Semiconductors

Ab initio calculations of electronic properties and charge transfer in Zn$_{1-x}$Cu$_x$O with wurtzite structure

M. M. Asadov^ab, S. N. Mustafaeva^c, S. S. Guseinova^c, V. F. Lukichev<sup>d

a</sup> Institute of Catalysis and Inorganic Chemistry, Azerbaijan National Academy of Sciences, Baku, Azerbaijan
^b Nagiyev Institute of Catalysis and Inorganic Chemistry, Ministry of Science and Education Republic of Azerbaijan, Baku, Azerbaijan
^c Institute of Physics Azerbaijan Academy of Sciences, Baku, Azerbaijan
^d Valiev Institute of Physics and Technology of Russian Academy of Sciences, Moscow, Russia

Abstract: The results of studying the electronic structure and the influence of the local environment of the copper impurity on the properties and magnetic moment in supercells in Zn$_{1-x}$Cu$_x$O are presented. DFT calculations were carried out in the local electron density (LDA) and generalized gradient approximation (GGA). The band structure of in Zn$_{1-x}$Cu$_x$O was calculated taking into account the correction for spin polarization and the strong electronic interaction. DFT LSDA + $U$ and SGGA + $U$ ($U$ is the Coulomb interaction) calculations made it possible to take into account the contributions of the 3$d$ shells of the Zn and Cu cations to the band spectrum of in Zn$_{1-x}$Cu$_x$O. The introduction of copper into the ZnO lattice leads to a change in the impurity and valence bands of in Zn$_{1-x}$Cu$_x$O. In this case, the bottom of the in Zn$_{1-x}$Cu$_x$O conduction band shifts towards low energies. The total density of electronic states of in Zn$_{1-x}$Cu$_x$O near the Fermi level is mainly determined by the 3$d$ states of Zn and Cu and the 2$p$ state of oxygen. ZnO doped with copper acquires a magnetic moment. The introduction of a vacancy into a supercell in Zn$_{1-x}$Cu$_x$O noticeably changes the local magnetic moment. As the copper concentration in Zn$_{1-x}$Cu$_x$O ($x$ = 0, 0.01, and 0.02) increases, the conductivity of the samples in both constant and alternating current increased, and the activation energy of conduction decreased.

Keywords: ZnO, copper doping, density functional theory, band calculations, electronic structure, localized magnetic moment, defect formation energies, Zn$_{1-x}$Cu$_x$O, charge transfer, parameters of localized states.

Received: 07.01.2021
Revised: 07.01.2021
Accepted: 08.01.2021

DOI: 10.21883/FTT.2022.05.52332.270

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