Optical and electrical study of CdZnTe surfaces passivated by KOH and NH4F solutions

• Published in: Applied surface science Vol. 389; pp. 1214 - 1219
• Main Authors: Zázvorka, J., Franc, J., Statelov, M., Pekárek, J., Veis, M., Moravec, P., Mašek, K.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.2016
• Subjects: CdTe; Ellipsometry; Leakage current; Passivation; Surface oxide; Leakage current; Surface oxide; CdTe; Passivation; Ellipsometry
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2016.08.103

•Surface of CdZnTe samples was passivated after chemical etching.•KOH and NH4F solutions were used as passivation agents.•Growth of surface oxide after passivation is observed.•Surface oxide thickness was evaluated over time after chemical treatment.•Oxidation of the sample correlates with decreased leakage current. Performance of CdZnTe-based detectors is highly related to surface preparation. Mechanical polishing, chemical etching and passivation are routinely employed for this purpose. However, the relation between these processes and the detector performance in terms of underlying physical phenomena has not been fully explained. The dynamics and properties of CdZnTe surface oxide layers, created by passivation with KOH and NH4F/H2O2 solutions, were studied by optical ellipsometry and X-ray photoelectron spectroscopy (XPS). Thicknesses and growth rates of the surface oxide layers differed for each of the passivation methods. Leakage currents which influence the final spectral resolution of the detector were measured simultaneously with ellipsometry. Results of both optical and electrical investigation showed the same trends in the time evolution and correlated to each other. NH4F/H2O2 passivation showed to be a method which produces the most desirable properties of the surface oxide layer.