Schottky Behavior Research Articles

Behaviour of Ti/Al/Ti/Au contacts to AlGaN/GaN heterostructures at low temperature

Abstract Ohmic contacts to wide bandgap nitrides have been realised, but little is known about their behaviour at low temperatures. To address this, an established Ti/Al/Ti/Au contact stack on AlGaN/GaN heterostructures has been characterised from 320 K to 80 K. Two structures were investigated, with very similar ambient 2DEG transport characteristics despite their difference in AlGaN barrier thickness and composition. This allowed for direct comparison of contact behaviour across different heterostructures. Upon annealing at <800 °C for samples with 29 nm AlGaN barriers, contacts which had Ohmic characteristics at room temperature exhibited a gradual onset of Schottky behaviour as the measurement temperature was lowered. When non-Ohmic behaviour was observed, a combination of direct tunnelling, Fowler-Nordheim tunnelling and a thermally assisted Fowler-Nordheim mechanism is suggested to describe the carrier transport. In this case, annealing at 800 °C for 30 s proved sufficient to ensure Ohmic behaviour when tested from 320 K to 80 K. For a heterostructure with 8 nm AlGaN, the required annealing temperature to maintain consistent Ohmic behaviour across the temperature range was reduced to 750 °C. From these observations, the determining factor for Ohmic behaviour is suggested to be the thickness of the AlGaN barrier – either as-grown, or the effective thickness following the formation of TiN protrusions into the AlGaN barrier during annealing. The understanding provided here allows tailoring of either the processing conditions or the heterostructure, and may aid with design of novel devices for low temperature operation.

Polypyrrole-bismuth tungstate/polypyrrole core-shell for optoelectronic devices exhibiting Schottky photodiode behavior

A polypyrrole-bismuth tungstate (Ppy-Bi2WO6) core-shell nanocomposite (n-type material) has been developed on a layered Ppy (p-type) base as an efficient light-capturing material exhibiting photodiode behavior. This device demonstrates promising sensitivity for light sensing and captures across a broad spectral range, from near IR to UV. The Bi2WO6/Ppy nanocomposite boasts an optimal bandgap of 2.0 eV, compared to 3.4 eV for Ppy and 2.5 eV for Bi2WO6. The crystalline size of the core-shell composite is approximately 21 nm, emphasizing its photon absorption capabilities. The composite particles, around 100 nm in length, feature a highly porous morphology that effectively traps incident photons. The performance of this optoelectronic device is evaluated using current density (J) measurements under light (Jph) and dark (Jo) conditions. In darkness, the n-p type semiconductor exhibits limited current with a Jo of −0.22 mA cm−2 at 2.0 V. When exposed to white light, the Ppy- Bi2WO6/Ppy device generates hot electrons, achieving a Jph value of 1.1 mA/cm−2 at 2.0 V. It shows a superior responsivity (R) of 6.6 mA/W at 340 nm, gradually decreasing to 6.3 mA/W at 440 nm and 4.2 mA/W at 540 nm, indicating high sensitivity across the UV-Vis spectrum. At 730 nm, the R-value is 2.6 mA/W, highlighting its sensitivity in the near IR region. Additionally, at 340 nm, the device achieves a detectivity (D) value of 0.15 × 10¹⁰ Jones, which decreases with longer wavelengths to 0.14 × 10¹⁰ Jones at 440 nm, 0.9 × 10⁹ Jones at 540 nm, and 0.63 × 10⁹ Jones at 730 nm. With its great stability, low cost, easy fabrication, and potential for mass production, this optoelectronic light sensor and photodiode device holds significant promise for industrial applications as a highly effective optoelectronic device.

