Abstract

The majority of image detectors to date have used silicon photodiode arrays for light capture and image formation. However, as imaging is performed in increasingly harsh environments, conventional silicon arrays begin to reach their physical device limitations and fail. Harsh imaging conditions include short wavelengths, high temperatures, and/or high radiation conditions. To aid future detector development, the theoretical energy-conversion efficiency of wide-bandgap semiconductor materials, which are long known for their favorable properties in harsh environments, has been studied. It has been hypothesized, but not shown until now, that wide bandgap semiconductors have better energy-conversion efficiencies at higher temperatures than conventional semiconductor materials. The basic element of the photodiode, the p-n junction, is investigated using fundamental physical equations including the short-circuit current, open-circuit voltage, and energy-conversion efficiency, as a function of temperature and material. The results of several wide-bandgap materials (i.e. GaP, SiC, and GaN) are compared to silicon. The limitations of current silicon detector technologies (CCDs) and the potential of these wide-bandgap semiconductors as imaging and non-imaging devices (e.g. solar cells and alpha-voltaic batteries) are presented. Experimental results showing the normalized to Si energy-conversion efficiency as a function of temperature for Si, InGaP, and SiC substantiate the theoretical conclusions that wide bandgap semiconductors offer better efficiencies at higher temperatures than narrow bandgap semiconductors.

Library of Congress Subject Headings

Wide gap semiconductors--Optical properties; Wide gap semiconductors--Thermal properties; Optical detectors--Materials; Imaging systems--Materials

Publication Date

2007

Document Type

Thesis

Student Type

Graduate

Degree Name

Imaging Science (MS)

Department, Program, or Center

Chester F. Carlson Center for Imaging Science (COS)

Advisor

Ryne Raffaelle

Advisor/Committee Member

Stefi Baum

Advisor/Committee Member

Mehdi Araghi

Comments

Physical copy available from RIT's Wallace Library at QC611.8.W53 M37 2007

Campus

RIT – Main Campus

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