Time-of-Flight Secondary Ion Mass Spectrometry Studies of Cluster Ion Analysis for Semiconductors and Diffusion of Manganese in Gallium Arsenide at Low Temperatures

Time-of-Flight Secondary Ion Mass Spectrometry Studies of Cluster Ion Analysis for Semiconductors and Diffusion of Manganese in Gallium Arsenide at Low Temperatures
Author: Robyn Goacher
Publisher:
Total Pages: 338
Release: 2010
Genre:
ISBN:

Secondary Ion Mass Spectrometry (SIMS) is an established method for the quantitative analysis of dopants in semiconductors. The quasi-parallel mass acquisition of Time-of-Flight SIMS, along with the development of polyatomic primary ions, have rapidly increased the use of SIMS for analysis of organic and biological specimens. However, the advantages and disadvantages of using cluster primary ions for quantitative analysis of inorganic materials are not clear. The research described in this dissertation investigates the consequences of using polyatomic primary ions for the analysis of inorganic compounds in ToF-SIMS. Furthermore, the diffusion of Mn in GaAs, which is important in Spintronic material applications such as spin injection, is also studied by quantitative ToF-SIMS depth profiling.^In the first portion of this work, it was discovered that primary ion bombardment of pre-sputtered compound semiconductors GaAs and InP for the purpose of spectral analysis resulted in the formation of cluster secondary ions, as well as atomic secondary ions (Chapter 2). In particular, bombardment using a cluster primary ion such as Bi3q+ or C60q+ resulted in higher yields of high-mass cluster secondary ions. These cluster secondary ions did not have bulk stoichiometry, "non-stoichiometric", in contrast to the paradigm of stoichiometric cluster ions generated from salts. This is attributed to the covalent bonding of the compound semiconductors, as well as to preferential sputtering. The utility of high-mass cluster secondary ions in depth profiling is also discussed.^Relative sensitivity factors (RSFs) calculated for ion-implanted Fe and Mn samples in GaAs also exhibit differences based on whether monatomic or polyatomic primary ions are utilized (Chapter 3). These RSFs are important for the quantitative conversion of intensity to concentration. When Bi32+ primary ions are used for analysis instead of Bi+ primary ions, there is a significantly higher proportion of Mn and Fe ions present in the spectra, as referenced to the matrix species. The magnitude of this effect differs depending on the sputtering ion, Cs or C60. The use of C60cluster primary ions for depth profiling of GaAs is also investigated (Chapter 4). In particular, for quantitative depth profiling, parameters such as depth resolution, ion and sputter yields, and relative sensitivity factors are pertinent to profiling thin layered structures quantitatively and quickly.^C60 sputtering is compared to Cs sputtering in all of these aspects. It is found that 10 keV C60+ is advantageous for the analysis of metals (such as Au contacts on Si) but that previously reported roughness problems prohibit successful analysis in Si. For Al delta layers and quantum wells in GaAs, C60q+ sputtering induced very little roughness in the sample, and resulted in high ion yields and excellent signal-to-noise as compared to Cs+ sputtering. However, the depth resolution of C60 is at best equivalent to 1 keV Cs+ and does not extend into the sub 2-nm range. Furthermore, C60 sputtering results in significant carbon implantation. In the second portion of this work, quantitative ToF-SIMS depth profiling was used to evaluate the diffusion of Mn into GaAs. Samples were prepared by Molecular Beam Epitaxy in the department of Physics.^Mn diffusion from MnAs was investigated first, and Mn diffusion from layered epitaxial structures of GaAs / Ga1-xMnxAs / GaAs was investigated second. Diffusion experiments were conducted by annealing portions of the samples in sealed glass ampoules at low temperatures (200-400°C). Different sputtering rates were measured for MnAs and GaAs and the measured depth profiles were corrected for these effects. RSFs measured for Mn ion-implanted standards were used to calibrate the intensity scale. For diffusion from MnAs, thin MnAs layers resulted in no measurable changes except in the surface transient. For thick MnAs layers, it was determined that substantial loss of As occurred at 400°C, resulting in severe sample roughening, which inhibited proper SIMS analysis.^Results for the diffusion of Mn out of a thick buried layer of Ga1-xMnxAs show that annealing induces diffusion of Mn species from the Ga1-xMnxAs layer into the neighboring GaAs with an activation energy of 0.69"0.09 eV. This results in doping of the GaAs layer, which is detrimental to spin injection for Spintronics devices.

