Influence of Surface Polishing on the Structural and Electronic Properties of CdZnTe Surfaces

The structural and electronic properties of Cd (x) Zn1-x Te (CZT) surfaces have a significant impact on CZT-based radiation detector performance since they can significantly affect a detector's signal-to-noise ratio. Atomically smooth and defect-free surfaces are desirable for high-performance CZT-based detectors. We studied in this work the effects of chemomechanical polishing on the structural and electronic properties of Cd0.9Zn0.1Te. CZT samples were polished using two different-sized abrasives and then purely chemically to create atomically smooth surfaces. The surface structure and surface electronic properties were characterized by atomic force microscopy, x-ray photoelectron spectroscopy (XPS), and photoluminescence (PL). Surface roughness of about 1 nm was routinely achieved using 1.0-mu m- and 0.05-mu m-sized aluminum abrasives followed by chemical polishing. XPS indicates that the polished surfaces are not stoichiometric and have similar to 1-nm-thick layers of TeO2 on them. PL indicates high-quality CZT at the surface region with full-width at half-maximum of 0.363 meV for the neutral donor exciton peak.