Undoped CdO Research Articles

Effect of Cr doping and photoresponse properties of photodiode based on CdO thin films

AbstractCadmium oxide (CdO) and chromium (Cr) doped CdO thin films with various Cr wt% contents (0.1, 0.5, 1, 2 at.%) are synthesised on soda lime glass (SLG) substrates. Results from X-ray analysis indicate that all thin films are in cubic nature with (111) preferential orientation. Cr doping does not appear to result in a transition from one crystal phase to another. CdO with the 2.0 wt% Cr doping absorbs much more light than undoped CdO in low wavelength region (< ≈450 nm), giving a maximum absorption peak in the ultraviolet region. Cr doped CdO/p-Si heterojunction shows the Cr wt% content-sensitive rectification property, achieving a high ratio of 105. In addition, Cr doped CdO/p-Si heterojunction exhibits photodiode behavior and possesses an improved photo-to-dark current ratio of ≈153. This work introduces an occasion to develop the optoelectronic devices based on Cr doped CdO thin films.

Insights into the consequence of (Al–Zn) dual-doping on structural, morphological, and optoelectrical properties of CdO thin films

The present study explores the structural, morphological, optical, and electrical properties of spray pyrolyzed (Al–Zn) dual-doped CdO thin films. The un-doped and (Al–Zn) dual-doped CdO thin films have been deposited on glass substrate using spray pyrolysis route at 325 °C. The physical properties of the doped samples were analyzed as a function of Zn concentration (2–5 mol%) with constant Al (3 mol%) concentration. XRD analysis confirms the successful incorporation of (Al–Zn) dual-doping into CdO crystal as well as the polycrystalline nature was evident. No phase transitions were apparent from XRD data while revealing the single cubic structure of all the samples. The surface morphology of the samples studied by SEM. It shows the formation of rock-shaped microstructure and the variation of grain size with doping concentrations. Optical analysis was done using UV–vis spectroscopy within the range of 300–1200 nm. Maximum value of transmittance was attained for 3% (Zn–Al)-doped CdO sample. The dual doping exhibits the broadening of band gap values (2.61–3.84 eV) whereas a decrease in extinction coefficient was noticed as a function of Zn doping concentration. Electrical analysis was done using the four-probe method and a high resistivity was seen for higher Zn concentration. Obtained results and precise comparison with some similar films suggested that 2% Zn and 3% Al co-doping can be a suitable candidate for optoelectronic devices.

Analysis and characterization of molybdenum-doped cadmium oxide

Molybdenum-doped cadmium oxide films were prepared by a spray pyrolysis technique at substrate temperature of 300 °C. The effect of doping on structural, electrical and optical properties were studied. X-ray analysis shows that the undoped CdO films are preferentially oriented along the (111) crystallographic direction. Molybdenum doping concentration increases the films’ packing density and reorients the crystallites along the (200) plane. A minimum resistivity of 4.68 10−4 Q cm with a maxi- mum mobility of 75 cm2 V−1 s−1 is achieved when the CdO film is doped with 0.5 wt.% Mo. The band-gap value is found to increase with doping and reaches a maximum of 2.56 eV for 0.75 wt.% as compared to undoped films of 2.2 eV.

ZnO/CdO island-like porous nanocomposite as an ultra-sensitive sensor for BTX detection at room temperature

In this work, the major challenge is to study the enhancement of sensing properties at room temperature as it holds great promise for minimizing the detrimental effects on human health and the environment. For the progress of such highly sensitive gas sensors, a strategy is to tune the properties by nanocomposite sensor ZnO/CdO (ZCO) derived by co-precipitation method towards Benzene, Toluene, and Xylene (BTX) vapours is reported. The characterization of the undoped ZnO, CdO nanoparticles, and ZCO nanocomposites were systematically studied by X-ray diffraction (XRD), XPS, Raman spectroscopy, UV–Vis, SEM, and gas sensing study. XRD results confirmed the crystallinity of the synthesized samples, and SEM revealed the island-like porous morphology of the ZCO sample. The BTX gases at room temperature have shown excellent response to the ZCO sensor for 15 ppm concentration with a quick response and recovery times (Benzene-12 s and 9 s, Toluene- 36 s and 48 s, Xylene- 32 s and 28 s), respectively. Based on the unique morphology, low synthesis cost, and excellent selectivity of BTX gases, the ZCO nanocomposite is a suitable sensor for BTX detection in a natural environment.

