Influence Of Cr Doping Research Articles

Effect of Cr doping on electronic and optical properties of mono/bilayer MoTe2 nanosheets– a first-principles study

The influence of Cr-doping on mono/bilayer MoTe2 nanostructures is studied within the framework of density functional theory (DFT) since doping may be used to effectively tailor the electronic and optical characteristics in a desired manner. Chromium (Cr) seems to modify the electronic properties and energy band gap of MoTe2 considerably. At first, we confirmed the stability of the proposed structure with the support of cohesive formation energy and phonon-band-spectrum. Moreover, doping with Cr on MoTe2 produces a red shift towards far infra-red region in the absorption coefficient, thus making it suitable for far infra-red region applications. Hence, Cr doping is employed in this work. When Cr impurities are substituted in pristine MoTe2 nanostructures, the band structure gets modified. Additionally, the band gap of mono/bilayer MoTe2 nanostructures reduces from 1.143/0.74 eV for pristine MoTe2 to 0.807/0.621 eV for 8 % substitution of Cr. By examining absorption spectra, it was found that the optical characteristics of mono/bilayer MoTe2 changed significantly with doping of Cr impurities. The results of this study provide insight into the band structure, optical, and electronic attributes of mono/bilayer MoTe2 nanostructures that could be further fine-tuned for optoelectronic applications using substitution of Cr impurities.

Crystallization behavior and structural characteristics of Cr-doped Sb70Se30 thin films for phase change memory

In this study, we prepare Cr-doped Sb70Se30 (SS) thin films via the magnetron sputtering. The influence of Cr doping on the crystallization behavior and structure characteristics of the SS thin films is systematically studied using a combination of experimental analyzes and theoretical calculations. The results reveal that compared with SS thin films, Cr-doped SS thin films exhibit higher crystallization temperature, better data retention capability, larger crystallization activation energy, and reduced resistance drift coefficient. In addition, the incorporation of Cr effectively suppresses grain growth in the SS thin films and refines the grain size. The electrical transport properties of the Cr-doped SS thin films are analyzed using a Hall system. Both X-ray photoelectron spectroscopy and first-principles calculations indicate that Cr is more prone to occupy Sb atoms and form stronger Cr–Se bonds, consequently enhancing the stability of the SS thin films. Raman spectroscopy confirms that the introduction of Cr leads to a decrease in bond length and an increase in bond energy. Moreover, the Cr-doped SS thin film exhibits minimal volume fluctuations and a smoother surface morphology, resulting in enhanced interface performance and reliability. Taken together, these results indicate that the introduction of Cr is an effective strategy for optimizing the properties and modifying the structures of SS phase-change materials.

Epitaxial Growth and Characterization of Nanoscale Magnetic Topological Insulators: Cr-Doped (Bi0.4Sb0.6)2Te3.

The exploration initiated by the discovery of the topological insulator (BixSb1-x)2Te3 has extended to unlock the potential of quantum anomalous Hall effects (QAHEs), marking a revolutionary era for topological quantum devices, low-power electronics, and spintronic applications. In this study, we present the epitaxial growth of Cr-doped (Bi0.4Sb0.6)2Te3 (Cr:BST) thin films via molecular beam epitaxy, incorporating various Cr doping concentrations with varying Cr/Sb ratios (0.025, 0.05, 0.075, and 0.1). High-quality crystalline of the Cr:BST thin films deposited on a c-plane sapphire substrate has been rigorously confirmed through reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM) analyses. The existence of a Cr dopant has been identified with a reduction in the lattice parameter of BST from 30.53 ± 0.05 to 30.06 ± 0.04 Å confirmed by X-ray diffraction, and the valence state of Cr verified by X-ray photoemission (XPS) at binding energies of ~573.1 and ~583.5 eV. Additionally, the influence of Cr doping on lattice vibration was qualitatively examined by Raman spectroscopy, revealing a blue shift in peaks with increased Cr concentration. Surface characteristics, crucial for the functionality of topological insulators, were explored via Atomic Force Microscopy (AFM), illustrating a sevenfold reduction in surface roughness as the Cr concentration increased from 0 to 0.1. The ferromagnetic properties of Cr:BST were examined by a superconducting quantum interference device (SQUID) with a magnetic field applied in out-of-plane and in-plane directions. The Cr:BST samples exhibited a Curie temperature (Tc) above 50 K, accompanied by increased magnetization and coercivity with increasing Cr doping levels. The introduction of the Cr dopant induces a transition from n-type ((Bi0.4Sb0.6)2Te3) to p-type (Cr:(Bi0.4Sb0.6)2Te3) carriers, demonstrating a remarkable suppression of carrier density up to one order of magnitude, concurrently enhancing carrier mobility up to a factor of 5. This pivotal outcome is poised to significantly influence the development of QAHE studies and spintronic applications.

