Study on the effects of Ga-2N high co-doping and preferred orientation on the stability, bandgap and absorption spectrum of ZnO

2017 ◽  
Vol 31 (14) ◽  
pp. 1750107
Author(s):  
Qing-Yu Hou ◽  
Wen-Cai Li ◽  
Ling-Feng Qu ◽  
Chun-Wang Zhao
Keyword(s):  
Absorption Spectrum ◽  
Absorption Spectra ◽  
Theoretical Calculations ◽  
Co Doping ◽  
Unit Cells ◽  
Neighboring Site ◽  
Doped Zno ◽  
The Stability ◽  
Formation Energies ◽  
Co Doped

Currently, the stability and visible light properties of Ga-2N co-doped ZnO systems have been studied extensively by experimental analysis and theoretical calculations. However, previous theoretical calculations arbitrarily assigned Ga- and 2N-doped sites in ZnO. In addition, the most stable and possible doping orientations of doped systems have not been fully and systematically considered. Therefore, in this paper, the electron structure and absorption spectra of the unit cells of doped and pure systems were calculated by first-principles plane-wave ultrasoft pseudopotential with the GGA[Formula: see text]U method. Calculations were performed for pure ZnO, Ga-2N supercells heavily co-doped with Zn[Formula: see text]Ga[Formula: see text]O[Formula: see text]N[Formula: see text] ([Formula: see text], [Formula: see text]) under different co-doping orientations and conditions, and the Zn[Formula: see text]GaN2O[Formula: see text] interstitial model. The results indicated that under different orientations and constant Ga-2N co-doping concentrations, the systems co-doped with Ga-N atoms vertically oriented to the [Formula: see text]-axis and with another N atom located in the nearest-neighboring site exhibited higher stability over the others, thus lowering formation energy and facilitating doping. Moreover, Ga-interstitial- and 2N-co-doped ZnO systems easily formed chemical compounds. Increasing co-doping concentration while the co-doping method remained constant decreased doped system volume and lowered formation energies. Meantime, co-doped systems were more stable and doping was facilitated. The bandgap was also narrower and red shifting of the absorption spectrum was more significant. These results agreed with previously reported experimental results. In addition, the absorption spectra of Ga-interstitial- and 2N-co-doped ZnO both blue shifted in the UV region compared with that of the pure ZnO system.

Transport mechanisms in Co-doped ZnO (ZCO) and H-irradiated ZCO polycrystalline thin films

2021 ◽  
Vol 23 (3) ◽  
pp. 2368-2376
Author(s):  
A. Di Trolio ◽  
A. Amore Bonapasta ◽  
C. Barone ◽  
A. Leo ◽  
G. Carapella ◽  
...  
Keyword(s):  
Thin Films ◽  
Opposite Effect ◽  
Transport Mechanisms ◽  
Co Doping ◽  
Polycrystalline Thin Films ◽  
Doped Zno ◽  
Co Doped

Co doping increases the ZnO resistivity (ρ) at high T (HT), whereas it has an opposite effect at low T (LT). H balances the Co effects by neutralizing the ρ increase at HT and strengthening its decrease at LT.

Effects on the magnetic and optical properties of Co-doped ZnO at different electronic states

2017 ◽  
Vol 31 (31) ◽  
pp. 1750247
Author(s):  
Qingyu Huo ◽  
Zhenchao Xu ◽  
Linfeng Qu
Keyword(s):  
Absorption Spectrum ◽  
Spin Polarization ◽  
Electron Spin ◽  
Magnetic Moments ◽  
The State ◽  
Band Gaps ◽  
Electron Spin Polarization ◽  
Approximation Formula ◽  
Doped Zno ◽  
Co Doped

Both blue and red shifts in the absorption spectrum of Co-doped ZnO have been reported at a similar concentration range of doped Co. Moreover, the sources of magnetism of Co-doped ZnO are controversial. To solve these problems, the geometry optimization and energy of different Co-doped ZnO systems were calculated at the states of electron spin polarization and nonspin polarization by adopting plane-wave ultra-soft pseudopotential technology based on density function theory. At the state of electron nonspin polarization, the total energies increased as the concentration of Co-doped increased. The doped systems also became unstable. The formation energies increased and doping became difficult. Furthermore, the band gaps widened and the absorption spectrum exhibited a blue shift. The band gaps were corrected by local-density approximation + [Formula: see text] at the state of electron spin polarization. The magnetic moments of the doped systems weakened as the concentration of doped Co increased. The magnetic moments were derived from the coupling effects of [Formula: see text]–[Formula: see text]. The band gaps narrowed and the absorption spectrum exhibited a red shift. The inconsistencies of the band gaps and absorption spectrum at the states of electron spin polarization and nonspin polarization were first discovered in this research, and the sources of Co-doped ZnO magnetism were also reinterpreted.

