Hot Probe Method Research Articles

Enhancing Low-Temperature Sensor Applications: Synergistic Effects of Ni Doping and SnO2 Interlayer on Spin-Coated ZnO Thin Films on Glass Substrate

This study investigates the effects of Nickel doping and a SnO2 interlayer on the structural, morphological, optical, and electrical properties of ZnO thin films. Undoped and Ni-doped ZnO films were fabricated on glass substrates, with and without an SnO2 interlayer, using the sol-gel spin coating method. The samples—denoted as ZG (undoped ZnO), NZG (Ni-doped ZnO), ZSG (undoped ZnO with SnO2 interlayer), and NZSG (Ni-doped ZnO with SnO2 interlayer)—underwent comprehensive characterization via XRD, AFM, PL, UV-Vis spectroscopy, Hall effect measurements, Hot probe, and Two-point method. XRD analysis confirmed successful Ni incorporation and enhanced ZnO crystallinity, particularly in the presence of the SnO2 interlayer. AFM analysis revealed improved grain distribution and size due to the synergistic effects of Ni doping and the SnO2 interlayer. UV-Vis results indicated significant impacts on transparency and the Urbach energy, with Ni doping alone broadening the bandgap. PL measurements showed that the synergistic effects quenched UV luminescence associated with the glass substrate, enhancing visible luminescence. Chromaticity analysis suggested that ZSG and NZSG samples are suitable for warm blue region applications. Electrical measurements revealed n-type conductivity across all films except NZG, with Ni doping increasing resistivity. Additionally, the ZSG (PTC) sensor exhibited a slightly higher sensitivity (0.3852 Ω/°C) compared to the NZSG sensor (0.3782 Ω/°C), with a similar trend observed in NTC sensors. These findings suggest that Ni-doped ZnO films with SnO2 interlayers could potentially serve as thermistors and RTDs, offering promising applications in temperature sensing and optoelectronics.

Optical and electrical properties of Ni+2 doped nanocrystalline Bi2S3 thin films prepared by chemical bath deposition method

Nickel (Ni+2) doped nanocrystalline Bi2S3 thin films are deposited on the glass substrate from the solutions containing Bismuth Nitrate, Ethylenediamine Tetraacetic acid (EDTA) and Thioacetamide at a bath deposition temperature of 318K. The optical, surface morphological and electrical properties of Ni-doped Bi2S3 thin films prepared at three different doping concentration are investigate by using ultraviolet–visible transmission spectra (UV–Vis), Scanning electron microscopy (SEM), Energy Dispersive X-ray (EDAX) and thermo-e.m.f. techniques. The optical band gap energies are found in between 2.32-2.43 eV. The SEM images show that the prepared films are continuous, dense and distributed over the entire area with good uniformity. The electrical conductivity of the films are in the order of 10-2 Ω-1 m-1 . The films are n-type as determined from the Hot Probe method. Photoconductivity studies reveal that photocurrent increases with the increase in Ni doping concentrations. Due to the absorption of photons, free electron-hole pairs (EHP) are produce.

Synthesis, structural, optical and electrical properties of CuxSbySz powders

The family of chalcogenides appears as promising candidates to act as absorbers in alternative solar cells in order to reduce the dependence on fossil fuels. The five absorber materials, CuSbS2, Cu3SbS3, Cu3SbS4, Cu12Sb4S13 and Cu14Sb4S13, were synthesized by the direct fusion of the elements inside evacuated quartz tubes. The resulting ingots were characterized electrically by the hot probe method and by direct resistance measurement. These ingots were then ground in order to obtain very fine powders. Also their pellets were characterized by X-Ray Diffraction, Raman spectroscopy, optical and electrical analysis. The X-Ray diffraction and Raman spectroscopy results confirmed the material's purity. Their band gap energies were determined by the Kubelka-Munk model, and found to be ranging between 1.24 and 1.47 eV. The five materials have P-type conductivities.

