Characterization Of Cu2ZnSnS4 Thin Films Research Articles

Characterization of Cu2ZnSnS4 thin films prepared with and without thin Al2O3 barrier layer

We investigated the effect of thin Al2O3 barrier layer (∼20 nm) deposited by radio frequency magnetron sputtering technique on the structural, morphological, optical, and electrical properties of Cu2ZnSnS4 (CZTS) films. Major differences in the crystalline qualities of the films were not observed with the addition of the Al2O3 layer except for a small decrease in crystallite size. Raman spectra of the film with the Al2O3 layer exhibited the peaks belonging to ZnS and Cu2-xS secondary phases. X-ray photoelectron spectroscopy analysis showed that SO42- and CuSO4 compounds were formed on the surfaces of the films. The formation of the CuSO4 phase was associated with the bonding between CuO and S in an oxidized CZTS surface. The presence of the ZnS, Cu2-xS secondary phases, and CuSO4 on the surfaces of the films were also confirmed by scanning electron microscopy images. The film with the Al2O3 layer differed from the other films with its surface that have randomly distributed porous-structured agglomerations and a decrease in the ZnS secondary phases on its surface. All films exhibited different Na distributions in secondary ion mass spectroscopy depth profiles. The Al2O3 layer caused a slower gradient in Na diffusion with decreasing the accumulation of Na element at a distinct region. The activation energy for the thermally activated band conduction was calculated as 0.030 eV and attributed to the thermal release of the holes from the vacancy of copper (VCu) defect states. The results of temperature-dependent conductivity measurements indicated that there were different conduction mechanisms in the films.

On the Deposition and Characterization of Cu2znsns4 Thin Films and Fabrication of Cadmium Free Heterojunction Solar Cells

On the Deposition and Characterization of Cu2znsns4 Thin Films and Fabrication of Cadmium Free Heterojunction Solar Cells

Computational and experimental characterizations of annealed Cu2ZnSnS4 thin films

We report on the synthesis and characterization of Cu2ZnSnS4 (CZTS) thin films prepared at different annealing temperatures using the sol-gel method and deposited on glass substrates using the immersing method. The XRD analysis demonstrates that the films annealed at 450 °C exhibit the most stable tetrahedral kesterite structure. Computationally, the Vienna ab initio simulation package (VASP) has been implemented to calculate critical structural properties of as-prepared CZTS) thin films and compared with those extracted from the XRD patterns. An excellent agreement is obtained between the calculated and measured structural parameters. Optical measurement of key optical parameters of annealed CZTS thin films shows a drastic manipulation of all-optical properties compared to the as-prepared thin films. In particular, an optical band gap of 1.62 eV obtained for annealed CZTS thin films at 450 °C makes them eligible to be potential candidates for thin film-based high-efficiency solar cells. Calculations of elastic properties of annealed thin films reveal that crystallite size increases and microstrain decrease compared with those of as-prepared thin films. The sheet resistance of annealed CZTS thin films exhibits a significant decline as the annealing temperature is increased. The electrical properties of annealed CZTS thin films could match some conductors. Remarkably, at 450 °C annealing temperature, the sheet resistance decreases to 74 Ω.cm−1 indicating the possibility of using the annealed CZTS thin films for efficient and low cost solar cell applications.

Synthesis and Characterization of Cu2ZnSnS4 Thin Films Obtained by Combined Magnetron Sputtering and Pulsed Laser Deposition.

Cu2ZnSnS4 (CZTS) is a complex quaternary material, and obtaining a single-phase CZTS with no secondary phases is known to be challenging and dependent on the production technique. This work involves the synthesis and characterization of CZTS absorber layers for solar cells. Thin films were deposited on Si and glass substrates by a combined magnetron sputtering (MS) and pulsed laser deposition (PLD) hybrid system, followed by annealing without and with sulfur powder at 500 °C under argon (Ar) flow. Three different Cu2S, SnS2, and ZnS targets were used each time, employing a different target for PLD and the two others for MS. The effect of the different target arrangements and the role of annealing and/or sulfurization treatment were investigated. The characterization of the absorber films was performed by grazing incidence X-ray diffraction (GIXRD), X-ray reflectometry (XRR), Raman spectroscopy, scanning electron microscopy, and regular transmission spectroscopy. The film with ZnS deposited by PLD and SnS2 and Cu2S by MS was found to be the best for obtaining a single CZTS phase, with uniform surface morphology, a nearly stoichiometric composition, and an optimal band gap of 1.40 eV. These results show that a new method that combines the advantages of both MS and PLD techniques was successfully used to obtain single-phase Cu2ZnSnS4 films for solar cell applications.

