Growth, structure, and electronic properties of molybdenum/silicon thin films by Molecular beam epitaxy (MBE).

Persistent Link:
http://hdl.handle.net/10150/184846
Title:
Growth, structure, and electronic properties of molybdenum/silicon thin films by Molecular beam epitaxy (MBE).
Author:
Shapiro, Arye.
Issue Date:
1989
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Mo-Si thin films have proven applications in semiconductor devices and x-ray optics. Since their performance in these applications is extremely sensitive to interface roughness, it is important to understand the nucleation and growth mechanisms which affect the microscopic interface structure. Investigations of the initial stages of interface formation in the Mo-Si system were carried out by depositing fractional-monolayer Mo films onto Si(100)-(2x1) and Si(111)-(7x7) surfaces using Molecular Beam Epitaxy (MBE) with feedbackcontrolled electron-beam evaporation, and by characterizing these ultra-thin Mo films using in situ Reflection High-Energy Electron Diffraction (RHEED), LowEnergy Electron Diffraction (LEED), Auger Electron Spectroscopy (AES), and xray Photoelectron Spectroscopy (XPS). Continuous growth of multiple Mo coverages on a single Si wafer was accomplished with a technique developed for these experiments, involving a moveable substrate shutter. The coverages were corrected for the deposition profile (due to growth chamber geometry) with ex situ Rutherford Backscattering Spectroscopy (RBS) data and computer modelling. The growth mode was determined using Auger intensity measurements. In order to correct for the time dependence of the Auger intensities due to trace surface contamination and instrumental drift, a technique was developed which used Auger measurements on bulk Si and Mo to further normalize the intensity data for the fractional-monolayer coverages of Mo. The AES results in this dissertation show that for relatively slow Mo deposition (i.e. rates of approximately 0.05 Angstroms per second) onto either (100) or (111) Si substrates maintained at low temperatures (i.e. 100 °C), the first atomic monolayer of Mo is deposited in a non-layer-by-layer fashion, implying interdiffusion and/or agglomeration of the Mo overlayer. The LEED and RHEED results on similar samples show that the Mo layer is non-crystalline, i.e. there is no long-range periodicity. In addition, the deposition of Mo destroys the periodicity of the underlying Si atoms. For these deposition conditions, both the growth mode and the lack of crystallinity are independent of Si surface crystal structure.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Thin films.; Molybdenum alloys.; Silicon alloys.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Physics; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Falco, Charles M.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleGrowth, structure, and electronic properties of molybdenum/silicon thin films by Molecular beam epitaxy (MBE).en_US
dc.creatorShapiro, Arye.en_US
dc.contributor.authorShapiro, Arye.en_US
dc.date.issued1989en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractMo-Si thin films have proven applications in semiconductor devices and x-ray optics. Since their performance in these applications is extremely sensitive to interface roughness, it is important to understand the nucleation and growth mechanisms which affect the microscopic interface structure. Investigations of the initial stages of interface formation in the Mo-Si system were carried out by depositing fractional-monolayer Mo films onto Si(100)-(2x1) and Si(111)-(7x7) surfaces using Molecular Beam Epitaxy (MBE) with feedbackcontrolled electron-beam evaporation, and by characterizing these ultra-thin Mo films using in situ Reflection High-Energy Electron Diffraction (RHEED), LowEnergy Electron Diffraction (LEED), Auger Electron Spectroscopy (AES), and xray Photoelectron Spectroscopy (XPS). Continuous growth of multiple Mo coverages on a single Si wafer was accomplished with a technique developed for these experiments, involving a moveable substrate shutter. The coverages were corrected for the deposition profile (due to growth chamber geometry) with ex situ Rutherford Backscattering Spectroscopy (RBS) data and computer modelling. The growth mode was determined using Auger intensity measurements. In order to correct for the time dependence of the Auger intensities due to trace surface contamination and instrumental drift, a technique was developed which used Auger measurements on bulk Si and Mo to further normalize the intensity data for the fractional-monolayer coverages of Mo. The AES results in this dissertation show that for relatively slow Mo deposition (i.e. rates of approximately 0.05 Angstroms per second) onto either (100) or (111) Si substrates maintained at low temperatures (i.e. 100 °C), the first atomic monolayer of Mo is deposited in a non-layer-by-layer fashion, implying interdiffusion and/or agglomeration of the Mo overlayer. The LEED and RHEED results on similar samples show that the Mo layer is non-crystalline, i.e. there is no long-range periodicity. In addition, the deposition of Mo destroys the periodicity of the underlying Si atoms. For these deposition conditions, both the growth mode and the lack of crystallinity are independent of Si surface crystal structure.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectThin films.en_US
dc.subjectMolybdenum alloys.en_US
dc.subjectSilicon alloys.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePhysicsen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorFalco, Charles M.en_US
dc.identifier.proquest9005728en_US
dc.identifier.oclc703280427en_US
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.