Effects of Solution pH on Chemical Bath Deposited Iron-Sulfide-Oxide with Tartaric Acid Presence

A chemical bath deposition (CBD) contained sodium thiosulfate (Na2S2O3), iron (II) sulfate heptahydrate (FeSO4.7H2O), and L(+)-tartaric acid (C4H6O6) as the complexing agent has been used to deposit the iron-sulfide-oxide (FeSxOy) films. The effects of different solution pH (5.0-9.0) on film properties were investigated. The thicknesses of the film analysed from the cross-sectional images of Scanning Electron Microscopy (SEM) showed the thickness of the film is increasing with increasing pH. The X-Ray Diffraction (XRD) pattern and the hot probe method revealed that all the deposited films are crystalline, and possess n-type semiconductor behaviour due to high oxygen content (around 72-82%). Larger crystallite sizes with extra peaks of goethite and hematite were present for the films with pH > 7.0, while, better film uniformity and grains distribution, as well as clear absorption edge in transmittance measurement, were obtained for the film with pH 5.0.

N-type CdTe:In for photovoltaics: in situ doping, type verification and compensation effects

We explored the in-situ doping of cadmium telluride thin films with indium to produce n-type absorbers as an alternative to the near-universal choice of p-type for photovoltaic devices. The films were grown by close space sublimation from melt-synthesised feedstock. Transfer of the indium during film growth was limited to 0.0014%–0.014%—unless reducing conditions were used which yielded 14%–28% efficient transport. While chunks of bulk feedstock were verified as n-type by the hot probe method, carrier type of thin film material was only able to be verified by using hard x-ray photoelectron spectroscopy to determine the Fermi level position within the band gap. The assignment of n-type conductivity was consistent with the rectification behaviour of a p-InP/CdTe:In junction. However, chloride treatment had the effect of compensating n-CdTe:In to near-intrinsic levels. Without chloride, the highest dopant activation was 20% of the chemical concentration of indium, this being for a film having a carrier concentration of n = 2 × 1015 cm−3. However, the activation was often much lower, and compensation due to over-doping with indium and native defects (stoichiometry) are discussed. Results from preliminary bifacial devices comprising Au/P3HT/ZnTe/CdTe:In/CdS/FTO/glass are presented.

Synthesis and characterization of peculiar (Sb0.2Sn0.8)0.5(Se0.9S0.1)0.5 crystal and its application as visible light photo-detector

To investigate the influence of Sb and S inclusion on SnSe characteristics, alloy engineering is carried out. The (Sb0.2Sn0.8)0.5(Se0.9S0.1)0.5 quaternary crystal was well synthesized via direct vapour transport (DVT) technique. The surface morphology, chemical composition, structural, optical, electrical, and photoconductive characteristics of the grown crystal were estimated using acceptable methodologies. The FE-SEM image revealed that the (Sb0.2Sn0.8)0.5(Se0.9S0.1)0.5 crystal has a flat surface, and the chemical composition was established using EDAX. X-ray diffraction (XRD) spectra further validated the orthorhombic structure of the crystal. Raman spectroscopy was employed to find different vibrational modes. The crystal exhibits a direct bandgap of 1.42 eV. The four-probe method and hot point probe method examination revealed the crystal to be an n-type semiconducting material. Additionally, an analysis of the pulsed photo response was carried out on the grown crystal, which was exposed to different wavelengths and white light at varying intensities, while subjected to a biasing voltage of 1 V, with an on/off period of 10 s. The results indicated that the device demonstrated rapid response to incident light, along with the presence of a trapping state, and favourable photodetection parameters, making it a viable material for a visible light photodetector.