Preparation and characterization of Cu2ZnSnS4 thin films with various compositions deposited by a dual thermal evaporation technique

Cu2ZnSnS4 (CZTS) thin films were deposited successfully with four different compositions, namely, Cu-rich, Sn-rich, Zn-rich and near-stoichiometric CZTS, by a dual thermal evaporation technique to investigate the effect of stoichiometry on the physical properties of the deposited films. The thin films were characterized by energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction, Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and UV–VIS–NIR spectroscopy in the as-deposited state and after annealing in nitrogen at 350 °C for 30 min. It was found that the stoichiometry of the film played a critical role in the physical properties and stability after annealing. Increasing the amount of each element compared to that of the others impacted the colour, preferred orientation, grain size, microstrain, dislocation density, surface morphology, transmittance, reflectance, absorbance and band gap of the thin films. A (112) preferred orientation was obtained, and this orientation became more pronounced after the annealing of all films. The stoichiometry of the films changed after annealing due to re-evaporation of the sulfur, and the Cu-rich film was the most stable of the films studied herein. The estimated band gap (Eg) for the as-deposited films varied between 1.53 eV and 2.3 eV and were reduced to 1.1 eV for the Cu-rich film after annealing.

Characterization of Cu2ZnSnS4 thin films deposited by one-step thermal evaporation for a third generation solar cell

In this study, one-step thermal evaporation was employed for the fabrication of phase-pure CZTS thin films on glass substrates from single crystalline Cu-poor ingot grown by Bridgman technique. Structural analyses revealed the formation of a mono-phase CZTS kesterite structure for the thin films annealed at 450 °C under N2 atmosphere. The AFM measurements demonstrated significant morphological changes in films with increasing the annealing temperature from 200 °C to 450 °C, supporting the results obtained via XRD and Raman studies. From the optical measurements, the band gap was estimated to be 1.47 eV for the CZTS film annealed at 450 °C, which is close to the optimum value required for photovoltaic applications. As a device application of the optimized CZTS thin films, an attempt was made to construct a TiO2 NRs based and CdS-free FTO/TiO2 NRs/CZTS/Ag superstrate CZTS solar cells. TiO2 NRs were grown by hydrothermal technique, which offers a simple and a cost-effective route for large-scale production of one-dimensional nanostructures. The solar cell exhibited an open-circuit voltage of 0.35 V, a short-circuit current density of 7.28 mA/cm2, a fill factor of 23.9% and a power conversion efficiency of 0.61%, the highest efficiency recorded so far for a single-dimensional TiO2 nanostructures based superstrate CZTS solar cell.

The role of copper during the growth of stoichiometric Cu2ZnSnS4 by successive ionic layer adsorption and reaction method

The synthesis and characterization of Cu2ZnSnS4 (CZTS) thin films prepared on glass/CdS substrates by the successive ionic layer adsorption and reaction (SILAR) method are presented. The effect of copper concentration and atmosphere annealing on the properties of CZTS thin films were studied by means X-ray diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy (SEM), X-ray photoelectron spectroscopy (XPS), optical spectroscopy and current-voltage curves. The XPS depth profiling data revealed that a minima copper concentration in cationic solution is required to start the adsorption of zinc and tin ions at the CdS surface. The use of 0.001–0.002 M copper concentration allows the adsorption of zinc and tin ions in a suitable quantity inducing the formation of stoichiometric and polycrystalline CZTS thin films. Furthermore, it was found that above of this copper concentration, the segregation of Cu2S phase occurs, even when it is ten times smaller than Zn and Sn concentrations. Otherwise, the sulfurization process doesn't imply a significant change on the structural and chemical properties, as if it does in the optical and electrical properties. This suggests that the excess of Na2S used in the anionic solution is enough to compensate the loss of sulfur during the thermal annealing. The optical band gap energy and the electrical conductivity of these films were evaluated in the range of 1.41–1.53 eV and 10−1 Ω cm−1, respectively. All results suggested that this material is suitable for being applied as an absorber layer in photovoltaic solar cells.

