Storage Conditions for High-Accuracy Composition Standards of AlGaAs
Kristine A. Bertness, Alexana Roshko, S. E. Asher, Craig L. Perkins
AlGaAs epitaxial films were stored under different environmental conditions and the resulting surface oxidation and contamination variations measured using several analytical techniques. Auger depth profiles confirmed that oxidation and carbon contamination had been confined to within approximately 10 nm of the surface for all specimens stored in controlled environments for over three years. We also performed an atomic force microscopy (AFM) study on a multilayer structure measuring the height of the oxides formed in air. Surface contamination was examined in more detail with time-of-flight secondary ion mass spectrometry (TOF-SIMS). Surface oxides appeared to change over time, and could be altered by sputtering. Sputtering was particularly effective in removing hydrocarbon contamination. We observed a tendency for oxidized surfaces to resist hydrocarbon accumulation. The randomness of some hydrocarbon peak intensities suggests that specimens could have been contaminated incidentally in handling. This work was performed in support of a program at NIST to provide standard reference materials for analyzing the Al mole fraction of AlGaAs films. Based on these results, the reference films for x < 0.5 should remain stable for at least three years if stored in either nitrogen or vacuum environments, with allowance for periodic handling in air.
composition standards, storage conditions, surface contamination, time-of-flight secondary ion mass spectroscopy
, Roshko, A.
, Asher, S.
and Perkins, C.
Storage Conditions for High-Accuracy Composition Standards of AlGaAs, Journal of Vacuum Science and Technology B, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=31834
(Accessed December 3, 2023)