Observation of doping-induced spin–orbit coupling in gold cluster assembly to carrier-tuneable semiconductors and Schottky behaviors

The doping influenced carrier dynamics to maneuvering n-type to p-type semiconducting gold cluster assembly have been assessed. The resonance photoemission spectroscopic measurements corroborate an incremental rise in the density of states at the valence edge, the overlap of valence states due to doping, and the presence of distinct spin–orbit splitting and coupling in manganese-doping (Au7Mn) compared to gold clusters (Au8), originating from the relativistic effect resulted in a semiconducting property. The work function dependent current–voltage characteristics in metal–semiconductor configuration show Ohmic and Schottky behaviors assorting p-type carriers in Au7Mn in contrast to the n-type Au8 and are presenting an atomic cluster based fast electronic device.

Zn(II)-based mechanically flexible metallosupramolecular network: Investigating rheology, morphology, anti-bacterial effect and semiconducting device performances

Synthesis of supramolecular Zn(II)-metallogel of succinic acid with N,N′-dimethyl formamide (DMF) solvent has been explored in this present study. Succinic acid is used as a low molecular weight gelator (LMWG) and DMF acts as a metallogel-immobilized solvent-media. Mechanical flexibility, viscous, and elastic behaviours of the metallogel are characterized by exhaustive rheological experiments. Different rheological parameters like storage modulus (G′) and loss modulus (G″) are evaluated for certain regions of shear strain and angular frequency. The morphological decoration of xerogel material obtained from Zn(II)-based metallosupramolecular gel (i.e., Zn-Succinic) has been visualized through field emission scanning electron microscope (FESEM). Energy dispersive X-ray analysis (EDX) verifies the active involvement of metallogel-forming chemical constituents. The flexible metallosupramolecular scaffold-construction strategy has been unveiled through infrared spectroscopic data and ESI-Mass investigations. The antibacterial potency of Zn(II)-directed metallogel has also been verified against several Gram-positive bacteria (i.e., Bacillus cereus (ATCC 13061), Bacillus subtilis (MTCC 121), Listeria monocytogenes (MTCC 657), Staphylococcus aureus (MTCC 96)), and two Gram-negative bacterial strains (i.e., Salmonella typhimurium (MTCC 98) and Escherichia coli (MTCC 1667)). Even, Zn-Succinic metallogel exhibits Schottky diode behaviour with a significant non-linear rectifying nature in I-V curve, proving the semiconducting diode features with electrical parameters.

Barrow’s nonlinear charged anti-de Sitter black hole and stability

As we know, the horizon area of a black hole will increase when it absorbs matter. Based on Barrow’s concept of a fractal black hole horizon, it has been proposed (Phys Lett B 831:137181, 2022) that for a spherically fractal structure, the minimum increase in the horizon area is the area of the smallest bubble sphere. The corresponding black hole entropy is of a logarithmic form, which is similar to that of Boltzmann entropy under a certain condition. Based on this, we re-derive the entropy of Barrow’s Einstein–power-Yang–Mills (EPYM) anti-de Sitter (AdS) black hole, and calculate its temperature and heat capacity. There exists an interesting phenomenon wherein the ratio between Barrow’s temperature and the Hawking temperature of the EPYM AdS black hole is fully consistent with that of other Schwarzschild-like black holes. The Barrow and Hawking temperatures within a certain range of Λ are found to increase monotonically, and the corresponding heat capacities are all positive, which means that these black holes are thermodynamically stable. In addition, for Barrow’s EPYM AdS black hole, its heat capacity has a Schottky anomaly-like behavior, which may reflect the existence of a discrete energy level and microscopic degrees of freedom.

Experimental, theoretical and numerical simulation-based investigations on the fabricated Cu2ZnSn thin-film-based Schottky diodes with enhanced electron transport for solar cell

