TY - JOUR
T1 - Development of nanotopography during SIMS characterization of thin films of Ge1-xSnx alloy
AU - Secchi, M.
AU - Demenev, E.
AU - Colaux, J. L.
AU - Giubertoni, D.
AU - Dell'Anna, R.
AU - Iacob, E.
AU - Gwilliam, R. M.
AU - Jeynes, Chris
AU - Bersani, M.
PY - 2015/11/30
Y1 - 2015/11/30
N2 - This work presents a study of application of secondary ion mass spectrometry (SIMS) to measure tin concentration in Ge1-xSnx alloy with x higher than solid solubility ∼1%, i.e. well above the diluted regime where SIMS measurements usually provide the most reliable quantitative results. SIMS analysis was performed on Sn+ ion implanted Ge films, epitaxially deposited on Si, and on chemical vapor deposition deposited Ge0.93Sn0.07 alloy. Three SIMS conditions were investigated, varying primary beam ion species and secondary ion polarity keeping 1 keV impact energy. Best depth profile accuracy, best agreement with the fluences measured by Rutherford backscattering spectrometry, good detection limit (∼1 × 1017 at/cm3) and depth resolution (∼2 nm/decade) are achieved in Cs+/SnCs+ configuration. However, applied sputtering conditions (Cs+ 1 keV, 64° incidence vs. normal) induced an early formation of surface topography on the crater bottom resulting in significant variation of sputtering yield. Atomic force microscopy shows a peculiar topography developed on Ge: for oblique incidence, a topography consisting in a sequence of dots and ripples was observed on the crater bottom. This behavior is unusual for grazing incidence and has been observed to increase with the Cs+ fluence. Rotating sample during sputtering prevents this ripple formation and consequently improves the depth accuracy.
AB - This work presents a study of application of secondary ion mass spectrometry (SIMS) to measure tin concentration in Ge1-xSnx alloy with x higher than solid solubility ∼1%, i.e. well above the diluted regime where SIMS measurements usually provide the most reliable quantitative results. SIMS analysis was performed on Sn+ ion implanted Ge films, epitaxially deposited on Si, and on chemical vapor deposition deposited Ge0.93Sn0.07 alloy. Three SIMS conditions were investigated, varying primary beam ion species and secondary ion polarity keeping 1 keV impact energy. Best depth profile accuracy, best agreement with the fluences measured by Rutherford backscattering spectrometry, good detection limit (∼1 × 1017 at/cm3) and depth resolution (∼2 nm/decade) are achieved in Cs+/SnCs+ configuration. However, applied sputtering conditions (Cs+ 1 keV, 64° incidence vs. normal) induced an early formation of surface topography on the crater bottom resulting in significant variation of sputtering yield. Atomic force microscopy shows a peculiar topography developed on Ge: for oblique incidence, a topography consisting in a sequence of dots and ripples was observed on the crater bottom. This behavior is unusual for grazing incidence and has been observed to increase with the Cs+ fluence. Rotating sample during sputtering prevents this ripple formation and consequently improves the depth accuracy.
KW - GeSn
KW - Nanotopography
KW - Ripple
KW - SIMS protocol
UR - http://www.scopus.com/inward/record.url?scp=84948676982&partnerID=8YFLogxK
U2 - 10.1016/j.apsusc.2015.08.083
DO - 10.1016/j.apsusc.2015.08.083
M3 - Article
AN - SCOPUS:84948676982
SN - 0169-4332
VL - 356
SP - 422
EP - 428
JO - Applied Surface Science
JF - Applied Surface Science
ER -