl.handle.net/11375/16689

Chicago Manual of Style (16th Edition):

Mohammedy, Farseem Mannan. “Growth, Fabrication and Characterization of Metamorphic InGaSb Photodetectors for Application in 2.0 μm and Beyond.” 2008. Doctoral Dissertation, McMaster University. Accessed January 19, 2020. http://hdl.handle.net/11375/16689.

MLA Handbook (7th Edition):

Mohammedy, Farseem Mannan. “Growth, Fabrication and Characterization of Metamorphic InGaSb Photodetectors for Application in 2.0 μm and Beyond.” 2008. Web. 19 Jan 2020.

Vancouver:

Mohammedy FM. Growth, Fabrication and Characterization of Metamorphic InGaSb Photodetectors for Application in 2.0 μm and Beyond. [Internet] [Doctoral dissertation]. McMaster University; 2008. [cited 2020 Jan 19]. Available from: http://hdl.handle.net/11375/16689.

Council of Science Editors:

Mohammedy FM. Growth, Fabrication and Characterization of Metamorphic InGaSb Photodetectors for Application in 2.0 μm and Beyond. [Doctoral Dissertation]. McMaster University; 2008. Available from: http://hdl.handle.net/11375/16689


University of Florida

2. Moerchen, Margaret. Location and Origin of Dust in Circumstellar Debris Disks A Mid-Infrared Imaging Study.

Degree: PhD, Astronomy, 2008, University of Florida

Approximately one third of A-type stars host dusty disks beyond the expected timescales for dissipation of the primordial disk material. The primordial dust particles may either be blown out by radiation pressure from the star or they may experience destructive collisions that generate smaller particles that are then blown out of the system. We infer from the sustained presence of the dust that it must be resupplied through collisions of already-formed planets and planetesimals or through the sublimation of cometary bodies, and systems with such dust are called debris disks. Since the 1984 discovery of the debris disk Vega, observations of circumstellar debris disks have revealed the presence planetary systems that would otherwise have remained unknown. In this work, we set out to ?nd asymmetric structures in debris disks that would indicate a physical process sculpting the disk, such as a catastrophic planetesimal collision that generates a bright region of newly-formed dust, or a clumpy pattern comprised of dust that is trapped in an orbital resonance with a giant planet. We obtained high spatial resolution ( < 0.5') images of the thermally emitting dust in 21 debris disk candidates (some of which are now known not to be debris disks), and in most cases we did not detect any brightness asymmetry nor was the source even spatially resolved. However, among the resolved disks, we have discovered several structures that may be analogous to those in our own solar system, such as a potential asteroid belts (in Zeta Lep) and a snow line (in HD 32297). One brightness asymmetry is seen, in the disk of HR 4796A, and we have determined that the bright side of the disk is also hotter than the opposite side. We review the possible origins of such a temperature asymmetry in the dust disk, such as pericenter glow and resonant trapping, and this investigation is ongoing. More generally, two disk archetypes are observed among all of the disks in this sample: Kuiper Belt analogs (four) and asteroid belt analogs (two). The asteroid belt analog is a new archetype among the overall group ( < 20) of spatially resolved debris disks, and its impact on descriptions of planetary system architecture will be better understood as the sample of resolved disks grows. ( en ) Advisors/Committee Members: Telesco, Charles M. (committee chair), Packham, Christophe C. (committee member), Kehoe, Thomas J. (committee member), Tan, Jonathan (committee member), Min, Kyoungwon Kyle (committee member).

Subjects/Keywords: Asymmetry; Brightness temperature; Debris disks; Flux density; Infrared excess; Particle collisions; Planetesimals; Planets; Population estimates; Wavelengths; asteroids, astronomy, circumstellar, collisions, debris, disks, dust, dusty, infrared, instrumentation, kuiper, mid, planetary, planets, system, telescopes, thermal

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Moerchen, M. (2008). Location and Origin of Dust in Circumstellar Debris Disks A Mid-Infrared Imaging Study. (Doctoral Dissertation). University of Florida. Retrieved from http://ufdc.ufl.edu/UFE0022653

Chicago Manual of Style (16th Edition):

Moerchen, Margaret. “Location and Origin of Dust in Circumstellar Debris Disks A Mid-Infrared Imaging Study.” 2008. Doctoral Dissertation, University of Florida. Accessed January 19, 2020. http://ufdc.ufl.edu/UFE0022653.

MLA Handbook (7th Edition):

Moerchen, Margaret. “Location and Origin of Dust in Circumstellar Debris Disks A Mid-Infrared Imaging Study.” 2008. Web. 19 Jan 2020.

Vancouver:

Moerchen M. Location and Origin of Dust in Circumstellar Debris Disks A Mid-Infrared Imaging Study. [Internet] [Doctoral dissertation]. University of Florida; 2008. [cited 2020 Jan 19]. Available from: http://ufdc.ufl.edu/UFE0022653.

Council of Science Editors:

Moerchen M. Location and Origin of Dust in Circumstellar Debris Disks A Mid-Infrared Imaging Study. [Doctoral Dissertation]. University of Florida; 2008. Available from: http://ufdc.ufl.edu/UFE0022653

.