When 1:30 PM - 3:30 PM Feb 23, 2012
Where GM Room, Lurie Engineering Center
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Examination of the Ion Beam Response of III-V Semiconductor Substrates


Kevin Grossklaus
Thesis Defense

Joanna Millunchick, advisor

 

The unique response of the III-V compound semiconductors to ion irradiation has led to the discovery and development of many new applications for ion beam modification of the III-V materials.  This work encompasses four studies which each examine different ways in which ion beam irradiation affects and may be use to alter common III-V substrate materials. While the motivation and methods of each study are different, they all have the overarching goals of characterizing the response of the III-V materials to ion beam irradiation and attempting to understand the observed results in terms of the fundamental materials processes and properties which control ion-induced change in those compounds. Two of the studies that make up this work examine the use of Ga+ focused ion beam (FIB) irradiation of III-V substrate materials to create nanostructures. The first of those examines the different FIB responses and FIB induced metallic nanodot forming capabilities of GaAs, InP, InAs, and AlAs, and then applies a model to the results in order explain the different response of each material in terms of basic physical properties. The second nanostructure formation study reports on a FIB method for creating unique InAs spike-like nanostructures, termed “nanospikes,” and examines the mechanism by which they are formed, describes the characterization of their structure, and reports results from testing of their electrical properties. The other two studies that make up this work are examinations of how ion beam irradiation may be used to modify III-V substrates for improved lattice-mismatched film growth. The first of these examines how FIB 3-D substrate patterning effects III-V lattice mismatched film growth, and finds that FIB patterning may be used to control film morphology but does not improve the dislocation density of those films. The second substrate modification study examines the effects of broad bream pre-implantation of GaAs substrates with Ar+ or In+ ions on the quality of InGaAs films grown on them. In+ pre-implantation is found to produce no beneficial effect on InGaAs film quality, while Ar+ pre-implantation is found to produce smoother and more relaxed InGaAs films with a higher threading defect density.