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Depth-compositional analyses -angle-resolved x-ray photoelectron spectroscopy- of degradations on etched mercury cadmium telluride.

Kompositionelle Tiefenprofilanalyse -winkelaufgelöste Röntgen-Photoelektron-Spektroskopie- von Degradationen auf geätztem Quecksilber-Cadmium-Tellurid
: Seelmann-Eggebert, M.; Richter, H.J.

Journal of vacuum science and technology A. Vacuum, surfaces and films 6 (1988), No.4, pp.2699-2709 : Abb.,Tab.,Lit.
ISSN: 0734-2101
Journal Article
Fraunhofer IAF ()
Ar-Ionenbeschuß; Ätzrückstand; degradation; Eigenoxid; Röntgen-Photoelektronen-Spektroskopie(winkelaufgelöst); Sputtern; Tiefenprofil; Voltametrie

The effects of etching on the surface composition of mercury cadmium telluride (MCT) have been reexamined with the objective of differentiating between residues of etching and degradations of the underlying MCT samples. To determine the depth-compositional profiles of such layered structures on etched MCT, angle-resolved x-ray photoemission (ARXPS) as an analytical tool was used. In this approach a model of photoemission from a planar MCT bulk sample covered with two homogeneous overlayers (representing the residue and the degradation) comprised the basis of the computer-aided ARXPS analysis. The thicknesses and the compositions of the two overlayers were the parameters of a curve fitting to data points processed from the sets of raw signature data which were taken by XPS at different photoelectron escape angles. It was found that dry etching by sputtering (3-keV Ar+ ions at a dose of 2x10 E16 cm E-2 and 300K) yields an almost homogeneous depletion of the HgTe component in the degraded surface region which extends to a depth of more than 50 A. In addition, elemental Te occurs as an artifact of sputtering in the outer layer. Wet etching (Br2 in methanol) was observed to form a residue composed of elemental Te and native oxide phases of MCT (HgTe2O5 and CdTe2O5) in which the ratio Hg/Cd was generally larger than in the bulk. However, the underlying MCT substrate was not found to be depleted in Cd. (IAF)