Ion yields and erosion rates for Si{sub 1-x}Ge{sub x}(0<=x<=1) ultralow energy O{sub 2}{sup +} secondary ion mass spectrometry in the energy range of 0.25-1 keV

Journal Article · Mon Jun 01 04:00:00 EDT 2009 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3139279· OSTI ID:21352237

Morris, R J. H.; Dowsett, M G ^[1]

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1. Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL (United Kingdom)

We report the SIMS parameters required for the quantitative analysis of Si{sub 1-x}Ge{sub x} across the range of 0<=x<=1 when using low energy O{sub 2}{sup +} primary ions at normal incidence. These include the silicon and germanium secondary ion yield [i.e., the measured ion signal (ions/s)] and erosion rate [i.e., the speed at which the material sputters (nm/min)] as a function of x. We show that the ratio R{sub x} of erosion rates, Si{sub 1-x}Ge{sub x}/Si, at a given x is almost independent of beam energy, implying that the properties of the altered layer are dominated by the interaction of oxygen with silicon. R{sub x} shows an exponential dependence on x. Unsurprisingly, the silicon and germanium secondary ion yields are found to depart somewhat from proportionality to (1-x) and x, respectively, although an approximate linear relationship could be used for quantification across around 30% of the range of x (i.e., a reference material containing Ge fraction x would give reasonably accurate quantification across the range of +-0.15x). Direct comparison of the useful (ion) yields [i.e., the ratio of ion yield to the total number of atoms sputtered for a particular species (ions/atom)] and the sputter yields [i.e., the total number of atoms sputtered per incident primary ion (atoms/ions)] reveals a moderate matrix effect where the former decrease monotonically with increasing x except at the lowest beam energy investigated (250 eV). Here, the useful yield of Ge is found to be invariant with x. At 250 eV, the germanium ion and sputter yields are proportional to x for all x.

• OSTI ID: 21352237
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 11 Vol. 105; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALLOYS
APPROXIMATIONS
CALCULATION METHODS
CHARGED PARTICLES
CHEMICAL ANALYSIS
ELEMENTS
GERMANIUM
GERMANIUM ALLOYS
GERMANIUM IONS
ION MICROPROBE ANALYSIS
IONS
MASS SPECTRA
MASS SPECTROSCOPY
METALS
MICROANALYSIS
NONDESTRUCTIVE ANALYSIS
NONMETALS
OXYGEN
SEMIMETALS
SILICON
SILICON ALLOYS
SPECTRA
SPECTROSCOPY
SPUTTERING