Assessment of Cr doping on TiO2 thin films deposited by a wet chemical method

Undoped and Cr-doped TiO2 thin films were synthesized by the dip-coating sol-gel process with titanium isopropoxide and chromium (III) chloride hexahydrate being used as the precursors. The chromium concentrations changed for different molar ratios, namely, 2, 4, and 8 wt.%. The samples, coated on glass substrates, were later annealed in air at 450 °C for 60 min. The influence of Cr doping on the structural, surface chemical, and optical properties of the samples was studied by several techniques, including EDS, Raman, UV–Vis, RT-PL, and XPS spectroscopies, as well as SEM and XRD. The diffraction patterns indicated that all the films displayed the anatase structure with the crystallite size decreasing with chromium doping. The same structure was confirmed by Raman spectroscopy measurements. UV–Vis absorption spectra of the samples showed a red shift of the fundamental absorption edge in the visible range following the increase of Cr doping concentration. In addition, the RT-PL study revealed that the dopant incorporation causes a decrease in the PL intensity. The EDS analysis revealed the presence of Ti, O, and Cr in the materials. Moreover, from high-resolution XPS Ti 2p spectra, titanium was found to be in the Ti4+ oxidation state evidencing the formation of TiO2, while the Cr 2p fitting analysis showed that chromium is present in the Cr (III) and Cr-metal states.

Effect of Cr-Doping on the Structural and Magnetic Properties of Mechanically Alloyed FeCoNiAlMn1-xCrx High-Entropy Alloy Powder.

In this work, the new compositions of FeCoNiAlMn1-xCrx, (0.0 ≤ x ≤ 1.0), a high-entropy alloy powder (HEAP), are prepared by mechanical alloying (MA). The influence of Cr doping on the phase structure, microstructure, and magnetic properties is thoroughly investigated through X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometry. It is found that this alloy has formed a simple body-centered cubic structure with a minute face-centered cubic structure for Mn to Cr replacement with heat treatment. The lattice parameter, average crystallite size, and grain size decrease by replacing Cr with Mn. The SEM analysis of FeCoNiAlMn showed no grain boundary formation, depicting a single-phase microstructure after MA, similar to XRD. The saturation magnetization first increases (68 emu/g) up to x = 0.6 and then decreases with complete substitution of Cr. Magnetic properties are related to crystallite size. FeCoNiAlMn0.4Cr0.6 HEAP has shown optimum results with better saturation magnetization and coercivity as a soft magnet.

Influence of Cr doping on the structural, optical, and third-order nonlinear optical properties of ZnAl2O4 nanoceramics

In this research, Zn(1−x)CrxAl2O4 (x = 0.00, 0.05, 0.10, 0.20) nanoparticles were prepared by a simple and green chemistry synthesis using gelatin as a polymerization agent. X-ray diffraction technique and scanning electron microscopy imaging were used to analyze the structural and morphological properties of the samples. X-ray diffraction results revealed that all samples were polycrystalline and crystallized in a cubical spinel phase. With increasing the x from 0.00 to 0.20, the main Bragg peaks shift to smaller angles, and the crystallite size and energy bandgap of samples decrease as well. The nonlinear absorption coefficient, β, and nonlinear refractive index, n2, of Zn(1−x)CrxAl2O4 were meticulously studied by the Z-scan approach. The orders of n2 and β are 10−7 and 10−4 cm/W, respectively. The saturable absorption and the self-defocusing effect are the main factors in the appearance of β and n2, respectively. The experimental results confirmed that increasing the percentage of Cr caused nonlinear coefficients to increase.