Preparation and characterization of Cu2ZnSnS4 thin films by two-stage process

ABSTRACTCu2ZnSnS4 (CZTS) a quaternary semiconductor is potential candidate for absorber layer in thin-film heterojunction solar cell. Achieving CZTS thin films is really a challenging task using chemical methods. In this work, an attempt is made by mixing binary and ternary compound semiconducting films for the growth of CZTS films. Initially, ZnS thin films have been deposited by spray pyrolysis technique onto soda–lime glass substrates held at a substrate temperature of 698 K. Later, copper tin sulfide (Cu2SnS3 [CTS]), a ternary compound semiconducting film, has been deposited using spray pyrolysis technique onto ZnS-coated substrates held at a substrate temperature 598 K. For achieving CZTS films, ZnS/CTS films were annealed in sulfur ambiance at different annealing temperatures in a two-zone tubular quartz furnace. The structural, optical, electrical, and surface morphological studies are carried out for these thin films.

Effect of mixing complexing agents on the properties of electrodeposited CZTS thin films

This work involves the synthesis and characterization of Cu2ZnSnS4 (CZTS) layers. The films were prepared on ITO/glass substrate by ecofriendly and simple single-step electrodeposition method followed by sulfurization and annealing at 500 °C under Argon flow. By using two different complexing agents, the electrodeposition process can give better results. Therefore, the effect of combining the trisodium citrate - TC to multiple complexing agents (cetyl trimethyl ammonium bromide - CTAB, ethylene diamine tetra acetic acid - EDTA, Boric Acid - BA, Glutamic Acid - GA and Tartaric Acid - TA) is investigated. The characterization of the absorber films was done by X-ray diffraction (XRD) analysis, Raman spectroscopy, Scanning Electron Microscopy and Diffuse Reflectivity. The combination of TC and CTAB is suggested to be the best pair of complexing agents within the combinations used in this work.

Fabrication and characterization of Cu2ZnSnS4 thin films by sputtering a single target at different temperature

Cu2ZnSnS4(CZTS) thin films were directly deposited by sputtering with a single target at different temperatures, compared with the sulfurization process after sputtering the metal precursor, which is not only simplified the preparation process also the obtained CZTS thin film had good crystallinity with large grain size and dense morphology. The solar cell fabricated with the CZTS thin film sputtered at an optimized temperature of 500°C shows a conversion efficiency of 1.87% with Voc = 580mV, Jsc = 8.47mA/cm2, and FF = 37.8%, its band gap energy is found to be 1.52eV. These results show that the process without sulfurization is suitable for the growth of kesterite CZTS solar cell absorbers.

The synthesis and characterization of Cu2ZnSnS4 thin films from melt reactions using xanthate precursors

Kesterite, Cu2ZnSnS4 (CZTS), is a promising absorber layer for use in photovoltaic cells. We report the use of copper, zinc and tin xanthates in melt reactions to produce Cu2ZnSnS4 (CZTS) thin films. The phase of the as-produced CZTS is dependent on decomposition temperature. X-ray diffraction patterns and Raman spectra show that films annealed between 375 and 475 °C are tetragonal, while at temperatures <375 °C hexagonal material was obtained. The electrical parameters of the CZTS films have also been determined. The conduction of all films was p-type, while the other parameters differ for the hexagonal and tetragonal materials: resistivity (27.1 vs 1.23 Ω cm), carrier concentration (2.65 × 10+15 vs 4.55 × 10+17 cm−3) and mobility (87.1 vs 11.1 cm2 V−1 s−1). The Hall coefficients were 2.36 × 103 versus 13.7 cm3 C−1.

