MOLECULAR BEAM EPITAXY OF SEMICONDUCTOR HETEROSTRUCTURES FOR SPINTRONICS

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" MOLECULAR BEAM EPITAXY OF SEMICONDUCTOR HETEROSTRUCTURES FOR SPINTRONICS "

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	150086
Doc. No	:	ET21878
Main Entry	:	Keh-Chiang Ku
Title Proper	:	MOLECULAR BEAM EPITAXY OF SEMICONDUCTOR HETEROSTRUCTURES FOR SPINTRONICS
Note	:	This document is digital این مدرک بصورت الکترونیکی می باشد
Abstract	:	In this dissertation, we use molecular beam epitaxy to engineer a variety of materials ofrelevance to the emerging research field known as semiconductor spintronics. The broadaim of this research is to establish a fundamental framework that exploits electronicspin states in semiconductors for the manipulation, transfer, detection and storage ofinformation. We explore two complementary approaches towards the implementation ofsemiconductor spintronics:1. We use materials known as diluted magnetic semiconductors wherein itinerantcharge carriers are exchange coupled with magnetic ions incorporated into thesemiconductor lattice. This results in a spin polarization of both the carriers aswell as the magnetic moments themselves.2. Alternatively, we use optical techniques to introduce spin polarization into theFermi sea in a conventional (non-magnetic) semiconductor, and then subsequentlymonitor the coherent dynamic evolution of this spin polarization. This enablesthe study of electron spin coherence in semiconductors for applications where thequantum mechanical phase of a wave function is important.We begin this dissertation by discussing the underlying basis for diluted magnetic semiconductors.We then follow this with a discussion of experimental studies of the crystalgrowth and physical properties of a ب‍canonicalپ case: Ga1-xMnxAs. We first review howthe structural, electrical and magnetic properties of as-grown Ga1-xMnxAs epilayers aresubstantially altered by post-growth annealing. We then highlight an important advanceachieved during this dissertation, namely the identification of growth and annealing parametersthat result in samples with consistently reproducible Curie temperatures up to150 K. We also discuss experiments that show how the the proximity of a free surfaceinfluences the maximum attainable Curie temperature in a given sample architecture.In particular, we show that a GaAs capping layer as thin as a few monolayers can significantlysuppress the enhancement of the Curie temperature associated with annealing.We next consider heterostructures that integrate Ga1-xMnxAs with other materials,including the fabrication of Ga1-xMnxAs on ZnSe(001) using a recrystallized GaAs,..tested for theQ1 PC1 bus cardBoth these projects mere sofixare des elopment efforts tonards contributing to dlfferentaspects of Roboucs and lZ1echatronics projects m the Controls and Roboucs Group..
Subject	:	Electericl tess
	:	برق
electronic file name	:	TL45069.pdf
Title and statement of responsibility and	:	MOLECULAR BEAM EPITAXY OF SEMICONDUCTOR HETEROSTRUCTURES FOR SPINTRONICS [Thesis]