Copper-zinc-tin Cu2ZnSn (CZT) thin films are promising materials for solar cell applications. This thin film was deposited on a fluorine-doped tin oxide (FTO) using an electrochemical deposition hierarchy. X-ray diffraction of thin-film studies confirms the variation in the structural orientation of CZT on the FTO surface. As the pH of the solution is increased, the nature of the CZT thin-film aggregate changes from a fern-like leaf CZT dendrite crystal to a disk pattern. The FE-SEM surface micrograph shows the dendrite fern leaf and sharp edge disks. The 2-D diffusion limitation aggregation under slippery conditions for ternary thin films was performed for the first time. The simulation showed that by changing the diffusing species, the sticking probability was responsible for the pH-dependent morphological change. Convincingly, diffusion-limited aggregation (DLA) simulations confirm that the initial structure of copper is responsible for the final structure of the CZT thin films. An experimental simulation with pH as a controlled parameter revealed phase transition in CZT thin films. The top and back contact of Ag-CZT thin films based on Schottky behavior give a better electronic mechanism in superstrate and substrate solar cells.

Comparison of Electrical Conductivity and Schottky Behavior of 4‐[2‐(9‐anthryl)vinyl]pyridine Based Two 1D Coordination Polymers of Zn(II) and Cd(II)

AbstractWith the increase in demand of electronic devices in the modern civilization, research in material science is being projected to grow in faster rate. In this facet, coordination polymer (CP) based electronic device is one of the promising candidates to the material researchers. Herein, two new Zn(II) and Cd(II) based one‐dimensional (1D) CPs, denoted as [Zn(4‐avp)2(5‐nip)] ⋅ (solvent)x (1) and [Cd(4‐avp)(5‐nip)(CH3OH)] (2) have been synthesized using relatively less explored highly conjugated polycyclic aromatic hydrocarbon (PAH) based monodentate ligand, 4‐[2‐(9‐anthryl)vinyl]pyridine (4‐avp) and bidentate linker 5‐nitroisophthalic acid (H25‐nip). In this instance, the CP 1 creates 1D chain polymer, while CP 2 is made up with 1D ladder polymer. It is interesting to note that both the CPs exhibit semiconducting nature and generate metal‐semiconductor (MS) junction Schottky barrier diodes (SBDs). However, Cd‐based CP 2 shows higher charge transport as compared to Zn‐CP 1, which could be due to stronger π⋅⋅⋅π contacts as well as larger size of Cd metal in CP 2. The experimental results are well corroborated with theoretical density of states (DOS) calculations.

Titanium Silicide: A Promising Candidate of Recombination Layer for Perovskite/Tunnel Oxide Passivated Contact Silicon Two-Terminal Tandem Solar Cells.

This study proposes a titanium silicide (TiSi2) recombination layer for perovskite/tunnel oxide passivated contact (TOPCon) 2-T tandem solar cells as an alternative to conventional transparent conductive oxide (TCO)-based recombination layers. TiSi2 was formed while TiO2 was made by oxidizing a Ti film deposited on the p+-Si layer. The reaction formation mechanism was proposed based on the diffusion theory supported by experimental results. The optical and electrical properties of the TiSi2 layer were optimized by controlling the initial Ti thicknesses (5-100 nm). With the initial Ti of 50 nm, the lowest reflectance and highly ohmic contact between the TiO2 and p+-Si layers with a contact resistivity of 161.48 mΩ·cm2 were obtained. In contrast, the TCO interlayer shows Schottky behavior with much higher contact resistivities. As the recombination layer of TiSi2 and the electron transport layer of TiO2 are formed simultaneously, the process steps become simpler. Finally, the MAPbI3/TOPCon tandem device yielded an efficiency of 16.23%, marking the first reported efficiency for a device including a silicide-based interlayer.

Thermal annealing effect on phase evolution, physical properties of DC sputtered copper oxide thin films and transport behavior of ITO/CuO/Al Schottky diodes

