In this work techniques for producing large uniform semi-insulating detector-grade CdTe crystals which are free of major structural defects (such as twins, non-uniform dislocation density, and precipitates) have been successfully developed. These p-type CdTe crystals have low carrier concentrations and resistivities of 10 8 -10 9 Ω cm. From such materials photo diodes as X-ray detectors can be designed with low leakage current, low capacitance, high speed, and high quantum efficiency.The use of CdTe for X-ray and gamma detection has been of interest because of its wide bandgap (1.5 eV), which would permit operation of such a device above room temperature, and because of its high atomic number (Z ≈ 50). The photoelectric cross-section is significantly larger than that for GaAs, Ge, and Si. Recently, there has been a great deal of interest in the use of room-temperature semiconductor X-ray detectors for application in medicine, biology, for X-ray non-destructive control and analysis, and in space physics with particular interest in detectors fabricated from CdTe. However, limitations in the charge transport properties and resistivity of the CdTe impose restrictions on its use in X-ray detectors. Furthermore, crystals of CdTe available today grown by the high-pressure Bridgman [1] and traveling heater [2] methods are not uniform in their defect structures and electric and physical properties. This imposes further restrictions on the design of X-ray detectors made from these materials.Nowadays, it is not certain which method of crystal growth is the most appropriate in obtaining large semi-insulating, uniform, and defect-free CdTe crystals. The properties of CdTe crystals used to construct large strip (or pixel) X-ray detectors for digital radiography must be such that the signal is large and does not vary with the pixel position. In the present work our effort is directed towards the growth of large-diameter uniform semi-insulating CdTe crystals required for the fabrication of X-ray imaging detectors. Preliminary results of the detector performance of (p-n) diode, X-ray detectors, fabricated on CdTe crystals are presented.Previously, the method of directed crystallization has been used for the growth of detector-grade CdTe crystals under a controlled pressure of cadmium with defect compensation by introducing Cl in melt [3]. In the present work we have used a variant of this method for the reproducible growth of large-diameter
Presently, research and development of indium-free stable highly transparent conductive (TC) materials is of paramount importance for the blooming world of information display systems and solar energy conversion. Development of devices based on flexible organic substrates further narrows the choice of possible TC materials due to the need for lower deposition and process temperatures. In our work, the structural, electrical, and optical performances of Ga-doped ZnO/Ag/Ga-doped ZnO (GZO/Ag/GZO) multilayered structures deposited on glass substrates by direct current (DC) magnetron sputtering in a pure Ar medium without any purposeful substrate heating have been investigated. The highest figure of merit achieved was 5.15 × 10−2 Ω−1 for the symmetric GZO/Ag/GZO multilayer, featuring GZO and Ag thicknesses of 40 and 10 nm, respectively, while the average optical transmittance was over 81% in the visible range of wavelengths and the resistivity was 2.2 × 10−5 Ω·cm. Additionally, the good durability of the performances of the multilayer structures was demonstrated by their testing in the context of long-term storage (over 500 days) in standard environmental conditions.
The design of a multi-position drum-type assembly (MPDTA) for heating and positioning substrates with the possibility of individually setting and controlling the temperature of each substrate, which is applicable for laboratory-type sputtering setups, is described. The above design provides the possibility of the simultaneous deposition of thin films under identical conditions on several substrates at different temperatures, making it possible to explore the temperature dependences of the films’ morphology, structure, and functional characteristics in one single vacuum deposition cycle. As a case study, the possibility of investigating such dependencies for the magnetron deposition of transparent conducting indium–tin oxide (ITO) thin films was demonstrated using the MPDTA. The investigation results revealed that the functional performances of deposited ITO thin films (resistivity and average transmittance in the visible range) improved with increasing the substrate temperature, reaching values of 1.5 × 10−4 Ω·cm and over 80%, respectively, at 300 °C.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.