Investigations of Structural, Optical, Thermal, and spectroscopic characteristics of CdO-Ni nanoparticles employed in anti-cancer activities for cancer cells

In this communication, CdO doped with Ni was employed for new biological applications as an anti-cancer. However, the prepared system needed to be identified through the typical characterizations. The Cd1-xNixO system was utilized by the Co-precipitate calcinations method. To enhance the availability and processability of the materials, and be as sure of achieving the nanomaterials, X-ray diffraction (XRD) analysis indicated exhibited a polycrystalline structure with distinctive structural parameters—however, the single phase Cd1-xNixO exhibits nanoscale material.The optical band gap of the samples was determined using diffused reflectance spectra analysis, revealing Eg values of 2.19 eV for undoped CdO and ranging from 1.62 to 2.12 eV for Ni-doped CdO samples at varying concentrations of Ni.Thermal stability measurements were conducted using a Thermogravimetric analyzer (TGA) in the temperature range from room temperature to 1000 °C at a rate of 15 deg/min. Furthermore, the cytotoxicity effect of the synthesized Cd1-xNixO samples was evaluated against four different cancer cell lines: breast carcinoma (MCF-7), human hepatoblastoma (HepG2), human lung adenocarcinoma (A549), and human breast cancer (MDA-MB-231).Overall, these findings provide valuable insights into the properties of Cd1-xNixO nanostructures synthesized via the Co-precipitate calcinations method and their potential applications in various fields, including optoelectronics and biomedical sciences.

Characterization of CuO doped CdO nanomaterials synthesized by sol gel spin coating and hydrothermal method

CuO-CdO nanomaterials were synthesized by sol gel spin coating and hydrothermal methods. Undoped CdO and 0.2%, 0.5%, 1%, and 2% CuO doped CdO were produced as thin films and nanopowders. The structural, optical, and electrical properties of the thin films and nanopowders produced were investigated. It was determined by X-ray diffraction (XRD) analysis that thin films and nanopowders were polycrystalline and face-centered cubic structures. From Atomic Force Microscope (AFM) images, it was observed that the structure of the thin films was homogeneous and dense rod-shaped structures, and the nanopowders were urchin-like structures consisting of spherical nanoparticles from the Field Emission Scanning Electron Microscopy (FESEM) images. It was determined that nanopowder and thin films have direct band transition from Ultraviolet–visible spectroscopy (UV–Vis) analysis. From all the results obtained, it was concluded that structural, optical, and electrical properties of thin films and nanopowders vary depending on the doping rate and method differences.

Preparation and investigation of the structural and optical characteristics of manganese- doped cadmium oxide films

In this paper, undoped and Mn-doped CdO thin films deposited on the glass substrates by the chemical spray pyrolysis method (CSP) technique. The prepared thin films characterized by XRD, AFM, FESEM and UV visible. The results of the X-ray diffraction patterns revealed that the prepared films have a polycrystalline structure and a cubic structure. The crystallite size (D) value for all prepared films was calculated using Scherrer's method, Williamson-Hall method and size strain plot (SSP) method, from the results, it was observed that, the crystallite size decreases with increase in doping ratio of Manganese. The optical propertis show that with an increase in Mn concentration, the CdO films' transparency and the energy gap of the films increases. The Hall effect measurement revealed that all prepared films have negatives type (n-type) charge carriers, the value of the doping ratio rises, the Hall coefficient decreases.

Tailoring properties of nano-crystalline CdO thin films by incorporation of Al for enhanced photo-voltaic applications

Nano-crystalline thin films of Al doped and undoped CdO thin films were successfully deposited using home-built spray pyrolysis unit. The consequence of Al in CdO was explored and found that the doping of Al has influenced the characteristics of CdO. The CdO was doped with varying concentration of Al viz.0, 0.1, and 10 At.%. The physical, optical and morphological properties were analyzed. These films showed a preferential growth along [111] and [020] direction. The reduction in lattice parameter found to be, the undoped film had lattice parameter of 4.6833×10-10 m whereas, 10 At.% had 4.6819×10-10 m. All crystallites were below 50 nm and grain size was estimated using Scherrer and Williamson-hall plot. The 0.1 At.% of Al showed a larger absorbance whiled 10 At.% had the lowest absorbance. Which is also reflected in transmittance. All film showed transmittance from 70% to 86%. The 10 At.% had the largest transmittance. The reduction in bandgap was observed 10 At.% has the lowest bandgap of 2.04 eV against undoped which has a bandgap of 2.37 eV. The 10 At.% Al film showed an average reflectance of 0.061 at 700 nm whereas; undoped film has an average reflectance of 0.083. The refractive index found to decrease as the doping concentration increases. The electrical conductivity was estimated from optical analysis and found that the electrical conductivity found to increase from 4.7×104 S/cm to 5.2×104 S/cm as the concentration of Al is increased. Haacke’s figures of merit (φH) was calculated and found that doping has increased the φH. 10 At.% showed 8.23×10-3cm-1. Nonlinear optical parameters were also studied. The Scanning electron microgram suggests the incorporation of Al has increased in density of particles in the film. Hence, the developed nano-crystalline CdO thin films by incorporation Al for enhanced photo-voltaic applications.