Herein, we report on the post-annealing temperature effect on the transport behavior of p-CuO/Al Schottky barrier diodes. In addition, the transformation of phase from Cu4O3 to CuO phase was studied. Copper oxide thin films were grown on soda lime glass substrates, and post-annealing temperature's influence on the films’ structural, chemical, morphological, and electrical characteristics was comprehensively examined. X-ray diffraction study revealed the development of polycrystalline tenorite phase (CuO) on annealing. Raman analysis also confirmed the formation of the tenorite phase (CuO) at higher annealing temperatures (400 °C and 500 °C). XPS study revealed the occurrence of the Cu4O3 phase for room temperature deposited sample and CuO phase at the higher annealing temperature. Using current–voltage analysis, the Chueng model, and the thermoelectric emission model, the Schottky behavior between the metal and semiconductor were investigated. The fabricated diode showed a rectification ratio of 103 at ± 2 V, with the barrier height ranging from 0.84 to 1.12 eV due to different annealing treatments. The attributes of the power law were employed to elucidate space charge-limited conduction and the process of tunneling across the density of interface traps in p-CuO/Al Schottky diodes. This study provides valuable insights into the behavior of the p-CuO/Al Schottky junction, enhancing our understanding of its characteristics.

Fabrication of TiO2 nanoparticles/porous-silicon heterostructure photodetector for UV detection

TiO2 nanoparticles/porous-silicon heterostructure (TiO2-NPs/P-Si) was successfully synthesized using laser-assisted chemical bath deposition (LACBD). We employed a laser of 465 nm in wavelength, output power of 1 W, and 20 min deposition time to grow TiO2 nanoparticles on porous silicon. The TiO2-NPs/p-Si films properties were characterized by using FESEM, EDX, XRD, and UV-Vis. The TiO2-NPs/P-Si/Ag photodetector device performance were examined by Keithley 2400. The I-V curve of the device was tested in dark and with UV light of 365 nm wavelength conditions. It’s I-V behavior shows a Schottky behavior in the range of − 5 V and 5 V, with strong responsiveness and excellent performance. When the device is exposed to UV light, the channel current increases drastically by 183% at + 5 V, giving rise to a pronounced photoresponse. Under UV light, the current was observed to rose from − 3.5 × 10−5 A to − 3.0 × 10−5 A at − 5 V reversed bias voltage. The current increases immensely from 1.5 × 10−5 A to 3.5 × 10−4 A at +5 V forward bias voltage. For the I-t behavior, bias voltages of 1.5 V, 3 V, 4.5 V and 6 V were used and the device responsivity at these voltages were calculated to be 0.15e-3A/W, 1.59e-3A/W, 2.05e-3A/W and 2.06e-3A/W, demonstrating a great sensitivity of 558, 1160, 758 and 458 respectively. Our findings proved that TiO2 np/p-Si/Ag based photodetector could be fabricated using inexpensive, quick, and simple LACBD and yielded an excellent electrical response and sensitivity for UV photodetection applications.

Low-resistivity Ohmic contacts of Ti/Al on few-layered 1T'-MoTe2/2H-MoTe2 heterojunctions grown by chemical vapor deposition.

This study explores the phase-controlled growth of few-layered 2H-MoTe2, 1T'-MoTe2, and 2H-/1T'-MoTe2 heterostructures and their impacts on metal contact properties. Cold-wall chemical vapor deposition (CW-CVD) with varying growth rates of MoOx and reaction temperatures with Te vapors enabled the growth of continuous thin films of either 1T'-MoTe2 or 2H-MoTe2 phases on two-inch sapphire substrates. This methodology facilitates the meticulous optimization of chemical vapor deposition (CVD) parameters, enabling the realization of phase-controlled growth of few-layered MoTe2 thin films and their subsequent heterostructures. The study further investigates the influence of a 1T'-MoTe2 intermediate layer on the electrical properties of metal contacts on few-layered 2H-MoTe2. Bi-layer Ti/Al contacts directly deposited on 2H-MoTe2 exhibited Schottky behavior, indicating inefficient carrier transport. However, introducing a few-layered 1T'-MoTe2 intermediate layer between the metal and 2H-MoTe2 layers improved the contact characteristics significantly. The resulting Al/Ti/1T'-MoTe2/2H-MoTe2 contact scheme demonstrates Ohmic behavior with a specific contact resistance of around 1.7 × 10-4 Ω cm2. This substantial improvement is attributed to the high carrier concentration of the 1T'-MoTe2 intermediate layer which could be attributed tentatively to the increased tunneling events across the van der Waals gap and enhancing carrier transport between the metal and 2H-MoTe2.

