Fermi-level band filling and band-gap renormalization in Ga-doped ZnO

This research paper proposes the usage of a simple thermal treatment method to synthesis the pure and Eu3+ doped ZnO/Zn2SiO4 based composites which undergo calcination process at different temperatures. The effect of calcination temperatures on the structural, morphological, and optical properties of ZnO/Zn2SiO4 based composites have been studied. The XRD analysis shows the existence of two major phases which are ZnO and Zn2SiO4 crystals and supported by the finding in the FT-IR. The FESEM micrograph further confirms the existence of both ZnO and Zn2SiO4 crystal phases, with progress in the calcination temperature around 700–800 °C which affects the existence of the necking-like shape particle. Absorption humps discovered through UV-Vis spectroscopy revealed that at the higher calcination temperature effects for higher absorption intensity while absorption bands can be seen at below 400 nm with dropping of absorption bands at 370–375 nm. Two types of band gap can be seen from the energy band gap analysis which occurs from ZnO crystal and Zn2SiO4 crystal progress. It is also discovered that for Eu3+ doped ZnO/Zn2SiO4 composites, the Zn2SiO4 crystal (5.11–4.71 eV) has a higher band gap compared to the ZnO crystal (3.271–4.07 eV). While, for the photoluminescence study, excited at 400 nm, the emission spectra of Eu3+ doped ZnO/Zn2SiO4 revealed higher emission intensity compared to pure ZnO/Zn2SiO4 with higher calcination temperature exhibit higher emission intensity at 615 nm with 700 °C being the optimum temperature. The emission spectra also show that the calcination temperature contributed to enhancing the emission intensity.

Download Full-text

Tuning Fermi Level and Band Gap in Li 4 Ti 5 O 12 by Doping and Vacancy for Ultrafast Li + Insertion/Extraction

Journal of the American Ceramic Society ◽

10.1111/jace.17948 ◽

2021 ◽

Author(s):

Zhenya Wang ◽

Hao Guo ◽

De Ning ◽

Xiaobai Ma ◽

Lirong Zheng ◽

...

Keyword(s):

Fermi Level ◽

Band Gap

Download Full-text

First-Principles Study on the Conductive Properties of P-Doped ZnO

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.79-82.1253 ◽

2009 ◽

Vol 79-82 ◽

pp. 1253-1256 ◽

Cited By ~ 1

Author(s):

Li Guan ◽

Qiang Li ◽

Xu Li ◽

Jian Xin Guo ◽

Bo Geng ◽

...

Keyword(s):

Fermi Level ◽

Valence Band ◽

Density Functional ◽

Lattice Structure ◽

Mulliken Charge ◽

Total Density ◽

Type Conductivity ◽

Doped Zno ◽

P Type ◽

Conductive Properties

In the present paper, the lattice structure, band structure and density of state of pure and P-doped ZnO are calculated by first-principle method based on density functional theory. By analyzing the Mulliken charge overlap population and bond length, it is found that the bond of P-Zn is longer and stronger than O-Zn bond for PO-ZnO. But for PZn-ZnO, the O-P bond becomes shorter and more powerful than O-Zn bond. Also, weak O-O bonds are formed in this case. Our results show that the final total energy of PO-ZnO is lower than PZn-ZnO. The lattice structure of PO-ZnO is more stability than PZn-ZnO. For PO-ZnO, The Fermi level moves into the valence band, which expresses that the holes appear on the top of valence band and thus the PO-ZnO exhibits p-type conductivity. For PZn-ZnO, the Fermi level moves up to the conductor band and the total density of states shifts to the lower energy region, thus PZn-ZnO shows the n-type conductivity.

