Study the Influence of High Pressure on the Optical and Electronic Properties of Composite ZnO Using (DFT-GGA)

Ahmed Shihatha,Abdulhadi Ghaleb,Rafea Munef

doi:10.33899/rjs.2021.169974

Abstract

In this article, the lattice constants, band structure and optical characteristics of ZnO wurtzite structure under various pressures were studied using the generalized gradient approximation (GGA) method. This method is based on the functional density (DFT) Theory, according to the first principle. The results show that as the pressure increases and the band gap increases, the lattice constants (a and c) decrease. As the pressure increases, the minimum conduction band will move to a higher energy level, and the maximum valence band will move to a lower energy level, thereby increasing the energy band difference. As the pressure increases, the shape of the optical parameter curve remains almost unchanged, and all peaks move to higher energies. The state density, dielectric function, reflectance and absorption coefficient are also calculated. The overview of the spectrum and optical properties is discussed, including the imaginary part of the dielectric function, reflectance and absorption coefficient of wurtzite-type ZnO under environmental conditions. The optical constants indicate that the phase of ZnO wurtzite structure is transparent. We noticed that our measurements are comparable to those observed in the literature.

Highlights

ZnO has been widely used because it can be used in many optical devices, such as electrochemistry, optoelectronics, water splitting (Li and Zhang, 2010), ultraviolet detectors (Liu et al, 2010), lasers (Kalusniak et al, 2009), optically transparent electrodes (Ellmer, 2012), transparent thin film transistors and Metal diode-insulation-semiconductor (Özgür et al, 2005)
It is worth noting that at room temperature, a transition phase of ZnO wurtzite structure to rock salt ZnO is observed about 9 GPa. (Pellicer-Porres et al, 2011) the stable stage of rock salt is as high as 56.6 GPa (Desgreniers, 1998)
Determine the energy gap and lattice constant of each equilibrium geometry under pressure. (Table 1) summarizes the results of structural parameters, volume and band gap energy, In the same table, his work results were compared with the previous results (Decremps et al, 2003; Bornstein et al, 1979; Zhao et al, 2014; John and Padmavathi, 2016), we noticed that a good agreement were noticed with their results except for the energy gap

Summary

Introduction

ZnO has been widely used because it can be used in many optical devices, such as electrochemistry, optoelectronics, water splitting (Li and Zhang, 2010), ultraviolet detectors (Liu et al, 2010), lasers (Kalusniak et al, 2009), optically transparent electrodes (Ellmer, 2012), transparent thin film transistors and Metal diode-insulation-semiconductor (Özgür et al, 2005). It is not possible to avoid the original point defects in the ZnO growth process, the high-pressure properties are calculated because the pure ZnO material does not correspond to the current funding situation. There are a great number of experimental and theoretical publications on the characteristics of zinc oxide composite structures having vesicle impurities and pure of ZnO wurtzite structure high - pressure behavior (Wang et al, 2014; McCluskey and Jokela, 2009; Sun et al, 2013), our understanding of the structure, electrical and optical properties of ZnO will still be considered defects such as oxygen vacancies and interstitial zinc are limited and incomplete under high pressure. The DFT/GGA method was first used to examine the effect of variable pressure treatment on the structure of ZnO, and other optical properties were calculated

Methods

Results

Conclusion