Influence of Cr Doping on Structural, Optical, and Photovoltaic Properties of BiFeO3 Synthesized by Sol-Gel Method

In this work, pure BiFeO3 and samples doped with different concentrations of chromium were synthesized to improve the optical properties and efficiency of solar cells based on BiFeO3. The sol-gel method was used for synthesis due to its ability to produce nanostructured materials with high purity and good homogeneity, as well as the possibility of controlling the size and shape of the resulting particles. The samples were characterized by different analytical techniques. Thermal analysis results indicate that the dopant increases the weight loss of the sample from 61 to 81%, with an increase in the exothermal in the nucleation and crystallization temperature range. The X-ray diffraction patterns and UV-visible spectra show a dependence of the crystallite size and bandgap with respect to the amount of Cr dopant, decreasing from 168 to 73 nm and from 2.14 to 1.92 eV, respectively. Scanning electron microscopy images display a decreasing grain size as a result of an increasing amount of dopant. The I-V analysis results show a 1% Cr-doped BiFeO3 photovoltaic device exhibits enhanced photovoltaic performance with higher photocurrent and 4.17 times greater energy conversion efficiency compared with a pure BiFeO3 photovoltaic device. For their behavior, Cr-doped BiFeO3-based photoelectrodes are very promising materials for photovoltaic devices.

Tuning of magnetic properties in Cr-doped lithium ferrite

Cationic substitutions in lithium ferrite spinel (LiFe 5 O 8 ) leading to modifications in magnetic properties have a significant role in their technological applications. In this context, LiFe 5− x Cr x O 8 , compounds with 0 ≤ x ≤ 3 were synthesized and studied using X-ray diffraction, X-ray photoelectron spectroscopy (XPS), M o ¨ ssbauer spectroscopy and magnetization measurements. Oxidation states of Fe and Cr are found to be 3 + from XPS investigations and further confirmed from the M o ¨ ssbauer analysis. Cr replaces Fe from both tetrahedral and octahedral sites. Magnetization and magnetic ordering temperature decrease with increasing Cr concentration. This is consequent to reduced strength of dominant Fe - O - Fe interactions due to replacement of Fe with Cr cation possessing relatively smaller magnetic moment. The positive value of Curie-Weiss constant implies that the system has dominant ferromagnetic interactions. The much important negative magnetization and spin compensation phenomena are observed only in specific range of doping concentration (x = 2.5–3). Spin compensation in LiFe 2.5 Cr 2.5 O 8 occurs at 315 K, close to room temperature. • The effect of Cr doping on oxidation state of cations and their distribution at tetrahedral and octahedral sites is reported. • The influence of Cr doping on the magnetic properties of LiFe 5 O 8 is reported. • Spin compensation behavior is observed in LiFe 2.5 CR 2.5 O 8 and LiFe 2 CR 3 O 8 compounds.

Influence of Cr-doping on structural, magnetic and dielectric properties of M-type hexaferrites synthesized using microwave digestion technique

M-type hexaferrite SrCrxFe12-xO19 compounds doped with Cr (x = 0, 1, 2, 3 and 4 at.%) were prepared by microwave digestion system. X-ray diffraction was used to study the structure and crystallization of the samples. The samples are found to have a hexagonal phase, SrFe12O19, as a main phase at 2θ ≈ 33.144° and 35.618° for x = 0 and 1 respectively, and 32.451° and 34.295° for x ≥ 2. The Rietveld refined parameters such as the lattice parameters (a = b, c), direct and indirect cell volume, crystallite size and microstrain were investigated. TEM and SEM results showed that the samples have hexagonal shape and grain size range from 126 nm to 379 nm. Magnetization, M, as a function of the applied magnetic field, H, was obtained from the hysteresis loop. The coercive field, H C , saturation, M s and remnant, M r , magnetization and squareness ration, M r /M s , were extracted from the hysteresis loop results. These results revealed that H C is inversely proportional with the grains size of the samples but directly proportional with Cr-doping values candidating these compounds to be used in computer hard disk memories applications. M values are inversely proportional with Cr-doping values. The variation of conductivity, σ, impedance, Z, dielectric constant, ε, dielectric loss factor, tan δ and dissipation factor as functions of both AC frequency, F(Hz) and Cr-doping, x, were investigated. The maximum value of the dissipation factor was at x = 2 which equals 8.05 × 109 m F−1 when F = 2 × 105 Hz. The impedance of the samples behaved as a capacitor reactance that makes our compounds candidate for many crucial dielectric applications.

