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Multispectral plasmon enhanced quantum dots in a well infrared photodetectors

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Please use this identifier to cite or link to this item: http://hdl.handle.net/1928/12113

Multispectral plasmon enhanced quantum dots in a well infrared photodetectors

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dc.contributor.author Shenoi, Rajeev V
dc.date.accessioned 2011-02-09T20:54:22Z
dc.date.available 2011-02-09T20:54:22Z
dc.date.issued 2011-02-09
dc.date.submitted December 2010
dc.identifier.uri http://hdl.handle.net/1928/12113
dc.description.abstract Infrared detectors in 3-5 μm and 8-12 μm regions are extensively used for applications in remote sensing, target detection and medical diagnostics. Detectors using intersubband transitions in the quantum dots in a well (DWELL) system for infrared detection have gained prominence recently, owing to their ability to detect normally incident light, bicolor detection and use of mature III-V technology. In this dissertation, two aspects of DWELL detectors that make them suitable for third generation infrared systems are discussed: 1) High temperature operation, 2) Multispectral detection. There are two parts to this dissertation. In the first part, an alternate structure with an improved operating temperature and thicker active region is presented. Traditionally, DWELL detectors use InAs quantum dots embedded in In0.15Ga0.85As wells with GaAs barriers. Intersubband transitions in the conduction band of this system result in infrared detection. InAs quantum dots are grown using self assembly on a GaAs substrate for this system. The strain of the quantum dots and the In0.15Ga0.85As well limits the thickness of the active region. An improved design that minimizes the strain in growth of DWELL active region is discussed. By minimizing the amount of In0.15Ga0.85As in the quantum well, a lower strain per DWELL active region stack is achieved. This design consists of InAs dots in In0.15Ga0.85As/GaAs wells, forming dots-in-a-double-well (DDWELL) is presented. Optimization using PL and AFM is discussed. Detectors fabricated using DDWELL design show an operating temperature of 140 K and a background limited performance at 77 K. A peak detectivity of 6.7×1010 cm.Hz/W was observed for a wavelength of 8.7 μm. In the second part of this dissertation, multispectral and polarization detectors using DWELL absorbers are discussed. Integration of a subwavelength metallic pattern with the detector results in coupling of surface plasmons excited at the metal- semiconductor interface with DWELL active regions. Simulations indicate the presence of several modes of absorption, which can be tuned by changing the pitch of the pattern. Enhancement of absorption is predicted for the detector. Experimental demonstration show spectral tuning in MWIR and LWIR regions and a peak absorption enhancement of 4.9×. By breaking the symmetry of the fabricated pattern, we can extract a polarization dependent response, as shown from device measurements. The technique used is detector agnostic, simple and can easily be transferred to focal plane arrays (FPA). Integrating plasmonic structures on detectors using low noise DDWELL active regions can provide a higher operating temperature and high absorption. The origin of resonant peaks in multispectral DWELL detectors is examined. Use of surface patterns that selectively excite different types of modes, with absorbers of different thicknesses, show the presence of enhancement mechanisms in these devices. A 2.2× enhancement is measured from waveguide modes and 4.9× enhancement is observed from plasmon modes. Finally, a pathway of integration with FPA and integration with other infrared technologies is discussed. en_US
dc.language.iso en_US en_US
dc.subject infrared detectors en_US
dc.subject focal plane arrays en_US
dc.subject quantum dots en_US
dc.subject plasmons en_US
dc.subject multi-spectral detection en_US
dc.subject quantum dots in a well en_US
dc.subject.lcsh Infrared detectors.
dc.subject.lcsh Quantum dots.
dc.subject.lcsh Plasmons (Physics)
dc.title Multispectral plasmon enhanced quantum dots in a well infrared photodetectors en_US
dc.type Dissertation en_US
dc.description.degree Engineering en_US
dc.description.level Doctoral en_US
dc.description.department University of New Mexico. Dept. of Electrical and Computer Engineering en_US
dc.description.advisor Krishna, Sanjay
dc.description.committee-member Brueck, Steven R. J
dc.description.committee-member Prasad, Sudhakar
dc.description.committee-member Hayat, Majeed


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