Electrical Properties Of Zinc Oxide Research Articles

Investigation of the optical and electrical properties of zinc oxide by terahertz time domain ellipsometry

In order to demonstrate the application of terahertz time-domain ellipsometry (THz-TDE) in the characterization of wide-bandgap semiconductors, we studied two zinc oxide (ZnO) single crystals with different conductivities. The optical properties of ZnO samples with low conductivity and high conductivity are both obtained by ellipsometric parameters, while the electrical properties of ZnO sample with high conductivity are well deduced and fitted using the Drude model. These results suggest that THz-TDE can effectively obtain the optical and electrical properties of wide-gap semiconductors and can be used to characterize semiconductors with carrier densities higher than 1016 cm−3.

EFFECT OF NIOBIUM DOPANT CONCENTRATION ON ZNO NANOSTRUCTURES ON SI POROUS SUBSTRATE

Zinc oxide (ZnO) nanostructures have gained popularity in sensor technology due to their unique properties and facile device integration. However, the intrinsic optical and electrical properties of ZnO are suboptimal for direct industrial applications, necessitating enhancements through doping. This study investigates the impact of niobium (Nb) doping concentrations on the physical, optical, and electrical characteristics of ZnO nanostructures. FESEM analyses indicate successful deposition of ZnO on silicon nanoparticles substrates, with nanostructure sizes peaking at 88 nm and 115 nm for 6% and 8% Nb dopant concentrations, respectively. XRD results suggest that the structural integrity of the nanostructures is maintained up to a 10% doping level, with an optimal concentration at 6%. UV-Vis spectroscopy shows a shift in the absorption peak into the visible range and a decrease in maximum reflectivity from 47.5990% at 2% doping to 40.9205% at 6% doping, indicating enhanced light absorption suitable for optoelectronic applications. Electrical measurements reveal that a 6% Nb dopant concentration yields the lowest resistivity and highest conductivity among the tested samples. These findings underscore the potential of Nb-doped ZnO nanostructures in improving the performance of optoelectronic devices through tailored doping strategies.

Structural, Optical, Magnetic and Electrical Properties of Sputtered ZnO and ZnO:Fe Thin Films: The Role of Deposition Power

Structural, optical, magnetic, and electrical properties of zinc oxide (henceforth, ZO) and iron doped zinc oxide (henceforth, ZOFe) films deposited by sputtering technique are described by means of Rutherford backscattering spectrometry, grazing incidence X-ray diffraction, scanning electron microscope (SEM), UV–Vis spectrometer, vibrating sample magnetometer, and room temperature electrical conductivity, respectively. GIXRD analysis revealed that the films were polycrystalline with a hexagonal phase, and all films had a preferred (002) c-axis orientation. The lattice parameters a and c of the wurtzite structure were calculated for all films. The a parameter remains almost the same (around 3 Å), while c parameter varies slightly with increasing Fe content from 5.18 to 5.31 Å throughout the co-deposition process. The optical gap for undoped and doped ZO was obtained from different numerical methods based on the experimental data and it was increased with the increment of the concentration of Fe dopant from 3.26 eV to 3.35 eV. The highest magnetization (4.26 × 10−4 emu/g) and lowest resistivity (4.6 × 107 Ω·cm) values of the ZO films were found to be at an Fe content of 5% at. %. An explanation for the dependence of the optical, magnetic, and electrical properties of the samples on the Fe concentrations is also given. The enhanced magnetic properties such as saturated magnetization and coercivity with optical properties reveal that Fe doped ZO thin films are suitable for magneto-optoelectronic (optoelectronic and spintronics) device applications.

High performance optical and electrical properties of zinc oxide reinforced poly(diphenylamine) nanocomposites for optoelectronic applications