Current–voltage characteristics in single layer SrIrO3 films deposited on LaAlO3(100) substrate

Here, we investigate the structural and electrical properties on SrIrO3 films grown on LaAlO3 (100) substrate with varying thickness (18, 25 and 40 nm). The x-ray diffraction shows good quality epitaxial films without any chemical impurity. The out-of-plane lattice parameter increases with the film thickness. All the films show a semiconducting behavior where the resistivity increases with increasing thickness. Our analysis shows at high temperature the charge conduction mechanism follows Mott’s two-dimensional variable-range-hopping model. Detailed current–voltage (I–V) measurements show a linear Ohmic behavior at room temperature, however, a prominent deviation from linearity has been observed at low temperatures where the exponent n () increases with decreasing temperature, reaching 1.5 at low temperature. Analysis of I–V data indicates that the charge conduction has dominant contribution of Poole–Frenkel mechanism rather than Schottky behavior. This evolution of charge transport with temperature is quite intriguing which may be related to the development of low temperature magnetism in films of SrIrO3.

Non-alloyed ohmic contacts to (010) β -Ga2O3 with low contact resistance

Low resistance non-alloyed ohmic contacts are realized by a metal-first process on homoepitaxial, heavily n+ doped (010) β-Ga2O3. The resulting contacts have a contact resistance (Rc) as low as 0.23 Ω-mm on an as-grown sample and exhibit nearly linear ohmic behavior even without a post-metallization anneal. The metal-first process was applied to form non-alloyed contacts on n+ (010) β-Ga2O3 grown by metal-organic chemical vapor deposition (MOCVD) as well as suboxide molecular beam epitaxy. Identical contacts fabricated on similar MOCVD samples by conventional liftoff processing exhibit highly rectifying Schottky behavior. Re-processing using the metal-first process after removal of the poor contacts by conventional methods does not improve the contacts; however, addition of a Ga-flux polishing step followed by re-processing using a metal-first process again results in low resistance, nearly linear ohmic contacts. The liftoff process, therefore, does not reliably render nearly linear ohmic behavior in non-alloyed contacts. Furthermore, no interface contamination was detected by x-ray photoelectron spectroscopy. This suggests that during the initial liftoff processing, a detrimental layer may form at the interface, likely modification of the Ga2O3 surface, that is not removable during the contact removal process but that can be removed by Ga-flux polishing.

Electrical Activity and Extremes of Individual Suspended ZnO Nanowires for 3D Nanoelectronic Applications.

We explored the electrical activity and extremes inside individual suspended zinc oxide (ZnO) nanowires (NWs) (diameter: 50-550 nm, length: 5-50 μm) subjected to high forward bias-induced Joule heating using two-terminal current-voltage measurements. NWs were isolated using a reproducible nanometrology technique, employing a nanomanipulator inside a scanning electron microscope. Schottky behavior is observed between installed tips and ZnO NW. The suspended ZnO NWs exhibited an average electrical resistivity ρ (approximately 2.3 × 10-2 Ω cm) and a high electron density n (exceeding 1.89 × 1018 cm-3), comparable to that of InP NWs, GaN NWs, and InAs NWs (1018∼1019 cm-3), suggesting the potential to drive advancements in high-performance NW devices. A maximum breakdown current density (JBD) of ∼0.14 MA/cm2 and a maximum breakdown power density (PBD) of 6.93 mW/μm3 were obtained, both of which are higher than substrate-bound ZnO NWs and consistent with previously reported results obtained from probed ZnO NWs grown vertically on the substrate. Moreover, we discovered that NWs experienced thermal breakdown due to Joule heating and exploited this breakdown mechanism to further investigate the temperature distribution along the ZnO NWs, as well as its dependence on the electrical properties and thermal conductance of contact electrodes. Thermal conductance was determined to be ∼0.4 nW K-1 and ∼1.66 pW K-1 at the tungsten(W)-ZnO NW and platinum(Pt)-ZnO NW contacts, respectively. In addition, we measured the elastic modulus (130-171 GPa), which closely approximated bulk values. We also estimated the nanoindentation hardness to be between 5 and 10 GPa. This work provides valuable insights into the electrical activity and extreme mechanisms, thus providing a better understanding of the potentials and limitations associated with utilizing suspended NWs in 3D nanodevices.