Structural and thermal properties of pure and chromium doped zinc oxide nanoparticles

Pure ZnO and Cr-doped ZnO nanoparticles have been synthesized via a facile chemical co-precipitation route and their structural, thermal characteristics were discussed systematically. In the experimental producer, the doping concentration has varied the range, 0.05–0.1 M, while calcined at 600 °C. The influence of Cr-doping on the physical characteristics of ZnO nanoparticles was investigated and addressed. As-prepared samples were analyzed via XRD, FTIR, TGA/DTA, BET, and ICP-MS. XRD analysis shows that ZnO and Cr doped ZnO nanoparticles with average particle sizes between 23 and 39 nm were successfully developed with hexagonal wurtzite structure. The FTIR spectroscopy analysis confirms the existence of chromium in the doped ZnO nanoparticles and the formation of ZnO. The TGA/DTA analysis shows that Cr–ZnO nanoparticles are more thermally stable than ZnO nanoparticles. Moreover, the dopant concentration has been analyzed via ICP-MS and showed a good agreement with the expected chromium concentration. The BET surface area measurement shows that 176.25 m2/g and 287.17 m2/g for un-doped ZnO, and 0.1 M Cr-doped ZnO nanoparticles, respectively. Hence, doping of Cr enhances the surface area and thermal stability. Thus, Cr–ZnO nanoparticles show good thermal stability, and high surface area, which is an excellent characteristices of nanomaterials.Graphic abstract

Influence of Cr-doping on the formation, martensitic transformation and magnetic properties of Mn2NiGa1-xCrx (x = 0–0.5) ribbon samples

Mn2NiGa1-xCrx (x = 0–0.5) alloys were synthesized successfully to explore possible Cr-based all-d-metal Heusler alloys with magnetic shape memory effects. When x = 0–0.25, Mn2NiGa1-xCrx are single BCC Heusler phase, but when x = 0.375 some FCC phase co-exists with the main Heusler phase, finally a pure FCC phase is formed in Mn2NiGa0.5Cr0.5. In BCC Mn2NiGa1-xCrx, Cr-doping leads to the decrease of martensitic transformation temperature TM and increase of the saturation magnetization Ms at 5 K. While the FCC phase does not show the trace of phase transition and has a very low magnetization till 5 K. First-principles calculations suggest that, in BCC Mn2NiGa1-xCrx the partial spin moment of Cr is large and parallel to that of Mn (B), which leads to the increase of Ms when x = 0–0.25. A higher stability of the martensite than the austenite is found, which supports the phase transition observed experimentally. It may be noticed that the TM of Mn2NiGa1-xCrx decreases with both increasing e/a and decreasing cell volume, which is opposite to the empirical rule in traditional Heusler alloys. Calculation suggests that Cr–Ga disorder may be a possible reason for this decrease.

Influence of Cr doping on the structural, optical, magnetic, and photoluminescence behavior of Zn0.96−xNi0.04CrxO nanostructures

Ni, Cr, co-doped ZnO nanostructures with different Cr concentrations from 0 to 4% have been synthesized using sol–gel route. Hexagonal structure of ZnO and phase purity were confirmed by X-ray diffraction (XRD) patterns. Cr doping into Zn–Ni–O could not alter the hexagonal structure. The steady decrease of crystallite size by Cr substitution revealed the proper substitution of Cr3+ instead of Zn2+ in ZnO lattice with dissimilar ionic radii. The diminishing energy gap by Cr addition is due to the s–d and p–d exchange interactions among the localized d electrons of the Cr ions. The presence of Cr in Zn–Ni–O lattice was confirmed by Fourier transform infra-red (FTIR) analysis through structural bonding. The significant modulation in photoluminescence (PL) intensity, position of different PL bands, and the increase of PL emissions by Cr doping is discussed based on electron concentration, zinc interstitial, and zinc vacancies. Room temperature ferromagnetic (RTFM) nature in the derived samples is the collective consequence of intrinsic defects and exchange interaction and not by any other magnetic or Ni/Cr oxide phases.

