Donor DBH excitons and magnetism of Mn doped ZnO

• Published in: Journal of physics. Conference series 2019-11, Vol.1389 (1), p.12078
• Main Authors: Sokolov, V I, Gruzdev, N B, Vazhenin, V A, Fokin, A V, Korolev, A V, Menshenin, V V, Surikov, V T, Yemelchenko, G A
• Format: Article
• Language: English
• Subjects: Absorption spectra; Conduction bands; Curie temperature; D lines; Excitons; Line spectra; Magnetic measurement; Magnetic permeability; Magnetism; Manganese ions; Optical communication; Oxygen ions; Physics; Single crystals; Temperature dependence; Zinc oxide; Zinc oxides
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/1389/1/012078

In this paper the results of the study of optical absorption, photo-EPR signals and magnetic measurements of hydrothermal single crystals of zinc oxide doped with manganese were presented. Several lines were detected in optical absorption spectra at the temperature of 4.2 K and 77.3 K for σ- and π- polarizations of light in a 1.72-2.3 eV spectral range. These lines are attributed to a donor exciton [(d5 + h)e] that emerges as a result of the Coulomb binding of a free s electron and a hole, which is localized on p-d hybridized states. Properties of these lines are significantly different from the properties of lines of donor and acceptor excitons in II-VI:3d compounds. In EPR-spectra of Zn1-xMnxO crystals the intensity of allowed and forbidden EPR-signals of Mn2+ (d5)-ions does not change under the illumination while the intensity of EPR-signals of unintentional Fe3+ (d5)-ions decreases by 70 %. The value of the magnetic susceptibility of Zn1-xMnxO (x = 0.0009) is in linear dependence with temperature, which agrees with the Curie equation. Temperature dependence of the inverse value of the Mn2+ magnetic susceptibility indicates that the exchange interaction in ZnO:Mn crystals is absent. New experimental results allow us to assume that investigated Zn1-xMnxO (x = 0.0009) samples are semiconductors in the forbidden gap of which the donor level of d5/d4 does not exist. The hybridization of d5 states of Mn2+ and p states of the nearest four oxygen ions O2- leads to pushing out the antibonding DBH-states (d5 + p) into the forbidden gap. The transitions of electrons from DBH-states to the conduction band provide a broad band of the impurity absorption in ZnO:Mn. Below this band we observed a, b, c and d lines, which are called dbh-donor excitons [(d5+h)e].