DC Magnetron Sputtering System Research Articles

Study on the process of hydrogen-doped indium oxide for silicon heterojunction solar cell mass production

In this work, we conducted a comparative study on water vapor (H2O) process and hydrogen gas (H2) process to prepare the IMO:H films based on industrialized DC magnetron sputtering system. To dynamically control the residual H2O pressure, we installed a set of polycold coil and kept it turned on during the sputtering process. The film characteristics of Hall mobility, carrier density, sheet resistance, and transparency was investigated. The results revealed that the silicon heterojunction (SHJ) solar cell with H2 process had a higher Hall mobility and greater transparency in the 400–600 nm wavelength range resulting in a lower contact resistivity and a slight increase current density compared to the H2O process. The median efficiency (Eff) achieved with the H2 process improved by 0.09% absolute to 25.43%, mainly because of the increased Jsc and FF. And the IMO:H films with H2 process had a large basal spacing with (400) and (222) crystal planes resulting in maintaining a more stable and reliable structure at temperatures below 200 °C. After the optimization of TCO layer process, we manufactured the industrial-grade SHJ cells with max efficiency (Eff), Voc, Jsc, and fill factor (FF) values as high as 26.27%, 753 mV, 41 mA/cm2, and 86%, respectively. The IMO:H films with H2 process can thus be considered more suitable for large-scale production.

Influence of surface roughness on magnetic property of magnetron sputter deposited FePtCo films

ABSTRACT Thin films of FePtCo ternary alloy with 100 nm thickness have been deposited on an Si substrate using a DC magnetron sputtering system by co-sputtering of Co metal target and Fe40Pt60 alloy target in three different conditions, i.e. as-deposited at room temperature, annealed at 400 °C ∘ C , and deposited on the seed- layer. The effects of target sputtering power, leading to different compositions and various deposition conditions on surface roughness of films and magnetic properties, were studied. The average surface roughness of the as-deposited films decreases with the increase in the sputtering power of the Co target. For the annealed and seed-layered films, an increase in Co sputtering power resulted in an increased in roughness. Moreover, the annealed films possess smallerlower roughness due to an increase in the surface mobility. On the other hand, the Cu seed- layer decreases the roughness by preventing the diffusion of the film into the substrate. The room -temperature M-H measurement shows that the films exhibit soft ferromagnetism with coercivity in the order of 10 3 A/m and large saturation magnetizationmagnetisation of the order 10 6 A/m. The saturation magnetizationmagnetisation decreases with the increase in the sputtering power and is not influenced by the film surface roughness. On the other hand, riseincrease in surface roughness leads to decrease in coercivity of the films.

Tribocorrosion behaviors of VNbMoTaWCr high entropy alloy coatings

In this work, four BCC-structured VNbMoTaW and VNbMoTaWCr high entropy alloy (HEA) coatings with different Cr contents were fabricated on the surface of 304 stainless steel (304SS) plates by a pulsed DC magnetron sputtering system. In addition to the dry pin-on-disk wear test and pure corrosion test, two kinds of tribocorrosion tests were performed. For the tribocorrosion test without applied potential, the HEA coatings were immersed in a 3.5 wt% NaCl aqueous solution at room temperature under 1 N load using a pin-on-disk tribometer. For the tribocorrosion test with applied potentials, the potentiodynamic polarization test was conducted to investigate the effects of external potentials and sliding loads on the corrosion current density, polarization resistance, and wear rates of HEA coatings. The hardness, corrosion resistance, and tribocorrosion (without applied potential) resistance of VNbMoTaWCr HEA coatings increased with increasing Cr content. The VNbMoTaWCr coatings with higher than 24.7 at.% Cr had a high hardness of 16.4 to 16.5 GPa and excellent corrosion resistance in pure corrosion and tribocorrosion without applied potential. On the other hand, as the tribocorrosion was executed with an applied potential higher than the breakdown potential and high current density, the tribocorrosion resistance of HEA coatings was greatly influenced by its protection degradation ratio, Pdr (the polarization resistance ratio between pure corrosion and tribocorrosion setup 2). Finally, the lowest wear rate of 2.55 × 10−5 mm3N−1 m−1, which was 1.4 times better than 304SS, was obtained for the VNbMoTaWCr coating containing 11.65 at.% Cr after the tribocorrosion test with applied high potential because of its lower Pdr value and less decay of corrosion protection ability.

