Electronic, Band Offset, and Thermoelectric Properties of ZnO/GaN Heterostructure from First-Principles Study
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https://doi.org/10.1007/s11664-020-08341-1 Ó 2020 The Minerals, Metals & Materials Society
Electronic, Band Offset, and Thermoelectric Properties of ZnO/ GaN Heterostructure from First-Principles Study N. KOUAYDI1 and M. ZEMZEMI1,2 1.—Laboratory of Physics of Materials and Nanomaterials Applied to Environment, Faculty of Sciences of Gabes, University of Gabes, Erriadh City, Zrig, 6072 Gabe`s, Tunisia. 2.—e-mail: [email protected]
Structural, electronic, band offset, and thermoelectric properties of zinc oxide (ZnO), gallium nitride (GaN), and the ZnO/GaN heterostructure have been investigated. First, first-principles calculations are used to study the electronic structure of ZnO, GaN, and ZnO/GaN. The band offsets at the ZnO/ GaN(0001) heterointerface are then calculated, revealing type II band alignment. The thermoelectric properties of ZnO, GaN, and the ZnO/GaN heterostructure are also studied using Boltzmann transport theory. Moreover, the Seebeck coefficient, electrical conductivity, electrical thermal conductivity, and figure of merit of ZnO, GaN, and ZnO/GaN are calculated. The ZnO/GaN heterostructure exhibits substantially improved thermoelectric properties, suggesting its potential use in thermoelectric devices. Key words: ZnO/GaN heterostructure, density functional theory (DFT), electronic properties, thermoelectric properties, band offsets
INTRODUCTION Semiconductor heterostructures have attracted great attention and have been widely studied due to their unique properties and application potential.1 The ZnO/GaN heterostructure has exceptional modern applications due to its suitable bandgap corresponding to the wavelength range of visible light and its excellent transport capacity, which helps to improve electron transfer, resulting in high sensitivity and quick response properties.2–5 In recent decades, several publications documenting potential applications of the ZnO/GaN heterostructure have appeared, including as a photocatalysts for hydrogen generation by water splitting,6–12 in optoelectronic devices such as next-generation ultraviolet light-emitting diodes (UV-LEDs),13–17 and for their thermoelectric properties. In fact, growth of ZnO/ GaN heterostructures has been achieved using methods such as the sol–gel technique,18 pulsed
(Received January 6, 2020; accepted July 16, 2020)
laser deposition (PLD),19–21 sputtering,22,23 metalorganic chemical vapor deposition (MOCVD),24,25 electrochemical deposition (ECD),26,27 molecular beam epitaxy (MBE),28 etc. Furthermore, this heterostructure is characterized by potential advantages including a simple fabrication process, the ability to design efficient hybrid structures, the tunability of the emission wavelength, and the possibility of using ZnO semiconductors, which are cheap, stable, and exhibit a large exciton binding energy (60 meV).29 ZnO and GaN share many properties. Indeed, these semiconductors with a wide bandgap of around 3.30 eV to 3.4 eV29,30 both crystallize in the same hexagonal structure31 and have almost the same lattice parameters. Many
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