Effect of cobalt doping on microstructures and dielectric properties of ZnO

2019 ◽  
Vol 97 (3) ◽  
pp. 227-232 ◽  
Author(s):  
Ye Zhao ◽  
Fan Tong ◽  
Mao Hua Wang
Keyword(s):  
Zno Nanoparticles ◽  
Sol Gel ◽  
Hexagonal Wurtzite Structure ◽  
Sem Analysis ◽  
Co Doping ◽  
In Doping ◽  
Zno Powders ◽  
Doped Zno ◽  
Zno Crystal ◽  
Co Doped

Pure and cobalt-doped ZnO nanoparticles (2.5, 5, 7.5, and 10 atom % Co) are synthesized by sol–gel method. The as-synthesized nanoparticles are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FE-SEM) analysis. The nanoparticles of 0, 2.5, and 5 atom % Co-doped ZnO exhibited hexagonal wurtzite structure and have no other phases. Moreover, the (101) diffraction peaks position of Co-doped ZnO shift toward a smaller value of diffraction angle compared with pure ZnO powders. The results confirm that Co ions were well incorporated into ZnO crystal lattice. Simultaneously, Co doping also inhibited the growth of particles, and the crystallite size decreased from 43.11 nm to 36.63 nm with the increase in doping concentration from 0 to 10 atom %. The values of the optical band gap of all Co-doped ZnO nanoparticles gradually decreased from 3.09 eV to 2.66 eV with increasing Co content. Particular, the dielectric constant of all Co-doped ZnO ceramics gradually increased from 1.62 × 103 to 20.52 × 103, and the dielectric loss decreased from 2.36 to 1.28 when Co content increased from 0 to 10 atom %.

Phenyl Substitution Effects on Triplet–Triplet Absorption Spectra: I. Study of 1,3,6,8-Tetraphenylpyrene

1975 ◽  
Vol 53 (21) ◽  
pp. 3269-3275 ◽  
Author(s):  
C. Rullière ◽  
E. C. Colson ◽  
P. C. Roberge
Keyword(s):  
Absorption Spectrum ◽  
Triplet State ◽  
Absorption Spectra ◽  
Rate Constant ◽  
Theoretical Calculations ◽  
Vibrational Structure ◽  
Substitution Effects ◽  
Quenching Rate ◽  
Diffusion Controlled ◽  
Quenching Rate Constant

The triplet–triplet (T–T) absorption spectrum of 1,3,6,8-tetraphenylpyrene (TPP) was measured from 400 to 620 nm. The data obtained are compared with theoretical calculations using the Ruedenberg–Scherr FEMO model. A planar triplet state is evidenced by fine vibrational structure. The T–T quenching rate constant measured (1.3 ± 0.1 × 109 M−1 s−1) is 20% of the expected diffusion-controlled value.

Structural and Electrical Properties of (Cu, Co) Co-Doped ZnO Thin Film

2013 ◽  
Vol 774-776 ◽  
pp. 964-967
Author(s):  
Ping Cao ◽  
Yue Bai
Keyword(s):  
Electrical Properties ◽  
Sol Gel ◽  
Hall Effect Measurement ◽  
X Ray Diffraction ◽  
Zno Film ◽  
Co Doping ◽  
Structural And Electrical Properties ◽  
Doped Zno ◽  
Cu Ions ◽  
Co Doped

Successful synthesis of Cu, Co co-doped ZnO film is obtained by sol-gel method. The structural and electrical properties of the sample were investigated. X-ray diffraction spectroscopy analyses indicate that the Co and Cu co-doping can not disturb the structure of ZnO. No additional peaks are observed in the Zn0.99Co0.01CuxO and Cu+ and Co2+ substitute for Zn2+ without changing the wurtzite structure. By Hall-effect measurement p-type conductivity was observed for the Cu co-doped film. XPS result confirmed Cu ions are univalent in the films.