Investigation and Characterization of Graphene/Al, ZnO/Al and Al/Graphene/ZnO Contacts

In this paper, investigation has been made on the electrical properties of graphene/Al contact, ZnO/Al contact and Al/graphene/ZnO contacts in detail. Al metallization is considered, and it is performed via thermal vacuum coating technique under strict monitoring of the rate of thickness of the metal. Spin coating method and shadow masking are done for depositing fabricated graphene and ZnO on the thin film. Comparative analysis has been made on the parameters like saturation current, Barrier height and ideality factors which are calculated using Schottky barrier height (SBH) method. I–V characteristics are analyzed using the key‐sight B2029A semiconductor parameter analyzer. It is seen that the ZnO/Al contact has more ideality factor nearly 0.059 and exhibits Schottky behavior. Meanwhile, maximum saturation current is obtained for Graphene/Al contact whereas maximum barrier height is for ZnO/Al contact. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Investigating various metal contacts for p-type delafossite α-CuGaO2 to fabricate ultraviolet photodetector

Delafossite semiconductors have attracted substantial attention in the field of electro-optics owing to their unique properties and availability of p-type materials that are applicable for solar cells, photocatalysts, photodetectors (PDs) and p-type transparent conductive oxides (TCOs). The CuGaO2 (CGO), as one of the most promising p-type delafossite materials, has appealing electrical and optical properties. In this work, we are able to synthesize CGO with different phases by adopting solid-state reaction route using sputtering followed by heat treatment at different temperatures. By examining the structural properties of CGO thin films, we found that the pure delafossite phase appears at the annealing temperature of 900 °C. While at lower temperatures, delafossite phase can be observed, but along with spinel phase. Furthermore, their structural and physical characterizations indicate an improvement of material-quality at temperatures higher than 600 °C. Thereafter, we fabricated a CGO-based ultraviolet-PD (UV-PD) with a metal–semiconductor-metal (MSM) configuration which exhibits a remarkable performance compared to the other CGO-based UV-PDs and have also investigated the effect of metal contacts on the device performance. We demonstrate that UV-PD with the employment of Cu as the electrical contact shows a Schottky behavior with a responsivity of 29 mA/W with a short response time of 1.8 and 5.9 s for rise and decay times, respectively. In contrast, the UV-PD with Ag electrode has shown an improved responsivity of about 85 mA/W with a slower rise/decay time of 12.2/12.8 s. Our work sheds light on the development of p-type delafossite semiconductor for possible optoelectronics application of the future.

Schottky contact of nano-BiOx thin film synthesized galvanostatically on stainless steel in acetonitrile

In this study, the nanosized-BiOx thin film (mostly Bi2O3 with a trace amount of Bi2O5) is electrochemically synthesized on stainless steel (SS) surface at room temperature. The coating process is carried out using the galvanostatic pulse deposition method in an acetonitrile solution containing bismuth tetrafluoroborate, tartaric acid, tetrabutylammonium hydroxide, and tetrabutylammonium tetrafluoroborate. The structural and morphological characterizations of thin film are performed by XRD, XPS, SEM-EDX, and AFM techniques. Accordingly, α- and δ-Bi2O3-based coating with oxygen vacancies contains a small amount of Bi2O5 on the SS surface. The BiOx thin film exhibits a rough surface with many nano-sized hills homogeneously distributed. Electrical characterization is conducted with electrochemical impedance spectroscopy, current-voltage, and Hall effect measurements. The pseudoresistance with the most drastic change increases with rising potential and decreases again after reaching its maximum value at the open circuit potential. It could be inferred that the composition (oxidation states or oxygen deficiency) of the Bi2O3-based film varies according to the applied potential. The n-type Schottky behavior is observed at the SS/BiOx interface. Furthermore, the n-type SS/BiOx-based Schottky diode tested for endurance shows significant stability over 200 cycles.