Annealing time dependence on the structural, optical, optoelectrical, and electrical properties of copper antimony sulfide thin film synthesized using the dip coating method

Copper antimony sulfide (CAS) thin films were synthesized by the dip coating method and annealed at 473 K for different annealing times (1, 2, 3, 4, and 5 h). The nature of the structural and phase compositions of the CAS thin films were investigated using an x-ray diffractometer. For the annealing times of 1–4 h, the structural parameters of the thin films were evaluated, such as d-spacing (dhkl), crystallite size (D), microstrain (ε), and dislocation density (δ). The transmittance and reflectance spectra were analyzed to evaluate the linear optical, optoelectrical, dispersion, and nonlinear optical properties. Their values were increased as the CAS thin films were annealed for 1–3 h, and then decreased for 4–5 h. The resistance with temperature for the CAS thin films was measured by a two-probe method and obtained results in the range of ∼108–1010 Ω. The results show that the CAS thin films exhibit static dissipative behavior for the annealing times of 1–2 h, but reach an antistatic material state for the annealing time of 3 h. In addition, the hot-probe method was used to investigate the majority of carriers in the thin films. A negative voltage was shown and indicated the p-type properties for the synthesized CAS thin films.

Optical characteristics of chemically deposited MnSb2S4 thin films

In this research work, manganese antimony sulfide (MnSb2S4) films have been prepared and deposited via the chemical bath deposition route at various thicknesses (189, 275, 329, and 412 nm). The X-ray diffraction results confirmed the polycrystalline character of these films, which exposed orthorhombic structures. The compositional element percentages of these layers were analyzed via energy-dispersive X-ray spectroscopy. The impact of thickness on the optical characteristics of films has also been studied. The optical investigations manifest that these MnSb2S4 films demonstrate a direct optical transition with variable energy gap values (1.77–1.53 eV). The refractive index, optical dielectric constant, absorption coefficient, extinction coefficient, optical conductivity, and others have been estimated and studied. Additionally, the dispersion refractive index, dispersion, and oscillator energies of these spray-deposited films were computed and discussed. In the same way, increasing the thickness of the film has been shown to improve the nonlinear optical parameters. The hot-probe method using a negative voltage was used to investigate the semiconductor behaviour of MnSb2S4 films. It was found that these films tend to behave as p-type semiconductors. This study showed that MnSb2S4 films were utilized as a new absorber layer in photovoltaics.

Nano-crystalline tin selenide thin films: synthesis and characterization

A simple, straightforward, and facile drop-casting technique was used to prepare thin films of tin selenide (SnSe) at 220 °C substrate temperature using triethanolamine as complexing agent. SnCl2 and Na2SeSO3 precursors were used as source materials for the thin film synthesis. The drop-casted film was annealed at 400 °C. Surface morphological, structural, electrical, and optical properties of the synthesized films were analyzed by scanning electron microscope (SEM), energy dispersive X-ray analysis (EDAX), X-ray powder diffraction (XRD), high-precision digital multimeter, and UV–visible spectroscopy, respectively. The XRD study of synthesized film showed the presence of nanocrystallinity with orthorhombic crystal structure of SnSe. SEM images indicated that small grains agglomerated to form a bunch of bigger size. SEM data showed good continuity of SnSe film. Hot probe method was used to confirm the carrier type of film. SnSe thin films were p-type having 1.4 eV bandgap, and their electrical conductivity was in the order of 10 S cm−1 which made them suitable to use it in the solar cell as an absorber layer.

Growth and characterization of stochiometric PbxZn1-xS (x = 0.5) thin films by spray pyrolysis for solar cell window applications

Mixed II-IV-VI compounds are important because of the possibility of band gap tuning. Attempts have been made to grow polycrystalline PbxZn1-xS (x = 0.5) thin films by the spray pyrolysis technique. Films have been grown on glass substrates at substrate temperature 400 °C. X-ray diffractometer studies reveals that the films are cubic in nature with a preferred orientation along (111) texture. By the EDAX analysis the Stoichiometry of the deposited films was confirmed. SEM photographs show that the films were smooth and homogeneous. The transmittance measurements in the UV– VIS wavelength range show the optical band gap of 2.11 eV. Hot probe method reveals that films exhibit n type conductivity. The measurement of resistance with temperature revealed the extrinsic activation energy of 0.28 eV.

