Fast detection of precipitates and oxides on CdZnTe surfaces by spectroscopic ellipsometry

• Published in: Journal of electronic materials Vol. 36; no. 8; pp. 1077 - 1084
• Main Authors: BADANO, G, MILLION, A, CANAVA, B, TRAN-VAN, P, ETCHEBERRY, A
• Format: Conference Proceeding Journal Article
• Language: English
• Published: New York, NY Institute of Electrical and Electronics Engineers 01.08.2007; Springer Nature B.V
• Subjects: Cadmium zinc telluride; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electron, ion, and scanning probe microscopy; Etching; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Molecular, atomic, ion, and chemical beam epitaxy; Physics; Spectrum analysis; Structure of solids and liquids; crystallography; X-rays; Hydroxides; Spectroscopic ellipsometry; Optical models; Zinc tellurides; CdZnTe; Surface chemistry; Precipitates; Tellurium oxides; Thin films; Dielectric function; electroless etchant; ellipsometry; Cadmium tellurides; Molecular beam epitaxy; Oxidation; XPS; X-ray photoelectron spectra
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-007-0176-7

We study the surface chemistry of Cd0.96Zn0.04Te(211)B by X-ray photoelectron spectroscopy and ellipsometry. We obtain first the dielectric functions of amorphous Te and Cd on Cd0.96Zn0.04Te(211)B by in-situ ellipsometry after growing thin films of each material by molecular beam epitaxy. We then study their oxidation in air and show that Cd oxidizes primarily as a hydroxide whereas Te is present as TeO2. In neither case is the oxidation of the films complete, as a substantial amount of either metallic Te or Cd remains even after several days of oxidation. We subsequently exploit an electroless chemical etchant based on Ce to produce Te-rich Cd0.96Zn0.04Te(211)B surfaces which oxidize very little in air. Another etchant containing KCN reduces the amount of alpha-Te substantially. Finally, we construct a tentative optical model for the Cd0.96Zn0.04Te(211)B surface that yields the abundance of amorphous Te on the surface.