Dynamics of native oxide growth on CdTe and CdZnTe X-ray and gamma-ray detectors

• Published in: Science and technology of advanced materials Vol. 17; no. 1; pp. 792 - 798
• Main Authors: Zázvorka, Jakub, Franc, Jan, Beran, Lukáš, Moravec, Pavel, Pekárek, Jakub, Veis, Martin
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 01-01-2016; Taylor & Francis Ltd; Taylor & Francis Group
• Subjects: 201 Electronics / Semiconductor / TCOs; 212 Surface and interfaces; 40 Optical; Bromine; Cadmium zinc tellurides; CdTe; Chemical etching; Chemical treatment; ellipsometry; Gamma ray detectors; Leakage current; magnetic and electronic device materials; Optical, Magnetic and Electronic Device Materials; oxidation; Photoelectrons; Spectroellipsometry; Surface layers; Surface preparation; Tellurium; XPS; 40 Optical; ellipsometry; 212 Surface and interfaces; oxidation; 201 Electronics / Semiconductor / TCOs; leakage current; XPS; CdTe; magnetic and electronic device materials
• ISSN: 1468-6996; 1878-5514
• DOI: 10.1080/14686996.2016.1250105

We studied the growth of the surface oxide layer on four different CdTe and CdZnTe X-ray and gamma-ray detector-grade samples using spectroscopic ellipsometry. We observed gradual oxidization of CdTe and CdZnTe after chemical etching in bromine solutions. From X-ray photoelectron spectroscopy measurements, we found that the oxide consists only of oxygen bound to tellurium. We applied a refined theoretical model of the surface layer to evaluate the spectroscopic ellipsometry measurements. In this way we studied the dynamics and growth rate of the oxide layer within a month after chemical etching of the samples. We observed two phases in the evolution of the oxide layer on all studied samples. A rapid growth was visible within five days after the chemical treatment followed by semi-saturation and a decrease in the growth rate after the first week. After one month all the samples showed an oxide layer about 3 nm thick. The oxide thickness was correlated with leakage current degradation with time after surface preparation.