CCF-LRU: hybrid storage cache replacement strategy based on counting cuckoo filter hot-probe method

CCF-LRU: hybrid storage cache replacement strategy based on counting cuckoo filter hot-probe method

Hot-Probe Method for Majority Charge Carrier Determination in Methylammonium Lead Halide Perovskites

Perovskites, due to their promising capabilities, are among the major candidates to substitute early-generation silicon solar cells. Despite their outstanding electrical and optical properties, actual comprehension of their behavior requires further studies and also investigation tools. It is shown that vacancy traps in organic-inorganic perovskites induce different polarities, where lead and methylamine vacancies posses p- and n-type polarity, respectively. Referred to as the self-doping property, different molar ratios of chemical precursors lead to controllable polarity and intrinsic doping. In other reports, thermal annihilation is also shown to convert p-type perovskite to n-type. According to the broad range of synthesized perovskites and their current application and promising future in optoelectronic devices, a simple, quick, and dependable method for trap concentration and major carrier-type determination is essential. Hot probe is a simple, affordable, and fast method for extracting polarity type in bulk and thin-film semiconductors. So far, this method and its variations have been applied for measuring conductivity, polarity, and impurity concentration in diverse ranges of semiconductors. In this method, free carriers are generated by raising the temperature of hot-probe contact and induced diffusion from this contact toward the other cold contact is studied. An equilibrium state is reached as a result of the formed built-in electric field between the cold and hot electrodes and also temperature elevation of this cold electrode, which act as diffusion dampers. Here, different types of organic-inorganic perovskites are synthesized and their electrical behavior is evaluated by the hot-probe method. Finally, it is concluded that the hot-probe approach is a dependable, fast, and accurate method to be applied in the field of perovskite material evaluations.

Synthesis, Growth and Characterization of Cu2CoSnS4 Thin Films via Thermal Evaporation Method

Quaternary sulfide Cu2CoSnS4 (CCTS) thin films were deposited by vacuum thermal evaporation on heated substrates. The substrates temperatures are ranged from room temperature to 200 °C. After what, the as-deposited films were sulfurized under vacuum at 450 °C to optimize the stoechiometric stannite CCTS phase. The crystalline structure of the sulfurized CCTS thin films was examined by X-ray diffraction technique and Raman spectroscopy. Surface morphological, elemental compositions and optical properties were explored by scanning electron microscopy, energy dispersive spectroscopy and spectrophotometer UV-VIS-NIR, respectively. X-ray diffraction and Raman analysis confirm that the sulfurization process leads to the formation of single CCTS phase. Optical results show high absorption coefficients of 105 cm-1 in the visible range with direct optical band-gap in the range 1.40-1.43 eV. In addition, the p-type conductivity of CCTS thin films was confirmed by hot probe method. The degradation of methylene blue in the presence of post-sulfurized samples was found in the range of 62-73%. Optical and Photocatalytic properties proves that post-sulfurized samples are suitable for application in photovoltaic and photocatalysis.

Cost-effective SnS heterojunction solar cells synthesized by spray pyrolysis

The present study reports, synthesis and fabrication of SnS/n-Si (100) heterojunction solar cell by a cost-effective spray pyrolysis technique. XRD peaks resemble orthorhombic SnS. XRD and SEM study reveals crystal/grain size as 15 and 26.4 nm, respectively. The SnS surface is closely packed, and composition of Sn and S element weight% found to be 96.58 and 3.42, respectively, and hot probe method confirms intrinsic p-type conductivity due to excesses Tin in films. Raman spectral analysis confirms the SnS phase along with Sn2S3 and SnS2. Isochronal and isothermal studies show that film sheet resistivity attains lowest value of 1.7248 × 10−2 Ωcm when annealed at 200 °C for 15 min. From M-S contact studies, estimated reverse saturation current density, ideality factor, knee voltage, barrier potential, and disorder energy are found to be 3.0563 × 10−10 A cm−2, 1.5225, 0.158 V, 0.7669 eV, and 0.0864 eV. Solar cell exhibits a typical rectifying diode behavior and its series resistance decreases from 41.44 to 16.66 kΩ as film thickness increases from 37 to 63 nm under illumination of 206 mW cm−2.