Download Full-text

Wide Band Gap Al and In Co-doped ZnO Films for Near-Infrared Plasmonic Application

Plasmonics ◽

10.1007/s11468-021-01434-5 ◽

2021 ◽

Author(s):

Soumya Kannoth ◽

Packia Selvam Irulappan ◽

Sandip Dhara ◽

Sankara Narayanan Potty

Keyword(s):

Band Gap ◽

Near Infrared ◽

Wide Band ◽

Zno Films ◽

Wide Band Gap ◽

Doped Zno ◽

Co Doped

Download Full-text

Band gap engineering and enhanced photoluminescence of Mg doped ZnO nanoparticles synthesized by wet chemical route

Journal of Luminescence ◽

10.1016/j.jlumin.2014.12.016 ◽

2015 ◽

Vol 161 ◽

pp. 275-280 ◽

Cited By ~ 63

Author(s):

Mohd. Arshad ◽

Mohd. Meenhaz Ansari ◽

Arham S. Ahmed ◽

Pushpendra Tripathi ◽

S.S.Z. Ashraf ◽

...

Keyword(s):

Band Gap ◽

Zno Nanoparticles ◽

Chemical Route ◽

Band Gap Engineering ◽

Enhanced Photoluminescence ◽

Wet Chemical ◽

Wet Chemical Route ◽

Doped Zno ◽

Mg Doped

Download Full-text

Narrowing the band gap to enhance the resistive switching properties of Pr3+-doped ZnO thin films by Cd-ion doping

RSC Advances ◽

10.1039/c7ra07100k ◽

2017 ◽

Vol 7 (61) ◽

pp. 38757-38764 ◽

Cited By ~ 2

Author(s):

Shuai He ◽

Aize Hao ◽

Ni Qin ◽

Dinghua Bao

Keyword(s):

Thin Films ◽

Band Gap ◽

Resistive Switching ◽

Oxygen Vacancies ◽

Zno Thin Films ◽

Switching Performance ◽

Ion Doping ◽

Doped Zno

The resistive switching performance of ZnO thin films can be enhanced by decreasing the band gap and controlling oxygen vacancies.

Download Full-text

One-Pot Synthesis of Ru-Doped ZnO Oxides for Photodegradation of 4-Chlorophenol

International Journal of Photoenergy ◽

10.1155/2018/7605306 ◽

2018 ◽

Vol 2018 ◽

pp. 1-12 ◽

Cited By ~ 1

Author(s):

Maria E. Manríquez ◽

Luis Enrique Noreña ◽

Jin An Wang ◽

Lifang Chen ◽

Jose Salmones ◽

...

Keyword(s):

Band Gap ◽

Mixed Oxides ◽

Active Surface ◽

Band Gap Energy ◽

X Ray Diffraction ◽

Electron Hole ◽

One Pot ◽

Notable Increase ◽

Doped Zno ◽

The One

The photocatalytic degradation of 4-chlorophenol in water using Ru-doped ZnO mixed oxides (0, 0.5, 1, and 3 wt% RuO2) synthesized by the one-pot homogeneous coprecipitation method is reported. ZnO with wurtzite structure was present in the mixed oxide as corroborated by Raman spectroscopy and X-ray diffraction analysis. All the samples showed nanorod morphological features. The presence of Ru6+/Ru4+ couples on ZnO modified the band gap of the mixed oxides and led to a shift of the band gap energy from 3.20 eV to 3.07 eV. Ru addition increased the surface area and significantly promoted the formation of active surface oxygen species such as hydroradicals evidenced by the fluorescence spectroscopy measurement. In the photodegradation of 4-chlorophenol solution under UV irradiation, a notable increase in photoactivity was obtained as the amount of RuO2 in the mixed oxides increased to 3 wt%. The charge transfer between Ru6+/Ru4+ couples and ZnO nanoparticles together with the formation of free radical oxidant species effectively inhibits electron-hole recombination rate, thus favoring the photodegradation of 4-chlorophenol.