Deposition and characterization of Cu2ZnSnS4 thin films for photovoltaic applications

Cu2ZnSnS4 thin films were successfully deposited on glass substrates by a chemical bath deposition method for as-deposited and annealed films with different temperatures in sulphur atmosphere at 250 and 350 °C. The changes in structural and the optical phenomenon of as -deposited and annealed films have been studied. The powder X-ray diffraction (XRD) spectra show the tetragonal crystal structure of Cu2ZnSnS4(CZTS) thin films. The average crystallite size varies from 19.437 to 17.937 and 10.41 nm respectively, when the film was as-deposited and annealed at 250 and 350 °C. The surface morphologies of the as-grown surface show some voids with agglomerated particles. After sulphurization at 250 and 350 °C, the morphologies of the samples become dense. The band gap is estimated to be about 1.11 eV for the as-deposited film and 1.42 and 1.5 eV for the annealed films.

Fabrication and characterization of Cu2ZnSnS4 thin films for photovoltaic application by low-cost single target sputtering process

Highly crystallized single-phase Cu2ZnSnS4 thin films were fabricated using a simple single-target sputtering technique followed by low-cost sulfurization treatment with sulfur powder. The effects of sulfurization temperature (ranging from 400 to 550 °C) on the structure, morphology, composition, optical and electrical properties of the synthesized CZTS thin film were investigated systematically. The increased sulfurization temperature was found to affect the elemental composition slightly but significantly improve crystallinity, carrier mobility and optical band gap of CZTS films. In particular, the CZTS film sulfurized at 500 °C had excellent optical and electrical properties (an optical band gap of 1.53 eV, a hole concentration of 3.2 × 1015 cm−3, and a carrier mobility of 57.6 cm2(V.s)−1). Furthermore, CZTS-based solar cells were successfully fabricated. Current-voltage (J-V) characteristics indicated that the current density had a tendency of increase with the increase of sulfurization temperature, which was attributed to the relatively large grains and high mobility achieved at a high sulfurization temperature. Importantly, the solar cell based on the CZTS thin film sulfurized at 500 °C had the best performance with a photovoltaic conversion efficiency of 4.4%, open-circuit voltage of 650 mV, short-circuit current density of 19.2 mA/cm2, and fill factor of 37%.

XPS analysis and structural and morphological characterization of Cu2ZnSnS4 thin films grown by sequential evaporation

Abstract This work describes a procedure to grow single phase Cu 2 ZnSnS 4 (CZTS) thin films with tetragonal-kesterite type structure, through sequential evaporation of the elemental metallic precursors under sulphur vapor supplied from an effusion cell. X-ray diffraction analysis (XRD) is mostly used for phase identification but cannot clearly distinguish the formation of secondary phases such as Cu 2 SnS 3 (CTS) because both compounds have the same diffraction pattern; therefore the use of a complementary technique is needed. Raman scattering analysis was used to distinguish these phases. The influence of the preparation conditions on the morphology and phases present in CZTS thin films were investigated through measurements of scanning electron microscopy (SEM) and XRD, respectively. From transmittance measurements, the energy band gap of the CZTS films was estimated to be around 1.45 eV. The limitation of XRD to identify some of the remaining phases after the growth process are investigated and the results of Raman analysis on the phases formed in samples grown by this method are presented. Further, the influence of the preparation conditions on the homogeneity of the chemical composition in the volume was studied by X-ray photoelectron spectroscopy (XPS) analysis.

Characterization of Cu2ZnSnS4 Thin Films Prepared by Solution-based Deposition Techniques

Abstract Cu2ZnSnS4 (CZTS) compound semiconductor has attracted considerable interest for use in low-cost thin-film PVs because of its earth-abundant constituents, optimal band gap, and high absorption coefficient. In this paper, CZTS thin films have been successfully prepared on soda-lime glass substrates by solution-based deposition techniques. The CZTS nanocrystals were synthesized by hot-injection method from copper (II) acetylacetone, zinc (II) acetate, tin (II) chloride and sulfide powder in an argon protection atmosphere. The as-synthesized nanocrystals were characterized by transmission electron microscopy (TEM). The structure, morphology, composition, and optical properties of the CZTS films were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry, and UV-vis spectrometry. The XRD analysis demonstrated that CZTS thin films possessed a single- phase kesterite structure and no secondary phases were observed in the XRD diffraction pattern. The SEM micrographs showed the CZTS films were uniform, dense and had almost no voids. The chemical composition of CZTS films was nearly stoichiometric. The band gap was about 1.57 eV and the annealed CZTS thin films are very suitable for the absorber of solar cells.