Structural, morphological and electrical properties of the Al/p-Cu2FeSnS4 thin film Schottky diode grown by two method

This work highlights some physical properties of Al/p-Cu2FeSnS4 Schottky diode fabricated by a two-stage method. Foremost, the Cu2FeSnS4 (CFTS) thin film was grown using thermal evaporation method onto heated Mo substrate temperature at 150 °C. After that, the as-deposited CFTS sample was annealed in a sulfur atmosphere at 400 °C for 30 min. Structural and morphological characterization were carried out by X-Ray diffraction, Raman scattering and scanning electron microscopy, whereas electrical study of Al/p-Cu2FeSnS4 junction was performed by using the current-voltage (I-V) measurement. Structural study revealed the presence of stannite CFTS phase and other peaks like Mo and MoS2. The hot probe method indicates that CFTS thin film exhibit p-conductivity type, also the film thickness was around 500 nm. The I-V characteristics showed that a Schottky contact was obtained between Aluminum and p-Cu2FeSnS4 absorber layer. The saturation current, the ideality factor and series resistance were determined from I-V experimental data. These parameters show important electrical properties such as a low series resistance and an ideality factor between 1 and 2.

One-pot green synthesis of copper sulfide (I) thin films with p-type conductivity

In this work we describe a novel and eco-friendly, low temperature synthesis of copper sulfide (I) Cu2S thin films. Chemical bath deposition was successfully applied for the Cu2S films deposition from acidic aqueous solutions of sodium thiosulfate Na2S2O3. The characterization of the prepared films was accomplished through elemental analysis, scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Raman and transmittance spectroscopy, and hot point probe method. The potential application in solar cells and photocatalysis was demonstrated by the measuring the optical properties and conductivity type of the Cu2S thin films.

Synthesis and Characterization of Next Generation Cu2ZnxFe1−xSnS4 (x = 0, 0.25, 0.5, 0.75 and 1) Compounds

In this paper, we investigate the effect of Zn/Fe ratio on the properties of Cu2ZnxFe1−xSnS4 (CZFTS) compounds. Multicomponent CZFTS powders were prepared by direct melting of the constituent elements taken in stoichiometric compositions. After that, CZFTS thin films were fabricated using a single source vacuum thermal evaporation method. After that, CZFTS thin films were annealed in sulfur atmosphere under nitrogen flow at 400°C for 30 min. Structural properties of CZFTS powders and thin films were studied by elemental composition measurement, x-ray diffraction (XRD) and Raman spectroscopy. Analysis of chemical compositions reveals that the synthesized CZFTS powders are close to the expected stoichiometry. XRD patterns and Raman spectra of CZFTS powders showed that only polycrystalline CZFTS phase is present and a possible transition phase from stannite to kesterite structure had occurred by reducing Fe content. Using XRD data, the crystal parameters of CZFTS powders were estimated. Structural properties of CZFTS thin films indicate an enhancement of crystallinity after annealing. Some microstructural parameters of the prepared films were evaluated. However, morphological analysis of CZFTS crystals showed compact surfaces. Also, micrographs of CZFTS thin films indicate an improvement of crystallinity films followed by the increases of average roughness values after a sulfurization process. Moreover, hot probe method indicates that CZFTS ingots and prepared films exhibit an obvious p-type semiconductor.