Structural and optical properties of CBD synthesised CdO thin films: influence of Ni incorporation

ABSTRACT The effect of nickel doping on different properties of thin films prepared by chemical bath deposition (CBD) routes was very much important for detailed study of doped metal oxides. The structural and optical characterisation of the deposited films was done using X-ray diffraction, EDX, UV-Vis spectroscopy, etc. XRD patterns of the samples indicate that both undoped and Ni-doped CdO thin films have polycrystalline cubic cadmium oxide structure. Details analysis of XRD patterns confirms an enhancement in grain size and lowering in average microstrain due to nickel doping. The optical absorption method is used to determine the optical band gap of undoped and Ni-doped CdO thin films and the measured value was in the range of 2.26–2.60 eV. The E g values of the CdO films decrease with the increase of dopant content in the film. It is estimated that the optical band gap and grain size of the CdO film can be controlled by doping with nickel atoms.

STUDYING THE EFFECT OF AG DOPING ON THE STRUCTURAL AND OPTICAL PROPERTIES OF CDO THIN FILMS PREPARED BY CHEMICAL SPRAY PYROLYSIS METHOD

In this work, thin films of undoped and Ag-doped CdO with (1and 3) wt.% were prepared by using spray pyrolysis method on glass substrate at of 350ºC with films thicknesses of (160-190) nm using spraying rate and pyrolysis time is 5 ml/min an 5sec respectively. The X-ray diffraction investigated the structural types of the CdO thin films after and before doped by Ag, XRD analysis showed that CdO:Ag films are highly polycrystalline and exhibit cubic crystal structure with (111) preferred orientation. However, the peak for all CdO:Ag films became more intense with a slight variation. The optical properties measure by ultra violet spectra, the optical study shows the spectral transmission and the optical energy band gap increases from 64.77% and 2.50 eV to 71.11% and 2.70 eV respectively depending upon the Ag content in the films, in contrary with the absorbance that increases with the decrease in wavelength and decreases with the increasing Ag doping concentration.

Analysis and characterization of molybdenum-doped cadmium oxide

Molybdenum-doped cadmium oxide films were prepared by a spray pyrolysis technique at substrate temperature of 300 °C. The effect of doping on structural, electrical and optical properties were studied. X-ray analysis shows that the undoped CdO films are preferentially oriented along the (111) crystallographic direction. Molybdenum doping concentration increases the films’ packing density and reorients the crystallites along the (200) plane. A minimum resistivity of 4.68 10−4 Q cm with a maxi- mum mobility of 75 cm2 V−1 s−1 is achieved when the CdO film is doped with 0.5 wt.% Mo. The band-gap value is found to increase with doping and reaches a maximum of 2.56 eV for 0.75 wt.% as compared to undoped films of 2.2 eV.

Electrical resistivity and magnetic susceptibility of substoichiometric CdO and In doped CdO films

Undoped and In doped substoichiometric CdO nanostructured films were prepared via vapor transport method. Mixed phases of hexagonal Cd and cubic CdO were obtained. No peaks related to In or indium oxides were observed in the In doped CdO pattern. Net-like assembles of nanowires were observed for undoped CdO sample whereas a regular morphology of equally shaped grains was observed for In doped CdO sample. The evaluated room temperature electrical resistivity values for undoped and In doped CdO films were 1.56 × 102 and 2.31 × 10–2 Ωcm, respectively. The temperature dependent resistivity measurements elucidated the semiconducting behavior for undoped CdO films, whereas a semiconductor–metal with a transition around 367 K was obtained for In doped CdO film. The magnetic susceptibility showed paramagnetic-antiferromagnetic transition with Neel temperatures of 266 and 308 for undoped and In doped CdO samples, respectively.