DEFECT FORMATION AND MAGNETIC PROPERTIES OF Co-DOPED ZnO NANOWIRES

NANO ◽  
2013 ◽  
Vol 08 (02) ◽  
pp. 1350021 ◽  
Author(s):  
LI BIN SHI ◽  
GUO QUAN QI ◽  
YING FEI
Keyword(s):  
Magnetic Properties ◽  
Density Functional ◽  
Defect Formation ◽  
Density Functional Method ◽  
Zno Nanowires ◽  
Generalized Gradient ◽  
Surface Sites ◽  
Doped Zno ◽  
Formation Energies ◽  
Co Doped

The defect formation energies and magnetic properties in Co -doped ZnO nanowires (NWs) are studied using the first-principle density functional method within the generalized gradient approximation (GGA) and GGA + U schemes. It is found that Co impurity has lower formation energies in the surface sites, indicating that Co impurity occupies preferably surface sites of NWs. Ferromagnetic (FM) and antiferromagnetic (AFM) coupling are investigated by GGA and GGA + U methods. The results show that the AFM coupling in energy is lower than the FM coupling, which indicates that AFM coupling is more stable. The magnetic properties can be mediated by the vacancies [ VO(B) and VZn(B) ] and interstitials [ IZn(oct) ]. The stability of the FM and AFM can be explained by the Co 3d energy level coupling.

The Structural, Electrical, Magnetic Properties of (Cu, Co) Co-Doped ZnO Thin Film

2014 ◽  
Vol 556-562 ◽  
pp. 429-432
Author(s):  
Ping Cao ◽  
Yue Bai ◽  
Zhi Qu
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Sol Gel ◽  
Hall Effect Measurement ◽  
Ferromagnetic Semiconductors ◽  
Zno Thin Film ◽  
Zno Film ◽  
Co Doping ◽  
Doped Zno ◽  
Co Doped

Successful synthesis of room-temperature ferromagnetic semiconductors, (Cu, Co) co-doped ZnO film is obtained by sol-gel method. It is found that the essential ingredient in achieving room-temperature ferromagnetism is Cu co-doping. By Hall-effect measurement ap-type conductivity was observed for the Cu co-doped films, which induced the room-temperature ferromagnetism.

Effect of Co doping on the physical properties of Co-doped ZnO nanoparticles

2017 ◽  
Vol 28 (8) ◽  
pp. 5953-5961 ◽  
Author(s):  
Zohra N. Kayani ◽  
Iqra Shah ◽  
Saira Riaz ◽  
Shahzad Naseem
Keyword(s):  
Physical Properties ◽  
Zno Nanoparticles ◽  
Co Doping ◽  
Doped Zno ◽  
Co Doped

scholarly journals Physical Investigations of (Co, Mn) Co-Doped ZnO Nanocrystalline Films

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1507
Author(s):  
Bechir Yahmadi ◽  
Olfa Kamoun ◽  
Badriyah Alhalaili ◽  
Safia Alleg ◽  
Ruxandra Vidu ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Magnetic Measurements ◽  
Texture Coefficient ◽  
Room Temperature Ferromagnetism ◽  
Band Gap Energy ◽  
X Ray ◽  
Co Doping ◽  
Glass Substrates ◽  
Doped Zno ◽  
Co Doped

Undoped as well as (Co, Mn) co-doped Zinc oxides have been effectively developed on glass substrates, taking advantage of the spray pyrolysis procedure. The X-ray diffraction XRD as well as X-ray photoelectron spectroscopy (XPS) measurements have recognized a pure hexagonal wurtzite form of ZnO, and no other collateral phases such as MnO2 or CoO2 have been observed as a result of doping. The calculated values of the texture coefficient (TC) were between 0.15 and 5.14, indicating a dominant orientation along the (002) plane. The crystallite size (D) varies with the (Co, Mn) contents. The dislocation density (δ) as well as the residual microstrains increased after Co and Mn doping. Furthermore, the surface morphology of the films has been affected significantly by the Co and Mn incorporation, as shown by the scanning electron microscopy (SEM) investigation. The study of the optical properties exhibits a red shift of the band gap energy (Eg) with the (Co, Mn) co-doping. The magnetic measurements have shown that the undoped and (Co, Mn) co-doped ZnO thin films displayed room-temperature ferromagnetism (RTFM).

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