AbstractPolymer nanocomposites with good optical, crystalline, morphological, thermal, dielectric, and electrical properties were synthesized using poly(diphenylamine) (PDPA) and zinc oxide (ZnO) nanoparticles. The redshift in the UV absorption edges of composites indicates that ZnO nanoparticles have been successfully incorporated into the PDPA matrix. The lowest optical bandgap energy and maximum refractive indices were observed in 7 wt% loadings. The narrowing of the avearge chain spacing detected by X‐ray diffraction (XRD) proved that ZnO had an impact on the structure of PDPA. Scanning electron microscopy (SEM) images show homogeneous dispersion of spherically shaped ZnO nanoparticles at lower filler loadings. The glass transition temperature of the nanocomposites was greatly enhanced with the addition of nanoparticles analyzed by differential scanning calorimetry. The electrical and dielectric properties improved with temperature and nanoparticle loadings up to 7 wt%. The analysis of impedance spectra and the decreasing radius of semi‐circular arcs in the Nyquist plot manifests the existence of temperature‐dependent conductivity and relaxation phenomenon. The experimental values of DC conductivities were correlated with different theoretical conductivity models and the McCullough model was found to be the most promising one to explain the increased DC conductivity of the PDPA/ZnO nanocomposites.

Enhanced the Cu2+ doping on the structural, optical and electrical properties of zinc oxide (ZnO) nanoparticles for electronic device applications

Zinc oxide (ZnO) and Cu doped ZnO Nano particles (NP's) were synthesized through chemical route (sol gel & Co-precipitation) to reveal their structural, electrical and optical properties. The synthesized NP's have been characterized by X-Ray diffraction (XRD), Fourier transform infrared rays (FTIR) spectroscopy, Ultra violet visible (UV–V) spectroscopy and impedance spectrometry techniques. XRD pattern revealed the formation of hexagonal structure of ZnO NP's. However size variation of ZnO NP's was observed with addition of Cu contents. SEM analysis revealed that nanorods have been made due to Cu doping in ZnO NP's. FTIR spectroscopy determined the presence of Cu contents in the synthesized samples while UV-technique shown the absorption peaks in the range of 200–800 nm range. The band gap energy decreases with increasing Cu content was observed. The microwave dielectric properties (i.e. relative permittivity & tangent loss) of the Cu doped samples were observed to be decrease with resonant frequency.

A comparative study of structural, mechanical & electrical properties of ZnO and AlN thin films for MEMS based piezoelectric sensors

In this work, a comparative study has been carried out to compare the relative performance of ZnO (Zinc Oxide) and AlN (Aluminum Nitride) thin films for their application in piezoelectric sensors. The thin films material properties are being characterized using various material characterization techniques such as SEM, XRD, and Nanoindentation. Further the MIM (Metal-Insulator-Metal) based devices have been fabricated with piezoelectric films sandwiched between Al electrodes. The devices have been evaluated for mechanical and electrical performances. The natural frequency of the devices recorded as 46.8 kHz (ZnO) and 40.8 kHz (AlN). The average nominal capacitance of the MIM structure is measured as ∼98 pF and ∼120 pF where as corresponding dissipation factor obtained as ∼0.03 and ∼0.0005 respectively for ZnO and AlN devices. The repeatability investigation carried out on the sample devices for up to 90 days and the output has been monitored. The result showed that the AlN devices exhibit better output stability compared to ZnO devices.

Modification in structural, optical, morphological, and electrical properties of zinc oxide (ZnO) nanoparticles (NPs) by metal (Ni, Co) dopants for electronic device applications

In the present work, Zinc Oxide (ZnO) nanoparticles (NPs) were synthesized by the chemical co-precipitation method using Zinc Chloride as the initial chemical, while Nickel and Cobalt chloride as dopants. Phase identification of metal (Ni, Co) doped Zinc Oxide nanoparticles (NPs) was observed using x-ray diffraction (XRD). The small lattice distortion or phase changes appeared due to shifting of diffraction angles peaks towards larger angle in ZnO are corresponded to metal (Ni, Co) dopant. The average crystallite size appears to decrement in NP size from 7.67 nm to 6.52 nm and 5.35 nm to 5.17 nm with increasing 5 % to 80 % of metal (Ni, Co) dopant respectively. The optical characteristics, including the absorption spectra of the prepared sample were observed through UV–Vis spectroscopy, Meanwhile SEM confirmed the observation of composition change in specimen with metal (Ni, Co) dopant concentration. The bandgap value was also found decrement 5.23 eV to 5.05 eV with increment of metal (Ni, Co) dopant concentration. The functional groups were measured by Fourier transformation infrared spectroscopy (FTIR ) . FTIR peaks found the metal (Ni, Co) doped ZnO with the vibration mode of (Zn 2+ –O 2− ) ions due to the increment of dopant concentrations. Furthermore, electrical results show the ohmic behavior of prepared samples. These findings indicate the possibility of tuning optical, structural and electrical properties of metal (Ni, Co) doped ZnO with various dopant concentrations of Nickel and will have great potential to find application in optoelectronic devices.