Physical and chemical study of the dependence of substrate temperature on properties of Cu3SbS3 thin films

This work highlights the effect of substrate temperature on the properties of Cu3SbS3 thin films grown on unheated and heated glass substrates, by vacuum thermal evaporation. The as-deposited film is elaborated at room temperature (25 °C). The heated substrates are processed at various temperatures, ranging from 70 °C to 180 °C. Cu3SbS3 powder was successfully synthesized by direct fusion method. The obtained films were assayed for their structural, morphological, optical and electrical properties using several techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive X-ray Spectrometry analysis (EDXS), UV‐VIS‐NIR spectrophotometer and hot probe method, respectively. First, the XRD analysis shows amelioration in the structural properties by increasing the substrate temperature. The microstructural parameters of all films were investigated such as crystallite size, strain and dislocation density. Second, the optical analysis shows that thin films have high absorption coefficients ranging between 105 and 106 cm−1. In addition, as per the models of Wemple–DiDomenico and Spitzer-Fan other optical and dielectric constants were estimated. Finally, the electrical study reveals that the p-type electrical conductivity is verified in all the samples.

FABRICATION AND CHARACTERIZATION OF TiO2 THIN FILM FOR DEVICE APPLICATIONS

Titanium oxide (TiO2) film was deposited by rectification factor (RF) magnetron sputtering technique on glass substrates and p-Si (111) wafers to fabricate n-TiO2/p-Si heterojunction devices for the investigation of material and device properties, respectively. The structural, surface morphology, optical and electrical properties of TiO2 film were characterized by means of scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), UV–visual (UV–Vis) spectral and dark current-voltage (I–V) measurement analyses. The deposited film layer was found to be homogeneous structure with crack-free surface. The bandgap value of TiO2 film was determined as 3.6[Formula: see text]eV and transmission was around 65–85% in the spectral range of 320–1100[Formula: see text]nm. The conductivity type of the deposited film was determined as n-type by hot probe method. These values make TiO2 film a suitable candidate as the n-type window layer in possible diode applications. TiO2 film was also deposited on p-Si (111) wafer to obtain Al/n-TiO2/p-Si/Al heterojunction device structure. The dark I–V characteristic was studied to determine the possible conduction mechanisms and diode parameters.

Microcontroller-based test system for determining the P-N type and Seebeck coefficient of the thermoelectric semiconductors

In this study, a microcontroller-based test system is designed and realized to determine the Seebeck coefficient (α) and electrical conductivity type of thermoelectric (TE) semiconductors. The test system uses Hot-Probe method, which benefits from the Seebeck effect. It is an embedded system based on the principle of measuring the Seebeck voltage (thermo-emf) produced once a temperature difference (ΔT) between the surfaces of the TE semiconductors is created. Seebeck coefficient of TE semiconductors can be determined depending on the thermo-emf and temperature measurements in the system. TE semiconductor electrical conductivity type (P or N) can also be determined according to the sign of the measured thermo-emf. The system consists of two major components, the main unit and the multifunctional probe. Thanks to the developed multifunctional probe, it is possible to provide the necessary heat for the temperature difference as well as Seebeck voltage and temperature measurements. In the main unit of the system, an 8-bit Atmega328 microcontroller is used and its software is developed with mikroC Pro for AVR. For various temperature differences between the surfaces of 9 P-type and 9 N-type TE semiconductors of various shapes and sizes obtained by Zone Melting (ZM), Hot Pressing (HP) and Hot Extrusion (HE) methods, the changes in thermos-emfs of the materials are investigated. In addition, Seebeck coefficient, P-N electrical conductivity type, and figure-of-merit (ZT) parameters of semiconductors, which are important for TE module production, are found. According to the experimental results, with the developed test system, the thermo-emf measurements can be made in an accuracy of ±0.1 mV within 0–100 mV range, and the temperature measurements can have accuracy of ±1 °C within 0–75 °C range. As a result, it is seen that the developed test system is a research device which can determine the Seebeck coefficient and P-N electrical conductivity type practically, quickly and reliably irrespective of the shape and size of TE semiconductors.