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Laser Doped Layer in CdTe Diode Detectors Revealed by Synchrotron XPS
Author(s)
Date Issued
November 1, 2018
Type
Conference Paper
Abstract
The X-ray photoelectron spectroscopy (XPS) with 650 eV synchrotron radiation was applied to study the modified surface layers in the CdTe diode-type X/γ-ray detectors fabricated by the laser-induced doping techniques. Semi-insulating (111)-oriented p-like CdTe single crystals, pre-coated with an In dopant film, were irradiated by nanosecond pulses of a YAG:Nd laser (λ = 1064 nm). The activation of the In/CdTe interface and doping were carried out by laser irradiation of the metalized samples from the In side or through the semiconductor which was transparent for such wavelength. In the first case, laser-induced doping was attributed to the generation of laser-stimulated stress and shock waves which incorporated In atoms into the CdTe surface region. In the second case, it was possible to directly affect the In/CdTe interface because laser radiation was strongly absorbed by a thin layer of the deposited In dopant film and the CdTe was dissolved in molten In. The distribution of In and Cd atoms with the depth and atomic bonding in the In/CdTe interface were analyzed based on the high resolution In 3d and Cd 3d peaks in the XPS spectra of the formed In/CdTe diode structures subjected to Ar-ion sputtering. The stoichiometry and transformation of electronic structure in the modified CdTe layer were analyzed. Rectification properties of the created In/CdTe/Au diodes were due to the formation of an In enriched submicron layer as result of laser-induced solid-phase or liquid-phase doping that depended on irradiation of the In/CdTe structure from the metalized or semiconductor side, respectively. The created In/CdTe/Au diodes have been promising for X/γ-ray detector application.
Citation
2018 IEEE Nuclear Science Symposium and Medical Imaging Conference NSS Mic 2018 Proceedings, 2018