Influence of Ag on the microstructure, mechanical and tribological properties of SiC–Ag composite film deposited by the industrial DC magnetron sputtering system

Industrial synthesis and application of green self-lubricant hard film have been considering as a hot spot in the field of surface engineering. In this paper, the Ag was added into the amorphous SiC matrix to deposit a series of Ag–SiC composite film with various Ag content using an industrial DC magnetron sputtering system, to enhancing the tribological properties for the real self-lubricant applications. Results showed that a dual-phase of fcc-Ag and amorphous SiC co-existed into the films regardless of Ag content. The accumulation of nano-particles of Ag could be detected in the amorphous matrix. The addition of soft Ag into the matrix gradually decreased the hardness from 21 ± 1 GPa for the binary SiC film to 7 ± 1 GPa for the composite film at 15.3 ± 0.8 at.% Ag, whilst it also dropped room temperature the average friction coefficient. Both the enhanced anti-friction property and the degradation of hardness attributed to the wear rate first dropping and then rising as a function of increase of Ag content and the lowest wear rate could be detected for the film at 4.3 ± 0.2 at.% Ag.

Improving the electrochemical corrosion behavior of stainless steel (316L) through the deposition of tantalum-based thin films

Austenitic 316L stainless steel (SS) is commonly used as a biomaterial for human implant applications. However, its clinical uses are limited due to its relatively high corrosion rate in physiological conditions. Various surface modifications, including coatings, have been developed to enhance its performance. In this study, a thin layer of Tantalum (Ta) was applied to the surface of 316L stainless steel using a DC Magnetron Sputtering (DCMS) system; the thickness of the coating varied from 1.504 to 6.083 µm, achieved by deposition times ranging from 15 to 60 min. The aim was to examine the electrochemical corrosion characteristics of the uncoated 316L SS and the Ta-coated 316L SS, followed by Potentiodynamic Polarization (PDP), Electrochemical Impedance Spectroscopy, and Open Circuit Potential tests. These tests were conducted for 10 min, 60 min, and 90 min to assess their performance over time. The PDP measurements took place in a simulated body fluid (SBF) at a pH of 7.8 ± 0.25 and a temperature of 40 °C, with varying coating durations. The PDP test outcomes revealed that the Ta-coated 316L stainless steel exhibited enhanced resistance to corrosion compared to the uncoated 316L stainless steel sample. The efficacy of Ta coatings on the 316L stainless steel samples was assessed through several techniques, including Optical microscopes, Energy Dispersive X-ray Spectroscopy, Scanning Electron Microscopy, and X-ray Photoelectron Spectroscopy. The findings from SEM and EDS verified the successful application of the Ta coating onto the stainless steel. The composition of the surface oxide film of Ta, the substrate, and the thickness of the coating were determined using the XPS technique, which confirms the effectiveness of the Ta coating in safeguarding 316L stainless steel against electrochemical corrosion, particularly for biomedical applications.

Preparation of MoS2 Nanospheres using a Hydrothermal Method and Their Application as Ammonia Gas Sensors Based on Delay Line Surface Acoustic Wave Devices.

An ammonia sensor based on a delay-line surface acoustic wave (SAW) device is developed in this study by coating the delay line area of the device with a nano-structured molybdenum disulfide (MoS2) sensitive material. A SAW device of 122 MHz was designed and fabricated with a pair of interdigital transducers (IDTs) defined on a 128° y-cut LiNbO3 substrate using photolithography technologies, and the aluminum IDT electrodes were deposited by a DC magnetron sputtering system. By adjusting the pH values of precursor solutions, molybdenum disulfide (MoS2) nanospheres were prepared with various structures using a hydrothermal method. Finally, an NH3 gas sensor with high sensitivity of 4878 Hz/ppm, operating at room temperature, was successfully obtained. The excellent sensitivity performance may be due to the efficient adsorption of NH3 gas molecules on the surfaces of the nanoflower-like MoS2, which has a larger specific surface area and provides more active sites, and results in a larger change in the resonant frequency of the device due to the mass loading effect.

Enhanced emission from hBN in sputtered microcavities.