Enhancing the properties of CdO thin films by co-doping with Mn and Fe for photodetector applications

In this communication, we report on how the co-doping of two transition metal ions (Fe and Mn) effectively improves the structural, morphological, optical, electrical and photodetection properties of CdO thin films than individual doping. For this, pure-CdO, Fe-doped, Mn-doped and (Fe-Mn) co-doped CdO thin films are deposited by spray pyrolysis technique. X-ray diffraction (XRD) patterns reveal that these films possess cubic structure and belong to the Fm-3 m space group. The Field Emission Scanning Electron micrographs hold a qualitative agreement with the crystalline sizes obtained from the XRD analysis. Energy Dispersive X-Ray Analysis approved the existence of constituent elements in the prepared films. The photoluminescence spectra identified the quality of crystal structure and the presence of defects in the prepared films. Analyzing the absorption spectra unveiled the direct bandgap values in the range 2.32 eV (for pure-CdO) - 1.96 eV (for CdO:Fe(1%):Mn(1%)). The Hall Effect measurements established n-type behavior with the values of resistivity (ρ), carrier concentration (n) and carrier mobility values in the range 5.8–7.1 mΩcm, 6.7−2.4 × 1019 cm−3 and 16−37 cm2/Vs, respectively. Three different transport mechanisms such as ohmic, recombination-tunneling and space-charge limited current are found to play roles in the three distinct ranges of the I–V data measured for the films under study. The ideality factor values are obtained from the region where the recombination-tunneling mechanism is prevalent. The photoelectric parameters such as photo-responsivity, and external quantum efficiency are obtained. The values of these quantities pertaining to pure-CdO, CdO:Mn, CdO:Fe and CdO:Fe:Mn films vary in the range 128.4–561.3 mA/W, and 30–131.1 %, respectively. From the current study, it was found that photoresponsivity and external quantum efficiency are enhanced by a factor of four in codoped CdO films than the undoped CdO film and can find potential photodetector applications.

Effect of Divalent Metal Ions on Thermal Evolution and Band Gap Energy of Cadmium Oxide (CdO) Nanocrystallites: Comparetive Study

In this study, pure and divalent metal ions doped cadmium oxide samples are synthesized by cost effective co-precipitation method at the nanoscale dimensions. Here, we have represented a comprehensive study which conclude that how structural and optical behavior of undoped cadmium oxide has been modified with single doping of Cu, Mn and their co-doping (Cu-Mn) also. The prepared nanopowder is being investigated using different complementary techniques like TG-DTA and UV-Vis spectroscopy to explore their bandgap energy and thermal behavior. A strong and broad optical absorption band is obtained at 262, 250, (312 and 475), (250-350) nm for respectively samples. The optical band gap values are calculated using Tauc’s plot as 4.45, 3.86, 2.39 and 2.44 eV for undoped CdO, Cu doped CdO, Mn doped CdO and Cu-Mn co-doped CdO respectively. UV-Vis spectra revealed that the prepared samples are having high absorbance and extended sufficiently into visible region. Therefore, it is suggested that the co-doping efficiently alter the band gap of the CdO and make it suitable for optoelectronics and other applications like gas sensing, photo catalyst etc.

Influence of incorporation of carbon on the transparent conducting properties of CdO thin films

Thin films of CdO incorporated with different amounts of carbon element have been deposited on glass substrates by using the vacuum thermal evaporation method aiming at improving their transparent conducting (TC) properties. The structural and opto-electrical properties of the host CdO films were systematically studied. X-ray diffraction and optical investigations confirmed the inclusion of C species in the CdO lattice. The obtained results were explained through the occupation of interstitial positions and structural vacancies of the host CdO lattice by C species. It was observed that the inclusion of carbon into the CdO lattice blue-shifted the optical band gap by $${\sim }5{-}7$$ %, which was attributed to the Moss–Burstein (B–M) effect. The electrical studies showed that the carrier mobility increased steadily with the increase in the C% inclusion level, so that with 5 wt% it attained $${\sim }7.5$$ times the carrier mobility in un-doped CdO. Therefore, the present study showed that the prepared host CdO–C films have controllable TC degenerate semiconducting properties, which could be required in different optoelectronic applications.

Structural, optical, electrical and catalytic properties of precursor solution-aged spray deposited undoped, Zn-doped and Ag-doped CdO thin films

Photocatalytic performance of precursor solution-aged undoped, Zn-doped CdO (CdO:Zn) and Ag-doped CdO (CdO:Ag) thin films has been reported in this paper. Perfume atomizer is adopted to deposit the films. CdO, CdO:Zn and CdO:Ag thin films exhibit cubic crystal structure. The crystallite size values were 34, 31 and 27 nm, respectively, for the CdO, CdO:Zn and CdO:Ag thin films. In the EDX spectra of the CdO:Zn and CdO:Ag thin films, Zn and Ag were observed along with Cd and O. The CdO:Zn and CdO:Ag thin films exhibit increased transparency and widened band gap values. PL spectra showed peaks related to oxygen vacancies for all the films. Reduced resistivity was evinced for the CdO:Zn and CdO:Ag thin films. The degradation efficiencies of the CdO, CdO:Zn and CdO:Ag thin films against methyl orange after 75 min light exposure were 76.4, 84.3 and 90.4%, respectively. The CdO:Zn and CdO:Ag catalysts exhibit satisfactory stability with better reusable nature and are suitable for the effective treatment of organic toxic dyes.