Secondary Ion Mass Spectrometry

Secondary Ion Mass Spectrometry
Author: Fred Stevie
Publisher: Momentum Press
Total Pages: 233
Release: 2015-09-15
Genre: Technology & Engineering
ISBN: 1606505890

This book was written to explain a technique that requires an understanding of many details in order to properly obtain and interpret the data obtained. It also will serve as a reference for those who need to provide SIMS data. The book has over 200 figures and the references allow one to trace development of SIMS and understand the many details of the technique.

An Introduction to Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and its Application to Materials Science

An Introduction to Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and its Application to Materials Science
Author: Sarah Fearn
Publisher: Morgan & Claypool Publishers
Total Pages: 67
Release: 2015-10-16
Genre: Technology & Engineering
ISBN: 1681740885

This book highlights the application of Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) for high-resolution surface analysis and characterization of materials. While providing a brief overview of the principles of SIMS, it also provides examples of how dual-beam ToF-SIMS is used to investigate a range of materials systems and properties. Over the years, SIMS instrumentation has dramatically changed since the earliest secondary ion mass spectrometers were first developed. Instruments were once dedicated to either the depth profiling of materials using high-ion-beam currents to analyse near surface to bulk regions of materials (dynamic SIMS), or time-of-flight instruments that produced complex mass spectra of the very outer-most surface of samples, using very low-beam currents (static SIMS). Now, with the development of dual-beam instruments these two very distinct fields now overlap.

BTL Talks and Papers

BTL Talks and Papers
Author: Bell Telephone Laboratories, inc. Technical Information Libraries
Publisher:
Total Pages: 986
Release: 1977
Genre: Physics
ISBN:

Cluster Secondary Ion Mass Spectrometry

Cluster Secondary Ion Mass Spectrometry
Author: Christine M. Mahoney
Publisher: John Wiley & Sons
Total Pages: 325
Release: 2013-04-17
Genre: Science
ISBN: 1118589246

Explores the impact of the latest breakthroughs in cluster SIMS technology Cluster secondary ion mass spectrometry (SIMS) is a high spatial resolution imaging mass spectrometry technique, which can be used to characterize the three-dimensional chemical structure in complex organic and molecular systems. It works by using a cluster ion source to sputter desorb material from a solid sample surface. Prior to the advent of the cluster source, SIMS was severely limited in its ability to characterize soft samples as a result of damage from the atomic source. Molecular samples were essentially destroyed during analysis, limiting the method's sensitivity and precluding compositional depth profiling. The use of new and emerging cluster ion beam technologies has all but eliminated these limitations, enabling researchers to enter into new fields once considered unattainable by the SIMS method. With contributions from leading mass spectrometry researchers around the world, Cluster Secondary Ion Mass Spectrometry: Principles and Applications describes the latest breakthroughs in instrumentation, and addresses best practices in cluster SIMS analysis. It serves as a compendium of knowledge on organic and polymeric surface and in-depth characterization using cluster ion beams. It covers topics ranging from the fundamentals and theory of cluster SIMS, to the important chemistries behind the success of the technique, as well as the wide-ranging applications of the technology. Examples of subjects covered include: Cluster SIMS theory and modeling Cluster ion source types and performance expectations Cluster ion beams for surface analysis experiments Molecular depth profiling and 3-D analysis with cluster ion beams Specialty applications ranging from biological samples analysis to semiconductors/metals analysis Future challenges and prospects for cluster SIMS This book is intended to benefit any scientist, ranging from beginning to advanced in level, with plenty of figures to help better understand complex concepts and processes. In addition, each chapter ends with a detailed reference set to the primary literature, facilitating further research into individual topics where desired. Cluster Secondary Ion Mass Spectrometry: Principles and Applications is a must-have read for any researcher in the surface analysis and/or imaging mass spectrometry fields.