Download Full-text

Role of micro-strain and defects on band-gap, fluorescence in near white light emitting Sr doped ZnO nanorods

Journal of Applied Physics ◽

10.1063/1.4893562 ◽

2014 ◽

Vol 116 (9) ◽

pp. 094310 ◽

Cited By ~ 19

Author(s):

R. Udayabhaskar ◽

B. Karthikeyan

Keyword(s):

Band Gap ◽

White Light ◽

Zno Nanorods ◽

Light Emitting ◽

Doped Zno

Download Full-text

Role of Surface Band Gap Widening in Cu(In, Ga)(Se, S)2 Thin-Films for the Photovoltaic Performance of ZnO/CdS/Cu(In, Ga)(Se, S)2 Heterojunction Solar Cells

MRS Proceedings ◽

10.1557/proc-763-b8.8 ◽

2003 ◽

Vol 763 ◽

Cited By ~ 4

Author(s):

U. Rau ◽

M. Turcu

Keyword(s):

Thin Films ◽

Surface Layer ◽

Solar Cells ◽

Fermi Level ◽

Band Gap ◽

Photovoltaic Performance ◽

Heterojunction Solar Cells ◽

Fermi Level Pinning ◽

Device Efficiency

AbstractNumerical simulations are used to investigate the role of the Cu-poor surface defect layer on Cu(In, Ga)Se2 thin-films for the photovoltaic performance of ZnO/CdS/Cu(In, Ga)Se2 heterojunction solar cells. We model the surface layer either as a material which is n-type doped, or as a material which is type-inverted due to Fermi-level pinning by donor-like defects at the interface with CdS. We further assume a band gap widening of this layer with respect to the Cu(In, Ga)Se2 bulk. This feature turns out to represent the key quality of the Cu(In, Ga)Se2 surface as it prevents recombination at the absorber/CdS buffer interface. Whether the type inversion results from n-type doping or from Fermi-level pinning is only of minor importance as long as the surface layer does not imply a too large number of excess defects in its bulk or at its interface with the normal absorber. With increasing number of those defects an n-type layer proofs to be less sensitive to material deterioration when compared to the type-inversion by Fermi-level pinning. For wide gap chalcopyrite solar cells the internal valence band offset between the surface layer and the chalcopyrite appears equally vital for the device efficiency. However, the unfavorable band-offsets of the ZnO/CdS/Cu(In, Ga)Se2 heterojunction limit the device efficiency because of the deterioration of the fill factor.

Download Full-text

Effect of Yb Concentration on the Structural, Magnetic and Optoelectronic Properties of Yb Doped ZnO: First Principles Calculation

10.21203/rs.3.rs-877060/v1 ◽

2021 ◽

Author(s):

Mohamed Achehboune ◽

Mohammed Khenfouch ◽

Issam Boukhoubza ◽

Issam Derkaoui ◽

Bakang Moses Mothudi ◽

...

Keyword(s):

Band Gap ◽

Conduction Band ◽

Density Functional ◽

Blue Shift ◽

First Principles Calculation ◽

Theoretical Research ◽

Generalized Gradient ◽

Functional Theory ◽

Doped Zno ◽

Good Agreement

Abstract Density functional theory-based investigation of the electronic, magnetic, and optical characteristics in pure and ytterbium (Yb) doped ZnO has been carried out by the plane-wave pseudopotential technique with generalized gradient approximation. The calculated lattice parameters and band gap of pure ZnO are in good agreement with the experimental results. The energy band-gap increases with the increase of Yb concentration. The Fermi level moves upward into the conduction band after doping with Yb, which shows the properties of an n-type se miconductor. New defects were created in the band-gap near the conduction band attributed to the Yb-4f states. The magnetic properties of ZnO were found to be affected by Yb doping; ferromagnetic property was observed for 4.17% Yb due to spin polarization of Yb-4f electrons. The calculated optical properties imply that Yb doped causes a blue shift of the absorption peaks, significantly enhances the absorption of the visible light, and the blue shift of the reflectivity spectrum was observed. Besides, a better transmittance of approximately 88% was observed for 4.17% Yb doped ZnO system. The refractive index and the extinction coefficient were observed to decrease as the Yb dopant concentration increased. As a result, we believe that our findings will be useful in understanding the doping impact in ZnO and will motivate further theoretical research.

Download Full-text