Defense Date

2011

Document Type

Thesis

Degree Name

Master of Science

Department

Engineering

First Advisor

Supriyo Bandyopadhyay

Abstract

Electronic noise is an area of fundamental importance that reveals information about the system that transport or optical measurements cannot. The present work focuses on recent advances made in the area of noise in nanodevices. This area is attracting increasing attention because noise in nanostructures is qualitatively and quantitatively different from that in bulk systems. Chapter 1 discusses different kinds of noise in nanostructures with a focus on 1/f noise. Monte-Carlo simulation is used to find velocity as a function of time to calculate velocity autocorrelation function and noise spectral density. The spectrum has 1/f^2 dependence which is universal irrespective of electric field and temperature which implies that it is a fundamental effect. In analogy with electronic noise spin noise is studied in Chapter 2. Fluctuation in spin polarization of carriers in semiconductor structures gives rise to spin noise. Spin transport is simulated using Monte-Carlo simulator in presence of D’yakonov-Perel’ spin relaxation mechanism. The symmetry breaking electric field which induces Rashba field is changed in magnitude and direction. Random spatial variation of the Rashba field causes little difference in temporal spin relaxation characteristics in the regime of high-field transport. Spin does not relax monotonically with position but a non-monotonic chaotic trend is observed when Rashba field is varied randomly in magnitude or direction. Chapter 3 discusses electrochemical self-assembly technique employed to fabricate highly ordered nanowires. This nanofabrication technique can be used to grow highly ordered and size controlled nanowires and quantum dots of different materials. Cadmium sulfide nanowires are grown using this method and their infrared photodetectivity is studied. We observe twice as much increase in current under illumination at any given bias.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

August 2011

Included in

Engineering Commons

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