In this observational study, we embed few-layer hexagonal boron nitride (hBN) inside a planar Fabry-Perot cavity fabricated using a pulsed DC magnetron sputtering system and show that the hBN retains its inherent visible range, defect-based luminescent properties following relatively energetic deposition processing. The observed surface-normal emission enhancement factor of ∼40 is in good agreement with theoretical predictions. We also found that embedded hBN subjected to a rapid thermal annealing treatment exhibits a cracking effect where the edges of the material glow distinctly brighter than adjacent regions. Our results might inform future efforts involving monolithic integration of hBN active layers.

Effects of Ag-doped Content on Antimicrobial Activity and Substrate Color of Chromium Thin Films Deposited by DC Magnetron Sputtering

Silver ions (Ag+) show promise as excellent antimicrobial agents to inhibit microbial growth on high-touch surfaces. In this study, Ag-doped Cr films were deposited using a DC magnetron sputtering system from a mosaic target. The Cr-Ag mosaic target was a 0.125-inch-thick Cr base (99.95% pure) with different diameters of Ag circle sheets mounted on the Cr target. The sputtering condition was kept at a DC power of 100W, working pressure of 8.3x10-3 mbar with Ar as the sputtering gas, and sputtering times of 15 and 30 min. The antimicrobial activity and efficiency were determined by standard testing (JIS Z 2801: 2000). The antibacterial performance was calculated from the antibacterial inhibition of the Ag-doped Cr films in bacterial solution (Staphylococcus aureus and Escherichia coli) after 24 h. The results showed that the Ag content was between 0.27 at% and 6.11 at% depending on the diameter of Ag and the deposition time. The minimum Ag content of 4.05 at% had an inhibition efficiency of 99.98% (E. coli) and 96.33% (S. aureus). The contact angle testing of Ag-doped Cr films showed hydrophobic behavior with the angle greater than 90 degrees. The optical color of the Ag-doped films was characterized by UV-vis spectroscopy (CIE testing). The film colors were significantly changed by the addition of Ag into the Cr films. The total color difference (DE) increased by 3-10 units compared to the reference chromium film and the Ag doping mainly affected +L* (Lightness). Keywords: sputtering PVD; antibacterial agent; silver; mosaic target; ROS; gram-negative; gram-positive; CIE-L*ab *Corresponding author: Tel.: (+66)934598942 E-mail: 62609006@kmitl.ac.th

Study of morphological, physical and mechanical properties of thin NbN films synthesized via DC magnetron sputtering system

PurposeNiobium Nitride (NbN) was interesting material for its applications in the medicinal tools or tools field (corresponding to saline serum media) as well as in mechanical properties. The aim of this work was depositing NbN thin films on two types of substrates (stainless steel (SS304) and silicon (100)) using plasma technique at varied powers (100–150 W).Design/methodology/approachDC magnetron sputtering technique at different powers were used to synthesis NbN films. Film structure was studied using X-ray diffraction (XRD) pattern. Rutherford elastic backscattering and energy dispersive X-ray were used to examine the deposited film composition. The films morphology was studied via atomic force microscopy and scanning electron microscopy images. Corrosion resistance of the three NbN/SS304 films was studied in 0.9% NaCl environment (physiological standard saline).FindingsAll properties could be controlled by the modification of DC power, where the crystallinity of samples was changed and consequently the corrosion and microhardness were modified, which correlated with the power. NbN film deposited at higher power (150 W) has shown better corrosion resistance (0.9% NaCl), which had smaller grain size (smoother) and was thicker.Originality/valueThe NbN films have a preferred orientation (111) matching to cubic structure phase. Corrosion resistance was enhanced for the NbN films compared to SS304 substrates (noncoating). Therefore, NbN films deposited on SS304 substrate could be applied as medicinal tools as well as in mechanical fields.

High temperature friction and galling properties of nanolayered (Cr,V)N coatings and effect of V content