Influence of Cr doping on hydrogen permeation performance of lanthanum tungstate membrane

A series of La5.5W1-xCrxO11.25-δ (LWCrx, x = 0.1, 0.2, 0.3 and 0.4) powders were successfully synthesized by a traditional solid-state reaction method. The influences of Cr doping on phase structure, microstructure, hydrogen permeation and chemical stability of lanthanum tungstate were investigated in details. The oxygen vacancy concentration in LWCr0.2 was higher than the other three samples. Moreover, the hydrogen permeation fluxes through LWCrx membranes increased with the increase of Cr content when x ≤ 0.2, and LWCr0.2 exhibited the highest hydrogen permeation flux because of its higher oxygen vacancy concentration. Besides, the hydrogen permeation fluxes through LWCr0.2 membrane were comparable to that through La5.5W0.8Mo0.2O11.25-δ (LWMo0.2) membrane. During a 104 h of hydrogen permeation test, the hydrogen permeation flux and phase structure changed slightly, revealing a good stability of LWCr0.2 membrane.

Enhanced UV photodetection behavior of Cr doped wurtzite ZnO crystalline nanorods

Abstract The influence of Cr doping on optical, morphological and electron transport properties of ZnO nanorods were studied. High crystalline wurtzite ZnO nanorods were prepared by the reflux method and the structural properties were studied from X-Ray diffraction (XRD) pattern. Morphological analysis was done by field emission scanning electron microscopy (FESEM), transmission electron microscopy (HRTEM). The FESEM and HRTEM results show the size reduction from micrometer to nanometer regime with the addition of Cr doping. The optical properties were studied from absorption spectra. The enhancement in absorption band with the addition of Cr doping is observed. The enhancement of NBE and Green emission of ZnO with the addition of Cr doping was analyzed from fluorescence spectra. The electronic state of Zn, O was confirmed from X-Ray photoelectron spectroscopy. The additional peak around 570–590 eV confirms the chromium doping in the Zn sites. The enhancement in photoconductivity of ZnO nanorods with the addition of Cr doping is observed from the IV measurements.

Effect of Chromium on electrochemical and mechanical properties of beta-Al2O3 solid electrolyte

In order to improve the performance of the beta-Al2O3 solid electrolyte, the influence of Cr doping during the preparation of Na-beta-Al2O3 by solid state method was studied, the α-Al2O3 and Na2C2O4 was used as raw materials, and Li+ was added to stabilize β″ phase. The results showed that without Cr2O3 doping, the β″ phase content of the electrolyte was 92.28%, and the relative density was 99.07% of the theoretical density. The appropriate amount of Cr element could stabilize the β″ phase and refine the grain, when the doping amount of Cr2O3 was 0.15 wt%, the content of β″ phase could reach 97.93%, the relative density was 99.07%, the ionic conductivity was 0.082 S · cm−1 at 350 °C, and the bending strength was 253 Mpa. In addition, the excessive Cr element tends to gather in the grain boundary, resulting in the melting state and non-uniform size of the grains, and it will also hinder the formation of the β″ phase.

Influence of Cr doping on the structural, magnetic, optical and photocatalytic properties of α-Fe2O3 nanorods

Pure and Cr-doped hematite (α-(Fe1-xCrx)2O3, x = 0, 0.026, 0.039, 0.085 or 0.135) nanorods were prepared by a simple co-precipitation and calcination method. Influence of different levels of Cr doping on the change of properties of long and thin pure hematite nanorods was investigated. Cr3+-for-Fe3+ substitution in the crystal structure of hematite was proved by measuring a gradual contraction of the unit cell and a gradual decrease of the hyperfine magnetic field by increasing the Cr molar fraction. Cr doping induced an increase in the width and thickness of hematite nanorods, as well as a decrease in the overall surface area. Low temperature 57Fe Mössbauer spectroscopy showed that the Morin transition in hematite was suppressed by Cr doping to temperatures below 80 K. Magnetic measurements confirmed the suppression of the Morin transition in Cr-doped hematite down to 5 K. Infrared spectra of Cr-doped hematite samples showed shifts of IR bands by Cr3+-for-Fe3+ substitution. Optical properties of α-Fe2O3 nanorods changed significantly by Cr doping – the absorption edge was shifted to higher wavelengths, accompanied by a greater absorption in the visible range and narrowed direct and indirect optical band gaps. The improved visible light photocatalytic activity of hematite nanorods in the heterogeneous photo-Fenton process by moderate Cr doping was measured, which can be attributed to the modifications in electronic structure and optical properties.

