The PHI 5700 ESCA System

The PHI ESCA (XPS) System is used to collect data from the surfaces of solid samples under ultra-high vacuum conditions. Incident photon beams are either Mg K-alpha (1253.6 eV) or Al K- alpha monochromatic x-rays (1486.6 eV). Photoelectrons from the first 30-100 angstroms of the solid surface are energy analyzed and compared to known values. Chemical assignments are based upon the binding energy of the photoelectron peak. For example, a silicon 2p photoelectron peak at 99.1 eV is assigned to Si⁰, whereas a peak at 103.7 eV is assigned to SiO₂.

The PHI ESCA is also equipped with an argon ion gun which enables the user to etch away surface layers in a controlled manner. This feature can be used to remove suspected surface contamination and to depth profile through successive layers in a solid sample.

XPS operating modes:

• Survey scan
• High resolution (detailed scan)
• Angle resolved
• Depth profile

Samples we have analyzed by XPS.....

• Polymer coated gold wires
• Self assembled monolayers on yttrium-barium-copper oxide (YBCO) films and gold surfaces
• Molybdenum sulfur oxidation state(s) on alumina-based catalysts
• Heteroatom adsorbed species on zeolites
• Thin metal oxide (i.e., Ta2O5) films on bare, oxidized, or nitrided silicon surfaces
• Super acid salts in polymer matrix
• Iridium films on oxidized silicon and strontium barium titanate (SrBaTiO3) surfaces
• AlN/GaN on sapphire surfaces
• Organometallic precursors (i.e., TiN, TaN ,GaSb)
• Magnese oxidation state(s) in La0.67Ca0.33MnO3, La1-xSixMn1 yO3 samples
• CVD vs. thermally grown oxide on silicon surfaces
• Nitrogen and/or chlorine containing hydrocarbons on graphite electrode surfaces
• AlGaAs/GaAs/AlGaAs on GaAs surfaces
• InAlP/InGaP/GaAs/AlGaAs on GaAs surfaces
• Adhesives on silicon surfaces
• Polyimide films
• TiO2/W/WN on silicon surfaces
• TiCN and TiCN/W/Wn on silicon surfaces
• Gold and sulfur nanoparticles on superconductor film
• GaN particles on conductive glass
• Coated hydroxyapatite materials
• Colored residues on filter paper
• Impurities in silicon wafers
• Calcium metaphosphate polymer on alumina and tungsten oxide materials

The PHI 7200 TOF/SALI System

The PHI ToFSIMS SYSTEM is also used to collect data from the surfaces of solid samples under ultra-high vacuum conditions. Incident cesium ions (Cs⁺) at 8 KeV strike the sample surface. Secondary ions (positive and negative) ejected from the surface are detected via a time-of-flight mechanism. The secondary ions generally emerge from the first 10-20 angstroms of the solid surface. Chemical assignments are based upon the molecular weight of the intact, fragmented and/or clustered ions. For example, an ions at 27.97 (Si⁺), 13.98 (Si⁺²), 55.95 (Si₂⁺), 83.92 (Si₃⁺), and 160.88 (CsSi⁺) are indicative of a clean silicon surface. In contrast, ions at 43.97 (SiO⁺), 71.94 (Si₂O⁺), 88.94 (Si₂O₂⁺), 148.90 (CsO⁺), 160.88 (CsSi⁺) and 176.8 (CsSiO⁺) are indicative of an oxidized silicon surface (i.e., SiO_x).

Similar to the PHI ESCA, the PHI ToFSIMS can also be used to profile through successive layers in a solid sample.

ToFSIMS(not pictured) operating modes

• Survey scan
• Depth profile

Samples we have analyzed by ToFSIMS....

• Thin metal oxide (i.e., Ta2O5) films on bare, oxidized, or nitrided silicon surfaces
• super acid salts in polymer matrix
• Al/TiNC on oxidized silicon surfaces
• Iridium films on oxidized silicon and strontium barium titanate (SrBaTiO3) surfaces
• Organometallic precursors (i.e., TiN)

The majority of the students and faculty who request XPS and/or ToFSIMS service are associated with the STC. However, students and faculty from within the University community are welcomed to submit samples for analysis. Each sample must be accompanied by a Sample Form (see below) and brought directly to the laboratory in Welch Hall 3.218.

Additional inquires can be directed to ... via electronic mail (?), phone (471-5846), or fax (471-9495).

If you would like some work done on the XPS, please fill out this Sample Form, and bring it when you come in.