Enhanced Electrical Properties of Alkali-Doped ZnO Thin Films with Chemical Process

Doped ZnO are among the most attractive transparent conductive oxides for solar cells because they are relatively cheap, can be textured for light trapping, and readily produced for large-scale coatings. Here, we focus on the development of alternative Na and K-doped ZnO prepared by an easy low-cost spray pyrolysis method for conducting oxide application. To enhance the electrical properties of zinc oxide, alkali-doped Zn1−x MxO (x = 0.03) solid solutions were investigated. The resulting layers crystallize in a single hexagonal phase of wurtzite structure with preferred c-axis orientation along a (002) crystal plane. Dense, well attached to the substrate, homogeneous and highly transparent layers were obtained with great optical transmittance higher than 80%. The optical energy band gap of doped ZnO films increase from 3.27 to 3.29 eV by doping with Na and K, respectively. The electrical resistivity of the undoped ZnO could be decreased from 1.03 × 10−1 Ω.cm to 5.64 × 10−2 Ω.cm (K-doped) and 3.18 × 10−2 (Na-doped), respectively. Lastly, the carrier concentrations increased from 5.17 × 1017 (undoped ZnO) to 1 × 1018 (doped ZnO).

Tunning the electronic structure and optical properties of ZnO doped with different concentrations of Mg atom: The first principles study

The effects of Mg atom doping on the energy band structure, density of states and corresponding optical and electrical properties of zinc oxide was explored. The results show that Mg doping will cause the crystal lattice volume of zinc oxide crystals to become larger. As the concentration of Mg atoms increases, its energy band gap becomes larger and larger, and its energy band structure is well adjusted, and the size is controllable. The doping of Mg element has a good control on the electrical and optical properties of ZnO. This indicates that Mg doped ZnO has a great influence on its electronic structure and optical properties, which provides a theoretical basis for further research on the effect of doping on the properties of ZnO.

Impact of Deposition Rate on the Structural, Optical, and Electrical Properties of Zinc Oxide (ZnO) Thin Films Prepared by Solar Spray Pyrolysis Method

Impact of Deposition Rate on the Structural, Optical, and Electrical Properties of Zinc Oxide (ZnO) Thin Films Prepared by Solar Spray Pyrolysis Method

Tailored piezoelectric performance of self‐polarized PVDF‐ZnO composites by optimization of aspect ratio of ZnO nanorods

AbstractAspect ratio of filler plays a crucial role to study the electrical properties of polymer based composite system. Here, we investigated the effect of filler aspect ratio on the electrical properties of zinc oxide (ZnO) incorporated poly(vinylidene fluoride) (PVDF) matrix. ZnO nanorods having different aspect ratio were synthesized by the hydrothermal technique with varying reaction time 4 to 20 hours at a fixed temperature and PVDF based nanocomposites of the respective ZnO nanorods with different wt% filler loading were fabricated. Interestingly polar‐phase fraction increased with the aspect ratio of ZnO nanorods. The nanocomposites with higher aspect ratio ZnO nanorods showed an increased energy density under same electric field and exhibited maximum open circuit AC output voltage (ie, 20 V) after the application of repeated human finger tapping. This result indicates that high aspect ratio ceramic filler provides an effective approach to enhance the dielectric, ferroelectric, energy storage, and energy harvesting performances of ceramic‐polymer nanocomposites.

Synergic effect of Zinc (Zn) precursors on the microstructural, optical and electrical properties of Zinc oxide thin films for solar cell applications

