Specific Features of Spectrally Resolved Thermoluminescence in UV-Irradiated Aluminum Nitride Microcrystals
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CAL MATERIALS
Specific Features of Spectrally Resolved Thermoluminescence in UV-Irradiated Aluminum Nitride Microcrystals D. M. Spiridonova, D. V. Chaikina, N. A. Martemyanova, A. S. Vokhmintseva, and I. A. Weinsteina, b, * a NANOTECH
b
Center, Ural Federal University, Yekaterinburg, 620002 Russia Institute of Metallurgy, Ural Branch, Russian Academy of Sciences, Yekaterinburg, 620016 Russia *e-mail: [email protected] Received February 11, 2020; revised February 11, 2020; accepted March 28, 2020
Abstract—The mechanisms of photo- and thermoluminescence processes in cation-deficient submicron AlN crystals after UV excitation are studied. The observed emission spectra represent a superposition of bands peaking at 3.0 and 2.5 eV. These spectral features are related to electronic transitions with participation of ON impurity centers and oxygen–vacancy centers of the VAl–ON type. According to a quantitative analysis within the general-order kinetics formalism, charge carrier trapping centers based on nitrogen vacancies VN have an activation energy of 0.45 eV and are responsible for the formation of a thermally activated peak at a temperature of 345 K. Keywords: AlN, photoluminescence, thermoluminescence, activation energy, oxygen-related center, vacancy DOI: 10.1134/S0030400X20090210
INTRODUCTION At present, much attention is paid to the creation of micro- and nanostructures based on III-nitrides with different morphological properties, as well as to the study of their properties as applied to solving various practical problems of opto- and nanoelectronics. Aluminum nitride takes an important place among these materials due to its wide band gap (about 6.2 eV), chemical stability, high thermal conductivity, etc. [1– 7]. There exist examples of AlN application for fabricating light emitting diodes, surface acoustic wave devices, substrates for electronic elements, and materials for detection of ionizing radiation of various natures [8–14]. In addition, AlN micro- and nanostructures are used for development of compact devices based on UV and visible microlasers [8, 15–18]. The technological methods of AlN synthesis have significant restrictions. Most of these methods (chloride-assisted growth, carbon nanotube-confined reaction, arc discharge, silica-assisted catalytic growth, and vapor–liquid–solid growth) are characterized by low efficiency, expensive precursors, and a high concentration of impurities in the final products [19–25]. In this connection, the search for methods of AlN synthesis with the possibility of formation of crystal structures with a prescribed geometry and desired spectral characteristics is a topical problem of modern optical materials science. In the present work, we study the luminescent properties of submicron cation-
deficient AlN crystals in the form of hexagonal prisms synthesized by an original method. EXPERIMENTAL In this work, we study the properties of microcrystalline AlN powder synthesized using a special setup by gas-phase synthesis with simultaneous treatment of liquid aluminum wi
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