Tuning the energy bandgap and nonlinear absorption coefficients of CdO nanocomposite films with doping and annealing process

The effects of doping and annealing on the linear and nonlinear optical properties of CdO, CdO:Cr and CdO:Sb nanocomposite films are investigated. The nanoparticles were synthesized with hydrothermal method. Their films were obtained by spin coating method. The XRD measurements exhibited that all synthesis nanoparticles are in cubic structure. The crystallite sizes of the CdO nanoparticles were decreased from 20.1 nm to 18.1 nm with the incorporation of the Cr and Sb dopant to the crystal lattice while the crystallite sizes were increased with post annealing. The band gap energies were found to be 5.37 eV and 5.31 eV for CdO:Cr and CdO:Sb nanoparticles which are higher than that of undoped CdO (5.11 eV). The band gap energies of the as-grown nanoparticles were decreased with annealing due to the increasing crystallite size of the synthesis nanoparticles. The transmittance of CdO increased with Cr and Sb doping and showed sharp rise near the band edge. In order to investigate the nonlinear absorption characteristics, the open aperture Z-scan experiments were performed by using 4 ns pulse laser. The absorption coefficeients and saturation intensity threshold increased with doping and decreased with post annealing.

Theoretical and experimental investigation of structural and optical properties of lithium doped cadmium oxide thin films

In this work, undoped CdO and Lithium doped CdO (Li:CdO) with 2% and 6% concentrations thin films were deposited using spray pyrolysis technique. Structural, morphological and optical properties of the deposited films were studied by x-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and UV–vis spectroscopy. The results and the density functional theory (DFT) showed that CdO have cubic structure. The exchange-correlation functions were indicated with generalized gradient approximation (GGA) by DFT. Experimental optical results showed that transmittance was decreased from 79% (undoped CdO) to 30% (CdO doped with 6% Li); and the theoretical results showed that it decreased from 81% (undoped CdO) to 31.55% (CdO doped with 6% Li). Similarly, energy gap (Eg) was decreased from 2.574 eV to 2.367 eV; while for the theoretical results it decreased from 2.611 eV to 2.390 eV with increasing Li doping concentration. Theoretical and experimental data were closely compatible.

Structural, electrical and optical characterization of Mn doped CdO photodiodes

Undoped CdO, 0.2% Mn doped CdO, 6% Mn doped CdO and 10% Mn doped CdO photodiodes were prepared using sol-gel method and deposited on Si substrate at room temperature. Electrical and optical properties of the diodes were assessed, and surface properties were investigated using atomic force microscopy. Atomic force microscopy assessment revealed that undoped and Mn doped CdO thin films were formed in a granular structure where grains composing thin film spread homogeneously on a substrate. To assess the electrical properties current - voltage (I - V), current – time (I - t) graphs were obtained in various illumination intensities; it was seen that diodes show rectifying properties and good photovoltaic behaviour. Photo-characterizations revealed that photodiodes show increasing photocurrent with increasing illumination intensities; the photodiodes also show decreasing capacitance with increasing frequency. Optical properties of the thin films were assessed using UV–vis spectrometry. Bandgap energies were calculated using UV–vis absorption spectra which were found between 2.41 eV and 1.70 eV.

Effect of Mn3O4 on the Dielectric Characteristics of Cdo - Mn3O4 Nanocomposites

Undoped CdO, Mn3O4 and CdO - Mn3O4 doped nanocomposites in the ratio 9:1, 8:2, 7:3 and 6:4 were successfully synthesized through thermal decomposition at high temperature by adopting the method of solid state reaction. powder X-ray diffraction (PXRD) was employed to carry out the structural characterization. It was found that as the concentration of Mn3O4 was increased the size of the prepared CdO-Mn3O4 composites has decreased. The change of various dielectric variables like dielectric loss (tanδ), dielectric constant (εr) was determined. Moreover the change of ac conductivity (σac) with respect to frequency was carried out using LCR meter. It was found that these dielectric parameters have increased with respect to the temperature. It was also found that, with an increase in temperature the dc conductivity measurements for the prepared nano composites have also increased