In–Ga–Zn–O memristor with double layers of different oxygen vacancy densities and long-term memory towards neuromorphic applications

An In–Ga–Zn–O (IGZO) memristor with double layers of different oxygen vacancy (VO) densities has been developed, and long-term memory towards neuromorphic applications has been confirmed. The IGZO layer of the higher VO density functions as a pseudo electrode to avoid the Schottky behavior, whereas that of the lower VO density functions as a conductance change layer. The long-term potentiation and long-term depression are observed based on the memristor characteristic by applying pulse voltages, which demonstrates the future possibility towards neuromorphic applications.

Temperature-dependent study of the fabricated ZnS/p-Si heterojunction

In the present work, ZnS thin film was deposited onto a p-type Si-substrate using the chemical bath deposition method, and subsequently Ag/n-ZnS/p-Si/Ag heterojunction device was fabricated to investigate its diode parameters in the temperature range of 0–60 °C. Cubic zinc blende phase of the prepared ZnS thin film was confirmed using grazing incidence X-ray diffraction (GIXRD); Scherrer analysis revealed a lower limit of crystallite size as 2.4 nm. Scanning electron microscopy (SEM) revealed the surface morphology of the prepared ZnS thin film, which exhibited good homogeneity and density. UV–Visible absorption spectroscopy revealed the good UV-region absorbance and visible-region transmittance of the deposited ZnS thin film. The corresponding energy band gap was obtained from Tauc analysis and found to be 3.88eV. Photoluminescent emission (PLE) spectroscopy showed the defect mediated radiative transitions in the deposited ZnS thin film. Current-voltage (I–V) measurements of the fabricated heterojunction device exhibited Schottky diode behaviour. Diode parameters of reverse saturation current, Schottky barrier height, ideality factor and series resistance were obtained from the I–V measurements in the temperature range of 0–60 °C; barrier height was obtained in the range of 0.87–0.74eV, and ideality factor was obtained close to unity for I–V measurements made at 30 °C and 60 °C.

Electrical characteristics of (AgNPs-PVA)-based Schottky diode and its application as a low-voltage varistor devices

In this report, we studied the influence of silver nanoparticles (AgNPs) on the electrical conductivity of Polyvinyl Alcohol (PVA) as a semiconductor nanocomposites active layer. Here, the Schottky junction is constructed by mechanically pressing a copper (Cu) electrode onto a AgNPs-PVA nanocomposite, which shows rectification behavior at room temperature. The synthesis of silver nanoparticles (AgNPs) was achieved by the physical reduction of silver nitrate using an ultraviolet lamp. The nanocomposite films were created using a casting technique. An ultraviolet spectrophotometer (UV–vis), which displayed maximum absorbance at 430 nm, was used to confirm the synthesis of AgNPs and carry out the optical band gap. The charge carrier transport properties of AgNPs-PVA film were investigated by using impedance spectroscopy and I–V measurements. Then, AC impedance analysis was used to determine grain and grain boundary resistances; current-voltage analysis enabled the barrier height (Φ) to be determined. Moreover, the metal/semiconductor (Cu/AgNPs-PVA) Schottky barrier was confirmed as an equivalent circuit model via the Nyquist plot. Based on thermoionic emission theory, the characteristic I–V induced rectifying Schottky behavior can be understood. Moreover, the AgNPs-PVA nanocomposite exhibited hysteresis behavior under multiple repetitive measurements. For low voltage varistor devices, the nonlinear behavior may be completely utilized.