Chromium nitride (CrN) coating is considered as one of the best candidates for wear protection in many forming application where adhesive wear and galling dominate. However, its relatively high coefficient of friction against soft metals hinders its applicability. Vanadium nitride (VN), on the other hand has attracted increasing interest as VN is easily oxidized to form Magneli phase vanadium oxides with easy slipping shear planes, on one hand leading to self-lubricating properties but also to deteriorated wear resistance. This can be overcome by forming CrVN coatings. However, there is a lack of information how such coatings perform in terms of galling resistance and V-concentration in typical forming conditions and against soft metals.Therefore, the aim of this work was to study friction properties of nano-layered PVD (Cr,V)N coatings at room and elevated temperature and how V-content influences on friction and galling resistance against typical work materials. Nanolayered (Cr,V)N coatings with V in concentrations from 15 to 30 % were deposited by industrial DC magnetron sputtering system and tested using Load-Scanner against AA2024 aluminum alloy and low-carbon steel at room and elevated temperature of 300 °C and 600 °C, respectively. Results were evaluated in terms of coefficient of friction level and stability, critical loads for galling initiation and volume of adhered work material. Results show that (Cr,V)N coatings do not necessarily improve galling resistance, being strongly dependent on V concentration and contact temperature. For forming Al alloys positive results are obtained with coatings containing 20–25 at.% V and for low-carbon steels above 25 at.%, with marked improvement obtained only at elevated temperatures.

Improvement on Plasma Intensity Uniformity in Rectangular DC Magnetron Sputter by Optimizing Structures of Substrate Electrode

DC magnetron sputtering is widely used for thin film deposition in the field of displays. By adding magnet arrays to a large rectangular magnetron sputtering system, while the ionization and deposition rate are increased, the film properties can be nonuniform, and the local target erosion rate can be increased. Film properties strongly depend on uniform plasma density and energy. Although the ferromagnetic shield has been used to decrease the magnetic field locally, the plasma remains nonuniform at the corners of the rectangular shape target. In this study, a plasma simulation was conducted to analyze the plasma distribution in a DC magnetron sputtering system. The plasma uniformity was improved by optimizing the thickness and shape of the substrate electrode, carefully controlling the distance between the target and substrate electrode based on Paschen’s law, leading to the reduction of local high plasma intensity.

Crystallinity Study of Cu Thin Film Deposited by Indigenously Developed DC Magnetron Sputtering Setup

AbstractThe copper thin films have a huge application in the field of material science research and they also act as a catalytic substrate which helps to deposit various carbon‐based polymers that can be used for sensors. There are several thin film development techniques available in the industries out of which magnetron sputtering technique shows some remarkable properties essential for depositing metal thin film efficiently. The main objective of this work is to develop copper thin films utilizing an indigenously designed and developed DC magnetron sputtering system. The X‐ray diffraction (XRD) pattern of the developed thin films display prominent peaks of copper (111) plane along with cuprous oxide (110), (111), and (220), respectively. This work also aims to study in detail the crystallinity of the deposited copper thin films by analyzing the XRD results for optimization.

Effect of N doping on the microstructure and dry etch properties of amorphous carbon deposited with a DC sputtering system.

The importance of developing a hardmask with excellent performance, and physical and chemical properties to utilize in long-term etching is spotlighted due to the acceleration of development in high-density semiconductors. To develop such a hardmask, amorphous carbon hardmasks doped with various concentrations of N were fabricated with a DC magnetron sputtering system using varying inert gas (Ar to N2) ratios. In contrast to the expectation that doped nitrogen would block the permeation of fluorine and improve the etch resistance, as the nitrogen concentration increased, the selectivity of the doped amorphous carbon films decreased. To understand this degradation with increasing nitrogen concentration, systematic X-ray photoelectron spectroscopy (XPS), radial distribution function (RDF), and X-ray reflectometry (XRR) analyses were conducted. In this study, we found that as the amount of nitrogen increased, the density of the film decreased, and the amount of pyridinic and pyrrolic nitrogen bonds with low formation energy increased. In contrast, based on time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis of etched nitrogen-doped amorphous carbon films, the penetration depth of fluorine ions from the etchant decreased as the amount of nitrogen increased. Therefore, in order to develop an excellent hardmask using amorphous carbon, it is important to increase the density of the film and the nitrogen concentration in the film while lowering the ratio of pyrrolic N to pyridinic N, i.e., increasing the ratio of graphitic N.

