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Articles 1 - 6 of 6
Full-Text Articles in Electrical and Computer Engineering
Low-Frequency Noise In N-Gan With High Electron Mobility, M. E. Levinshtein, S. L. Rumyantsev, D. C. Look, R. J. Molnar, M. Asif Khan, Grigory Simin, V. Adivarahan, M. S. Shur
Low-Frequency Noise In N-Gan With High Electron Mobility, M. E. Levinshtein, S. L. Rumyantsev, D. C. Look, R. J. Molnar, M. Asif Khan, Grigory Simin, V. Adivarahan, M. S. Shur
Faculty Publications
We report on the results of measurements of low frequency noise in n-type gallium nitride (GaN) grown on sapphire with 300 K electron mobility of 790 cm2/V s. The noise spectra have the form of 1/f noise with a Hooge parameter α of approximately 5×10−2. This value of α is two orders of magnitude smaller than that observed before in n-GaN. The obtained results show that the level of flicker noise in GaN, just like that in GaAs and Si, strongly depends on the structural perfection of the material (the amplitude of the 1/f …
Piezoelectric Doping In Alingan/Gan Heterostructures, M. Asif Khan, J. W. Yang, Grigory Simin, R. Gaska, M. S. Shur, A. D. Bykovski
Piezoelectric Doping In Alingan/Gan Heterostructures, M. Asif Khan, J. W. Yang, Grigory Simin, R. Gaska, M. S. Shur, A. D. Bykovski
Faculty Publications
We report on the piezoelectricdoping and two-dimensional (2D) electron mobility in AlInGaN/GaN heterostructures grown on 6H–SiC substrates. The contribution of piezoelectricdoping to the sheet electron density was determined using an In-controlled built-in strain-modulation technique. Our results demonstrate that in strained AlGaN/GaN heterostructures, the piezoelectric field generates at least 50% of the 2D electrons. The strain modulation changes the potential distribution at the heterointerface, which, in turn, strongly affects the 2D electron mobility, especially at cryogenic temperatures. The obtained results demonstrate the potential of strain engineering and piezoelectricdoping for GaN-based electronics.
A Translation And Rotation Independent Fingerprint Identification Approach, Hongyu Wang
A Translation And Rotation Independent Fingerprint Identification Approach, Hongyu Wang
Graduate Theses - Electrical and Computer Engineering
This thesis describes a new approach for fingerprint identification that will be shift and rotation independent. Detailed descriptions of directional filtering, foreground and background segmentation, feature extraction, and matching based on structural correlation are the main topics of this thesis. The fingerprint identification system consists of image preprocessing, feature extraction, and matching which run on a PC platform. The preprocessing step includes histogram equalization, block-based directional filtering, thinning, and adaptive thresholding to enhance the original images for successful feature extraction. The features extracted will be stored in the database for matching. The matching algorithm presented is a modification and improvement …
Guest Editorial: Special Section On Acousto-Optic Devices And Optical Information Processing: Research And Developments, Partha P. Banerjee, Ting-Chung Poon
Guest Editorial: Special Section On Acousto-Optic Devices And Optical Information Processing: Research And Developments, Partha P. Banerjee, Ting-Chung Poon
Electrical and Computer Engineering Faculty Publications
This guest editorial provides an overview of the topical area and an introduction to the articles featured in the special section.
Laser Beam Profile Deformation Effect During Bragg Acousto-Optic Interaction: A Non-Paraxial Approximation, Ray S. Huang, Chen-Wen Tarn, Partha P. Banerjee, Doungchin Cao
Laser Beam Profile Deformation Effect During Bragg Acousto-Optic Interaction: A Non-Paraxial Approximation, Ray S. Huang, Chen-Wen Tarn, Partha P. Banerjee, Doungchin Cao
Electrical and Computer Engineering Faculty Publications
It is commonly known that the spatial profiles of the diffracted light beams during Bragg acousto-optic interaction are distorted due to the Bragg angle selection mechanism. All the conventional studies on this effect use the paraxial approximation. But this approximation should be amended when the incident angle of the light is large enough that the diffracted light waves do not propagate closely along the optic axis of the acousto-optic diffraction system. By using a spatial Fourier transform approach, we rigorously study the light beam profile deformation effect of the diffracted light during the Bragg acousto-optic interaction beyond the paraxial approximation. …
Examination Of Beam Propagation In Misaligned Holographic Gratings And Comparison With The Acousto-Optic Transfer Function Model For Profiled Beams, Monish Ranjan Chatterjee, David D. Reagan
Examination Of Beam Propagation In Misaligned Holographic Gratings And Comparison With The Acousto-Optic Transfer Function Model For Profiled Beams, Monish Ranjan Chatterjee, David D. Reagan
Electrical and Computer Engineering Faculty Publications
A transfer function formalism developed earlier for the propagation of profiled optical beams through acousto-optic Bragg cells is revisited and applied to a thick holographic grating. The results based on the holographic coupled wave model and the acousto-optic multiple scattering model are shown to be compatible, and equivalent parameters such as the Q and grating strength are defined for the two systems. Results for a Gaussian spatial profile are numerically computed and compared. For the holographic grating, a profiled beam may be interpreted as an angular misalignment or Bragg-angle mismatch problem. The case of Bragg-wavelength mismatch is also investigated for …