Zinc oxide (ZnO) nanoparticles, with their inimitable characteristics such as easy synthesis, high selectivity and enhanced cytotoxicity are becoming progressively important candidate in modern applications. In this study, we have systematically investigated the effect of fabrication conditions on the morphological, structural, optical and electrical properties of zinc oxide (ZnO) thin films. It was observed that the change in Zn-precursor leads to the growth of grains structure at the surface of ZnO thin films. Broadly mentioned, two different regions of growth were observed with the change in the Zn precursor medium. The presence of ZnO hexagonal structure wurtzite was confirmed with the help of non-destructive X-ray Diffraction (XRD) analysis. Scanning Electron Microscopy (SEM) showed that the islands of nano-grains started to nucleate into highly stressed, uniform and roughly compact morphology of the ZnO grains structures of the crack-free thin films. The as-fabricated ZnO thin films comprised of micro and nanoparticles grains structures. The electrical properties measurement revealed the decrease in the average resistivity with the change in Zn-precursor solution of the as-fabricated ZnO thin films. The UV–Vis. Spectroscopy showed the optical absorption spectra of the ZnO thin films have maximum transmittance in the visible region i.e. 80 %. Such kind of films characteristics are very important for solar spectra. It was observed that the change in Zn precursor solution has impact on the transmittance properties of the ZnO thin films. This study highlights an environment friendly, low cost and facile roots for the fabrication of ZnO thin films for probable use in solar cells applications.

Study the effect of dip in reaction temperature on thermal and electrical properties of ZnO nanoparticles

The present study reports thermal and electrical properties of Zinc oxide (ZnO) nanoparticles prepared using co-precipitation route. Sudden dip in reaction temperature observed during the synthesis process created defects in the crystal lattice of ZnO which leads to reduction in crystallite size from 33 nm to 28 nm with increase in reaction temperature. This is confirmed by the X-ray diffraction studies. Thermal analysis of the samples shows better thermal stability for smaller nanoparticles. Temperature-dependent current-voltage characteristics of the ZnO samples show reduction in the conductivity and increase in dielectric constant with respect to rise in reaction temperature. Increase in dielectric constant with decrease in size of nanoparticles may be useful in the field of nanoelectronics like memory-storage devices, etc.

Effect of erbium-calcium manganite doping on microstructure and electrical properties of zinc oxide based varistor ceramics

In this research, (80-x) mol% zinc oxide with 20 mol% CaMnO 3 as the additive and (x) mol% erbium oxide Er 2 O 3 as the doping material where x = 0.5, 1.0 and 1.5. Aims of this work are to elucidate the effects of doping material on microstructure ZnO and nonlinear characteristics of ZnO based varistor ceramics. A compound comprising ZnO-CaMnO 3 -Er 2 O 3 underwent pre-sintering at 500 °C for 4 hours and sintering process at temperature of 1100 °C, 1200 °C and 1300 °C with the soaking time of 1.5 hours and 4.5 hours. X-ray diffraction patterns confirmed the presence of CaMnO 3 spinal and additional phases containing Er in the synthesized compounds. The disappeared of hydroxyl and carbonyl functional group was observed at 3600-3650 cm-1, 1421 cm-1 and 875 cm-1 respectively by Fourier Transform Infrared spectroscopy to indicate the starting formation oxide metal upon calcinations.

Engineering of optical and electrical properties of ZnO by non-equilibrium thermal processing: The role of zinc interstitials and zinc vacancies

A controlled manipulation of defects in zinc oxide (ZnO) and the understanding of their electronic structure can be a key issue towards the fabrication of p-type ZnO. Zn vacancy (VZn), Zn interstitials (IZn), and O vacancy (VO) are mainly native point defects, determining the optoelectronic properties of ZnO. The electronic structure of these defects still remains controversial. Here, we experimentally demonstrate that the green emission in ZnO comes from VZn-related deep acceptor and VZn-VO clusters, which is accompanied by the radiative transition between the triplet and the ground singlet state with the excited singlet state located above the CB minimum. Moreover, the IZn is identified to be a shallow donor in ZnO, being mainly responsible for the n-type conductivity of non-intentionally doped ZnO.

Electrical properties of zinc oxide – Tetracene heterostructures with different n-type ZnO films

Electrical properties of organic-inorganic p–n heterojunction structures with tetracene (Tc) and zinc oxide (ZnO) films were investigated. The ZnO films had different n-type carrier concentrations that varied from ∼1015 cm−3 to 1019 cm−3. Lower n-type ZnO layers resulted in decreased reverse currents in the ZnO:Al/ZnO/Tc/Au structures and in an improvement of their asymmetric properties. Experimentally determined energy level alignments at the ZnO/Tc interfaces were related to the electrical behavior of the structures. An improved rectification was associated with decreased generation-recombination currents at the ZnO/Tc interface due to an increased organic-inorganic interface energy gap. Current-voltage characteristics were analyzed by a differential approach. Electrical conduction mechanisms including bimolecular recombination as well as trap-filled limited conduction were identified in the investigated structures.