Spin blocking effect at Ni/Pt heterojunction

Spin current, the flow of spin angular momentum, can carry and transport energy and/or information without generating Joule heating, which makes spin-based devices become one of the potential aspects for the next-generation information processing devices. It is important to investigate the generation, transport, and detection of spins for developing spin-based devices, in which the spin transport and its related phenomena attract ongoing interest due to the complex interactions between spins and condensed matter system. Here, spin transport phenomenon is studied at a heterojunction consisting of ferromagnetic metal nickel and nonmagnetic heavy metal platinum, where transport spins are found to be totally blocked. Two series of spin-pumping devices, i.e. the yttrium iron garnet (YIG)/Ni/Pt trilayer devices and the contrastive YIG/Ni bilayer devices, are made in this work. The YIG serves as a substrate and spin-pump layer, on which nickel film and platinum film are deposited by a dc magnetron sputtering system. Spin currents are generated from YIG and injected into nickel layers by spin pumping technology. The voltage signals corresponding to the inverse spin Hall effect are detected and analyzed comparatively for both YIG/Ni/Pt trilayer device and YIG/Ni bilayer device. It is found that the platinum layers in YIG/Ni/Pt trilayer devices act only as charge current shunting but do not contribute to the spin-charge conversion. This implies that the spin current cannot transport through the Ni/Pt interface even when the nickel layer is as thin as 1 nm, in other words, the spin current is blocked at the Ni/Pt interface. Our result proposes a heterojunction that can block transport spins totally, which has never been discussed before, and the present study may expand the views and promote the development of spin-based devices.

Optical and fractal properties of sputter deposited TiO2 films

In this study, TiO2 films were deposited on the glass substrates at different pressures using a DC magnetron sputtering system. The surface topography, fractality, particle size, transparency spectra, and roughness of the deposited films were analyzed through atomic force microscopy in non-contact mode and spectrophotometer (UV–visible) analysis. The Gwyddion open source software was used to analyze the AFM results. The surface morphology, absorption spectra, transparency, and energy band gap of the films were studied through analytical and mathematical relations, including fractal and multifractal dimensions of the films. The pressure influenced the particle size leading to the changes in the surface roughness and fractality of the films. When the working pressure increased above 8 × 10−3 Torr, the nonuniformity in the distribution of surface properties and multifractality increased. Additionally, using optical data and the Tauc’s method, their energy gap was calculated. It was revealed that the TiO2 coatings have a relatively large energy gap of ~ 4 eV, probably due to their small grain size.

2D Particle-in-Cell/Monte Carlo Collision Simulation of Zn-C Mosaic Target Erosion

In this work, a simulation analysis of a commercial magnetron sputtering source was performed using the finite element method Particle-in-Cell/Monte Carlo Collision (PIC/MCC) to optimize the configuration of the Zn-C mosaic target. The magnetic field distribution was solved in a two-dimensional cylindrical coordinate system, and particles such as electrons, atoms, and charged ions of argon, zinc, and carbon were tracked in a DC magnetron sputtering system. The sputtering yield profile and particle flux for the eroded target were studied considering the ion and electron density distributions. The maximum sputtering flux of zinc and carbon was 1.975´1021 m-2.s-1 and 3.7´1018 m-2.s-1 respectively. The erosion position of a target was predicted based on the maximum power density distribution at the surface of the target. The accuracy of the simulation was checked by comparing it with the measurement of the target eroded after several hours of sputtering. However, as for the Zn-C mosaic target, the racetrack was identical to the analysis predicted by the numerical simulation process. The results of this work can be used as a guide for designing mosaic targets and optimizing their use for fabricating nanohybrid thin film structures.

Structural, surface and optical investigations of Cu+ implanted NiO film prepared by reactive sputtering

Nickel oxide (NiO) films were deposited on silicon substrate using a DC magnetron sputtering system. The deposited films were annealed at 400 °C for 2 h and then irradiated by 500 keV copper ions (Cu+) in the dose range of 1 × 1011 to 1 × 1014 ions-cm−2 using Pelletron Accelerator. X-ray diffraction study revealed NiO and Ni phases in the films corresponding to (111) and (200) planes. The lattice parameter was increased with the increase of ion dose to 1 × 1012 ions-cm−2 and then decreased at the higher doses. Ion irradiation at 1 × 1011 ions-cm−2 improved the crystallinity of the film while at the higher doses, the crystallinity was decreased. The surface morphology of the films showed a decrease in the compactness of the granular structure with increasing the ion dose. Fourier Transform Infrared spectroscopy showed Cu–O and Ni–O stretching vibration peaks in the irradiated films. X-ray photoelectron spectroscopy (XPS) results revealed a decrease in NiO and increase in the Ni+3Ni+2 ratio with an increase of the ion dose to 1 × 1012 ions-cm−2, demonstrating an increase in the Ni vacancies in the film at lower doses. The depth-resolved XPS analysis displayed a change in the Ni and O atomic percentages in the film with the increase of the etching time from 50 to 250 s and validated the existence of metallic Ni in the NiO film. The photoluminescence (PL) spectra analysis showed a decreasing trend in the band gap of the NiO film irradiated up to 1 × 1012 ions-cm−2, then an increasing trend at the higher doses.

