Updates of Iowa State University

S. Dumpala, S. Broderick, A. J. Peralta and K. Rajan

Mar – 11 - 2013

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

• Interface shown from reaction of O and Al. Identify Al2O3 as bulk phase of gas-solid reaction

• Use of AP results for experimental inputs into ReaxFF simulations

Summary of Previous Al oxidation results

Diffusion Profiles - APT

Environmental Chamber- APT

• Heater stage preheated to 500 C (sample T-300 C)

• Pressure – 7x 10 -5 torr for 5 min

• APT – Laser run at 1 nj

• Different oxygen species are detected as observed earlier

Present - Al oxidation results

Study of InterfacesDiffusion Profiles - APT

Al

O

Al- Iso surface 95.23%

• Oxidation forming – AlO phase compared to stoichiometric Al2O3 phase observed earlier

• Different oxide species observed

Bulk Al2O3 phase Bulk Al phase

Al

O

• XPS, HRTEM also reported formation of limiting thickness Al-deficient phase than Al2O3 at <573 K [1]

• The observed formation of stoichiometric Al2O3 phase at higher temperature is consistent with ref [1] for temperature 773 K

• The thickness shown to increase with increasing temperature [1] also consistent with APT results.

[1] Jeurgesn L.P.H., et. al., J. App. Phys. 2002, 92, 1649

Bulk Al phase

AlO

573 K 723 K

Effect of Temperature

Future

• More experiments as function of temperature and pressures

• Study of oxidation mechanism

• Testing the Si tips from Maryland