updates of iowa state university

Download Updates of Iowa State University

Post on 07-Feb-2016

26 views

Category:

Documents

0 download

Embed Size (px)

DESCRIPTION

Updates of Iowa State University. S. Dumpala , S. Broderick and K. Rajan May – 14 - 2013. Summary of Previous Results. Atom probe experimentation Atomic scale measurement of gas-solid reactions of Al and Oxygen and Si and O systems Compound formation Study of Interfacial chemistry - PowerPoint PPT Presentation

TRANSCRIPT

PowerPoint Presentation

Updates of Iowa State University S. Dumpala, S. Broderick and K. Rajan

May 14 - 2013 Summary of Previous Results Atom probe experimentationAtomic scale measurement of gas-solid reactions of Al and Oxygen and Si and O systems Compound formation Study of Interfacial chemistryEnvironmental chamber for in-situ gas reactions Unique features and capabilities

Collaborations: Maryland Sample prepared by Maryland by reacting Si microtips; analysis of samples by ISU Van Duin group Use of atom probe results for experimental inputs into ReaxFF simulationsProgressAtom probe experimentation

Refinements in Environmental chamber set up for in-situ gas reactions

- Oxidation studies of Al using new set up of E-cell

Study of Si tips from Maryland using APT

E-Cell : Modifications/ImprovementsCooling water lines were installed for turbo pump

Burst disk valve is added (prevent any accidental excess pressure build up of the chamber)

Mass flow controller and pressure regulator is added with flow sensor bypassed with pressure sensor to be able to regulate the flow with desired pressure set point very close to the main reaction cell (small chamber)

Prssures as low as 0.1 milli torr can be regulated with the new setup.

Digital reader/regulator of the pressure is included.

Base pressures is as low as 1 x 10-5 torr

4 tip holder was used.All the four tips were cleaned using laser atom probe runs prior to oxidation reaction to remove the contamination and native oxide layerOxidation was done using the E-cell at 450 C (sample temperature), 20 milli torr for 30 minLaser atom probe ( 0.5 nj) was used to study the oxidized needles.Al Oxidation with New set up of E-cell

Study of InterfacesDiffusion Profiles - APTAl- Iso surface 82.39%

Si Tips from Maryland :Sample 2 (Anode Voltage: 250 V, 50 monolayers of Argon exposure) Tip 1Laser Atom probe was employedLaser energy 1 nj

Sample 2 (Anode Voltage: 250 V, 50 monolayers of Argon exposure) Tip 2

Sample 2 (Anode Voltage: 250 V, 50 monolayers of Argon exposure) Tip 7No SEM doneWas able to collect 2.8 million dataThick oxide layer at the very tip and higher Argon content observed here

Bare Si tipNo SEM doneLower oxide content

Mass Spectra Comparison

More background noiseDetection of ArgonHigher hydrogen content

Base Si tipAfter exposed to Ar beamFutureMore experiments as function of temperature and pressures

Testing the Si tips from Maryland using FIMCheck other condition tips (Different beam currents)Different deposition thickness of monolayersFIM studies

Recommended

View more >