Instrumental design for measurement of surface charge on insulating materials

Technical Report · Wed May 01 04:00:00 EDT 1991

OSTI ID:5270896

Beck, S T

The study of electric charge buildup on nonconducting samples requires additional research and development in an attempt to gain knowledge of its behavior. One area affected by charge buildup is the charged particle spectroscopies, specifically, secondary ion mass spectroscopy (SIMS). In SIMS, a sample is bombarded with a primary particle beam that results in secondary ions being displaced from the sample's surface. The secondary ions are focused into the mass spectrometer where they are filtered'' out with respect to their individual atomic masses. When the sample is an insulating material, sample charging eventually occurs due to an imbalance of charged particles leaving the surface. The generated surface charge has severe consequences on the SIMS instrument's ability to perform an analysis. An instrument has been designed and constructed that studies the behavior of charge buildup on insulating materials in an attempt to uncover superior methods that will alleviate its effects in SIMS and other surface analysis techniques. The instrument uses two ion beams; one to apply charge to the sample and the second to determine the voltage located on the surface of the sample. As charge is generated on the sample, a positive cesium ion beam passes parallel to the surface and is deflected by the electrostatic potential on the sample. The cesium beam deflects a specific direction and magnitude, depending on the polarity and magnitude of the sample charge. The displacement of the beam is monitored with the aid of a microchannel plate and photodiode array combination. Experiments performed show that the instrument has a sensitivity of 0.05 volts and an uncertainty drift of 1.5 volts over a 2 hour period. Mylar surface charging data illustrates that the sample voltage is highly dependent on the magnitude and polarity of voltage gradients surrounding the sample. 52 refs., 28 figs., 4 tabs.

• Research Organization: EG and G Idaho, Inc., Idaho Falls, ID (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC07-76ID01570
• OSTI ID: 5270896
• Report Number(s): EGG-CS-9762; ON: DE91018695
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603 -- Materials-- Properties
440800* -- Miscellaneous Instrumentation-- (1990-)
47 OTHER INSTRUMENTATION
CESIUM IONS
CHARGE COLLECTION
CHARGED PARTICLES
DESIGN
ELECTRICAL INSULATION
ESTERS
IONS
MASS SPECTROMETERS
MASS SPECTROSCOPY
MATERIALS
MEASURING INSTRUMENTS
MYLAR
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
PLASTICS
POLYESTERS
POLYMERS
SPECTROMETERS
SPECTROSCOPY
SURFACE PROPERTIES
SYNTHETIC MATERIALS