Preparation of Cotton-Zinc Composites by Magnetron Sputtering Metallization and Evaluation of their Antimicrobial Properties and Cytotoxicity.

The aim of this investigation was to evaluate the biological properties of cotton–zinc composites. A coating of zinc (Zn) on a cotton fabric was successfully obtained by a DC magnetron sputtering system using a metallic Zn target (99.9%). The new composite was characterized using scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), UV/Vis transmittance, and atomic absorption spectrometry with flame excitation (FAAS). The composite was tested for microbial activity against colonies of Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria and antifungal activity against Aspergillus niger and Chaetomium globosum fungal mold species as model microorganisms. Cytotoxicity screening of the tested modified material was carried out on BALB/3T3 clone mouse fibroblasts. The SEM/EDS and FAAS tests showed good uniformity of zinc content on a large surface of the composite. The conducted research showed the possibility of using the magnetron sputtering technique as a zero-waste method for producing antimicrobial textile composites.

Electrochemical Properties of Multilayered Sn/TiNi Shape-Memory-Alloy Thin-Film Electrodes for High-Performance Anodes in Li-Ion Batteries.

Sn is a promising candidate anode material with a high theoretical capacity (994 mAh/g). However, the drastic structural changes of Sn particles caused by their pulverization and aggregation during charge–discharge cycling reduce their capacity over time. To overcome this, a TiNi shape memory alloy (SMA) was introduced as a buffer matrix. Sn/TiNi SMA multilayer thin films were deposited on Cu foil using a DC magnetron sputtering system. When the TiNi alloy was employed at the bottom of a Sn thin film, it did not adequately buffer the volume changes and internal stress of Sn, and stress absorption was not evident. However, an electrode with an additional top layer of room-temperature-deposition TiNi (TiNi(RT)) lost capacity much more slowly than the Sn or Sn/TiNi electrodes, retaining 50% capacity up to 40 cycles. Moreover, the charge-transfer resistance decreased from 318.1 Ω after one cycle to 246.1 Ω after twenty. The improved cycle performance indicates that the TiNi(RT) and TiNi-alloy thin films overall held the Sn thin film. The structure was changed so that Li and Sn reacted well; the stress-absorption effect was observed in the TiNi SMA thin films.

Pico-molar level detection of copper ion with extraordinarily high response by Ti-doped copper nitride fabricated via high power impulse magnetron sputtering

Various specific methods have been exercised in recent years to detect heavy metal ions in drinking water or body fluids for environmental as well as health safety. Likewise, development of a simple, fast, and robust method for copper ion (Cu2+) sensing is of paramount importance. Here, we demonstrate an effective Cu2+ sensor by exploiting the change in electrical conductivity of Ti-doped copper nitride (Cu3N) in presence of Cu2+ in solution. The Cu2+ sensor was fabricated with a Ti-doped Cu3N film deposited on indium-tin-oxide (ITO) coated quartz glass substrate by co-deposition method using high-power impulse magnetron sputtering (HiPIMS) and DC magnetron sputtering system simultaneously. DC sputtering power of Ti source was tuned from 0 W to 200 W with 50 W steps to achieve the Cu3N film with doping concentrations of 0, 0.19, 0.33, 0.87, and 1.6 at% respectively. Application of a diluted Cu2+ solution on the Ti-doped Cu3N film increases its electrical conductivity dramatically as manifested in the increase in current measured between two consecutive ITO electrodes beneath the thin film. The extraordinarily high copper sensitivity of the Ti-doped Cu3N film (1.6 at%) originated from the nitrogen-rich surfaces leads to detection of Cu2+ in water at as low as 8 pM concentration. The sensor exhibits not only high response but also a large linear dynamic range of 8 pM to 80 nM well below the maximum contaminant level goal for copper ion in drinking water. The high selectivity and reasonable cross-sensitivity of the sensor show potential commercialization in near future.