Synthesis and Performance of Cr Doped Li3V2(PO4)3/C Cathode Materials for Li Ion Batteries

A series of Cr-doped Li3V2-xCrx(PO4)3/C (x = 0.00, 0.10, 0.15, 0.20) composites was synthesized using Sol-gel method. The influence of Cr doping on the structure, morphology and electrochemical performance of Li3V2(PO4)3/C were studied. The X-ray diffraction patterns indicate that all of the samples are consistent with those of monoclinic Li3V2(PO4)3, indicating that Cr3+ can be successfully doped into the lattice of Li3V2(PO4)3. Scanning electron microscopy, transmission electron microscopy mages revealed the morphology and the uniform distribution of Cr in the samples. In the potential range of 3.0–4.3 V, the Li3V1.9Cr0.1(PO4)3/C composite exhibited the highest discharge capacity of 125.1 mAh/g at 0.1 C, while the Li3V1.8Cr0.2(PO4)3/C performed a capacity of 95.8 mAhg−1 with a high capacity retention ratio of 91.6% after 40 circles, which is still lower than the capacity of the Li3V1.9Cr0.1(PO4)3/C. Based on the excellent electrochemical performance, Li3V1.9Cr0.1(PO4)3/C will be a promising cathode material for rechargeable lithium-ion batteries.

The Influence of Cr doping on the Structural and Magnetic Properties of HoMnO3 Multiferroic Ceramics

In this research single-phase Cr-doped HoMnO3 ceramics were synthesized via solid state reaction method. The structural and magnetic characteristics of the prepared samples were examined using various characterization techniques, including x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and vibrating sample magnetometer (VSM). All samples exhibit single phase that emphasized by SEM and XRD. Magnetic properties of the prepared samples at low temperature (10K) showed the presence of different magnetic characteristics. The change in magnetic behavior could probably occur due to slight decrease in the unit cell volume that leads to a structural distortion in the lattice. Cr-doped HoMnO3 could be a good candidate with a better ferromagnetic property for practical multiferroic applications.

Structural, optical and gas sensing properties of Cu2O/CuO mixed phase: effect of the number of coated layers and (Cr + S) co-Doping

ABSTRACTThin films of Cu2O/CuO mixed phase have been deposited on pre-cleaned glass substrate by a spin-coating technique. The influence of Cr-doping, (Cr + S) co-doping and the number of coated layers on the structures and optical behaviors of the films were investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman, and UV-Visible spectroscopies. From XRD, FTIR and Raman results; the films are composed of polycrystalline monoclinic CuO and cubic Cu2O phases with crystallite sizes ranged from 10.05 to 23.08 nm. Increasing the thickness improves the films’ crystallinity and decreases the defects level in the films. Cr and S incorporation encourages the growth of CuO phase at the expense of Cu2O one and affects the preferred growth direction. The doping with Cr and S blue shifted the Bg mode and multi-phonon transitions. The direct and indirect optical band gaps decreased from 2.25 eV and 1.60 eV to 2.10 eV and 1.20 eV by growing the number of deposited layers from 2 to 8 layers. The film sensitivity towards CO2 at different gas flow rate was studied and compared with those of similar systems. Also; response time, recovery time, detection limit, and limit of quantification are estimated.

Influence of Cr doping on Schottky barrier height and visible light detection of ZnO thin films deposited by magnetron sputtering

Abstract A comparative study of the electrical and photodetection properties of ZnO and Cr doped ZnO thin films are being reported here. The films were deposited using magnetron sputtering. X-ray diffraction (XRD) revealed hexagonal crystal structure of the films with (002) preferred orientation. Pt/ZnO/Pt and Pt/Cr doped ZnO/Pt Schottky diodes were fabricated for photodetection studies. The Schottky barrier height was lowered for Cr doped ZnO film as compared to ZnO film. The ideality factor was improved upon Cr doping. Pt/ZnO/Pt diode was unresponsive to visible light, however, Pt/Cr doped ZnO/Pt diode showed response to visible light with short response and recovery times. The response of the Pt/Cr doped ZnO/Pt diodes to visible light is attributed to the reduction in band gap of the Cr doped ZnO thin film.