Effect of Fe doping on the electronic structure, optical and electrical properties of ZnO compound: Ab initio insights

By means of first-Principe method within TB-mBJ approach and Boltzmann transport equations, the electronic structure, optical and electrical properties of zinc oxide doped with Iron are investigated. Both calculated band gap and lattice parameters of pure ZnO are found to be in reasonable agreement with the experimental measurements. Furthermore, the doping ZnO with Fe leads to the appearance of some deep impurity levels in the band gap arisen from Fe-3d states. Indeed, these deep level donors enhance the infrared and visible-light absorption. Besides, we notice that the electrical conductivity is enhanced while the carrier mobility is decreased after Fe doping.

Effects of electric fields on the conduction of polyvinyl alcohol (PVA)/ZnO films by photoluminescence analysis

We verified the electrical properties of zinc oxide (ZnO) and hydrated polyvinyl alcohol (PVA)/ZnO films under the influence of electric field through photoluminescence (PL) analysis. The ZnO films were deposited by sputtering on A-N-B substrates that had nonconductive areas (N) between A and B electrodes. The PVA/ZnO films were prepared by spin-coating PVA gel on top of the ZnO film. Current–voltage (I–V) data analysis showed that the conductivity values of the ZnO films significantly increased in the presence of PVA gel. Large amounts of free electrons and oxygen vacancies (Vo) were generated by the chemisorption reaction of PVA gel with ZnO and detected by PL spectra produced without the presence of an electric field (0V). The Fermi-energy level for a PVA/ZnO film approaches the conduction band of ZnO because of many free electrons in the film. The variations of both the free electron and Vo densities for ZnO and PVA/ZnO films were analyzed using PL spectra in the presence of various electric fields (>0V). The conduction mechanism of PVA/ZnO was explained and related to the variations of both the free electron and Vo densities as revealed by the PL spectral analysis.

Role of hexamethylenetetramine concentration on structural, morphological, optical and electrical properties of hydrothermally grown zinc oxide nanorods

Zinc oxide (ZnO) nanorods were grown on the glass substrates using hydrothermal method. Influence of hexamethylenetetramine (HMTA) concentration on the morphological, structural, optical and electrical properties of ZnO was investigated. Increasing HMTA concentration produces dense growth of nanorods and decreases the diameter from ~450 to ~150 nm and also modified the hexagonal shape of ZnO nanorods to circular shape. X-ray diffraction spectra revealed that the synthesized ZnO nanorod exhibits wurtzite structure. Shifting of absorbance edge from 3.30 to 3.36 eV with increasing concentration of HMTA was observed in the UV–Vis spectra. Photoluminescence studies showed the presence of defect related peaks such as zinc interstitial and oxygen vacancies. The observed blue shift in UV emission peak from 387 to 361 nm in photoluminescence spectrum also confirmed the decrease in the size of nanorods. Electrical studies showed the increase in the resistance with the increase in the HMTA concentration from 1.17 to 16.9 kΩ due to dense and reduced size of nanorod networks.

Fundamental Properties of One-Dimensional Zinc Oxide Nanomaterials and Implementations in Various Detection Modes of Enhanced Biosensing.

Recent bioapplications of one-dimensional (1D) zinc oxide (ZnO) nanomaterials, despite the short development period, have shown promising signs as new sensors and assay platforms offering exquisite biomolecular sensitivity and selectivity. The incorporation of 1D ZnO nanomaterials has proven beneficial to various modes of biodetection owing to their inherent properties. The more widely explored electrochemical and electrical approaches tend to capitalize on the reduced physical dimensionality, yielding a high surface-to-volume ratio, as well as on the electrical properties of ZnO. The newer development of the use of 1D ZnO nanomaterials in fluorescence-based biodetection exploits the innate optical property of their high anisotropy. This review considers stimulating research advances made to identify and understand fundamental properties of 1D ZnO nanomaterials, and examines various biosensing modes utilizing them, while focusing on the unique optical properties of individual and ensembles of 1D ZnO nanomaterials specifically pertaining to their bio-optical applications in simple and complex fluorescence assays.