Preparation and Characterization of Cu2ZnSnS4 Thin Films and Solar Cells Fabricated from Quaternary Cu-Zn-Sn-S Target

CZTS thin films were fabricated through sputtering from a quaternary Cu-Zn-Sn-S target, followed by a sulfurization process. CZTS thin-film solar cells were also fabricated and a highest efficiency of 4.04&#x25; was achieved. It has been found that obvious Zn loss occurs during the sputtering and poorly crystallized CZTS are formed in the sputtered films. The Zn loss leads to the appearance of SnS. A sulfurization process can obviously improve the crystallinity of CZTS and films with grain size of several hundred nanometers can be obtained after sulfurization. The optical band gap of the films is estimated to be 1.57&#x2009;eV. The electrical properties of the 4.04&#x25; efficient solar cell were investigated and it has been found that cell has obvious deficiency in minority carrier lifetime. This deficiency should be responsible for the low <svg style="vertical-align:-3.39064pt;width:18.012501px;" id="M1" height="15.4" version="1.1" viewBox="0 0 18.012501 15.4" width="18.012501" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,11.112)"><path id="x1D43D" d="M434 650l-5 -28q-60 -8 -75 -20.5t-25 -69.5l-71 -395q-20 -107 -57.5 -168t-106.5 -94q-40 -18 -61 -20l-10 32q77 23 113 108q21 50 41 160l68 377q10 57 -1.5 69.5t-76.5 20.5l6 28h261z" /></g> <g transform="matrix(.012,-0,0,-.012,7.825,15.187)"><path id="x73" d="M319 325l-25 -7q-33 99 -103 99q-29 0 -47 -19.5t-18 -49.5t22 -49.5t62 -36.5q63 -26 95 -57t32 -79q0 -64 -50 -101t-115 -37q-35 0 -67.5 10.5t-46.5 23.5q-5 11 -11 51t-6 67l27 5q14 -53 46.5 -88.5t75.5 -35.5q29 0 50 19.5t21 50.5t-19.5 51.5t-59.5 39.5&#xA;q-28 12 -46 22.5t-38.5 27t-30.5 38.5t-10 49q0 54 42.5 92t109.5 38q48 0 88 -18q6 -15 13 -50.5t9 -55.5z" /></g><g transform="matrix(.012,-0,0,-.012,12.287,15.187)"><path id="x63" d="M390 111l17 -21q-34 -45 -80 -73.5t-89 -28.5q-91 0 -146 62t-55 147q0 118 101 195q74 57 149 57h1q59 0 90 -27q16 -14 16 -30q0 -15 -12 -29t-21 -14q-8 0 -19 11q-44 41 -101 41q-52 0 -87.5 -42.5t-35.5 -117.5q0 -49 15 -87t39 -58t49 -30t48 -10q33 0 60.5 12&#xA;t60.5 43z" /></g> </svg> and low <svg style="vertical-align:-3.39064pt;width:24.575001px;" id="M2" height="15.4" version="1.1" viewBox="0 0 24.575001 15.4" width="24.575001" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,11.112)"><path id="x1D449" d="M730 650l-8 -28q-52 -4 -72 -18t-64 -77q-79 -113 -321 -539h-33l-119 541q-13 59 -29.5 73t-66.5 20l7 28h245l-8 -28l-28 -5q-33 -6 -40.5 -15.5t-0.5 -38.5l102 -450h2q191 320 246 430q21 42 15.5 56t-43.5 19l-31 4l7 28h240z" /></g> <g transform="matrix(.012,-0,0,-.012,12.675,15.187)"><path id="x6F" d="M257 449q92 0 154 -65t62 -158q0 -112 -67 -175t-150 -63q-98 0 -158.5 66.5t-60.5 154.5q0 59 21 106.5t54.5 75.5t71 43t73.5 15zM244 416q-48 0 -81 -47t-33 -128q0 -96 38 -158t99 -62q51 0 82 43.5t31 139.5q0 91 -36 151.5t-100 60.5z" /></g><g transform="matrix(.012,-0,0,-.012,18.85,15.187)"><use xlink:href="#x63"/></g> </svg> of our cell.

