Experimental Work - Atom Probe Tomography

At Iowa State University

S. Dumpala, S. Broderick, A. Bryden, K. Kaluskar and K. Rajan

• Growth behavior of ultrathin silica layers by laser detonation hyperthermal atomic beam source (1-15 eV) of atomic and molecular oxygen

• Study of occurrence of pure Si, SiOx,and SiO2 and growth directions of oxidized (black arrows) and silica layers (red arrows)

Study of Growth of Different Oxidized Layers : APT

U. Khaliov, et al. J. Phys. Chem.C, 115, 2011

ReaxFF Simulations

Atom Probe Tomography(Model System – Oxidation of Aluminum)

• Oxidation of Aluminum at 450 C, 2.5 x 10-3 Torr for 10 min.

• Chemical composition and atomic structure from 3D image of elemental mapping with atomic-scale resolution

Bulk Al2O3 phase Bulk Al phase

Al

O

Study of Interfaces

Possible Link

Diffusion Profiles - APT Mass and Charge distributions – ReaxFF Simulations

U. Khaliov, et al. J. Phys. Chem.C, 115, 2011

Al

O

Effect of Growth Temperature

U. Khaliov, et al. J. Phys. Chem.C, 116, 2012

Environmental Chamber- APT

• Different Temperatures up to 800 C

• Different pressures ranges (low 10 -5 torr)

• Different gas phase chemistries

• Different time scales

• Different sample orientations

Possible Experimental Studies - Oxidation

ReaxFF SimulationsAPT

Mass Spectra - APT

Ion Evaporation Map

Diffusion ProfilesStudy of Interfaces

Use APT to study compound formation, bond strengths (crystal structure changes), evaporation physics/ionic dissociation, and charge states of bonded atoms.

Experimental Studies at Maryland

• 10 coupons each with 36 Si (100) micro tips (6x6 rows) were sent to University of Maryland to obtain the samples of known fluence and energy spectrum to evaluate the change in surface morphology

Typical Silicon Coupon