title: Dynamics of native oxide growth on CdTe and CdZnTe X-ray and gamma-ray detectors.
abstract: 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.
authors.affiliation: Faculty of Mathematics and Physics, Institute of Physics, Charles University in Prague , Prague , Czech Republic.
authors.forename: Jakub
authors.initials: J
authors.lastname: Zázvorka
authors.affiliation: Faculty of Mathematics and Physics, Institute of Physics, Charles University in Prague , Prague , Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Franc
authors.affiliation: Faculty of Mathematics and Physics, Institute of Physics, Charles University in Prague , Prague , Czech Republic.
authors.forename: Lukáš
authors.initials: L
authors.lastname: Beran
authors.affiliation: Faculty of Mathematics and Physics, Institute of Physics, Charles University in Prague , Prague , Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Moravec
authors.affiliation: Faculty of Mathematics and Physics, Institute of Physics, Charles University in Prague , Prague , Czech Republic.
authors.forename: Jakub
authors.initials: J
authors.lastname: Pekárek
authors.affiliation: Faculty of Mathematics and Physics, Institute of Physics, Charles University in Prague , Prague , Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Veis
keywords: 201 Electronics / Semiconductor / TCOs; 212 Surface and interfaces; 40 Optical; CdTe; XPS; ellipsometry; leakage current; magnetic and electronic device materials; oxidation