Synthesis and characterization of Cu2ZnSnS4 thin films by SILAR method

Semiconducting Cu2ZnSnS4 (CZTS) material has been receiving a great technological interest in the photovoltaic industry because of its low-cost non-toxic constituents, ideal direct band gap as a absorber layer and high absorption coefficient. CZTS thin films have been successfully deposited onto the fluorine-doped tin oxide/glass (glass/FTO) substrates coated glass substrates using successive ionic layer adsorption and reaction (SILAR) method and investigated for photoelectrochemical conversion (PEC) of light into electricity. The best solar cell sample showed an open-circuit voltage of 390mV, a short-circuit current density of 636.9μA/cm2, a fill factor of 0.62 and an efficiency of 0.396% under irradiation of 30mW/cm2. Preliminary results obtained for solar cells fabricated with this material are promising.

In situ growth and characterization of Cu2ZnSnS4 thin films by reactive magnetron co-sputtering for solar cells

Cu2ZnSnS4 (CZTS) thin films have been first in situ grown by reactive magnetron co-sputtering and its characterizations has been carried out by energy dispersive spectroscopy(EDS), X-ray diffraction(XRD), scan electron microscope(SEM), optical transmittance and electronic measurement. It was observed that the grown film shows homogeneous, compact surface morphology, and consists of large columnar grains throughout the thickness. The atom ratio Cu/(Zn+Sn) is about 1, while Zn/Sn is larger than 1 and decreases with the increase of substrate temperature. XRD analysis indicates that the grown film exhibits strong preferential orientation along (112) plane and the structural properties depend on growth temperature and Cu/(Zn+Sn) ratio. The in situ grown CZTS film has an optical absorption coefficient higher than 104 cm-1, and the optical band gap becomes narrow with the increase of substrate temperature and achieves (1.51±0.01)eV at 500℃. The conduction type of the CZTS films is p-type and the value of carrier concentration is comparable with values of device quality CIGS.

Characterization of Cu2ZnSnS4 Thin Films Prepared by Photo-Chemical Deposition

Cu2ZnSnS4 thin films were prepared by photo-chemical deposition (PCD) from aqueous solution containing CuSO4, ZnSO4, SnSO4 and Na2S2O3. The compositional ratio of the films was dependent little on pH of aqueous solution and the surface of the samples became smooth by use of aqueous filter. A sample annealed at 400°C was a p-type semiconductor and showed photoconductivity. This is the first observation of photo-conductivity from semiconductor films deposited by PCD, to the best of our knowledge.

Characterization of Cu2ZnSnS4 Thin Films Prepared by Vapor Phase Sulfurization

Cu2ZnSnS4 (CZTS) thin films could be successfully formed by vapor phase sulfurization of electron-beam-evaporated precursors on a soda-lime glass substrate. This film is an interesting material for absorber layer in a solar cell because all the constituents are readily available in the earth's crust. In this study, using a new type of precursors containing ZnS, we could achieve the strong adhesion of CZTS films to a glass substrate. From the result of scanning electron microscope (SEM) observation, it was confirmed that the surface morphology of CZTS films is much improved by using this new type of precursor. The X-ray diffraction pattern revealed that CZTS thin films have kesterite structures. From the measurement of transmittance and reflectance, the optical band-gap energy was estimated as 1.40–1.45 eV, which is very close to the optimum value for a solar-cell absorber. The highest open-circuit voltage of our cells based on CZTS films is 735 mV, which is a higher value than that reported in numerous other studies on CZTS.