Properties Of Schottky Diodes Research Articles

Role of defects in tailoring the structural, electrical and optical properties of Schottky diodes based on GaAsBi alloy through gamma radiation

This work provides an extensive study of the influence of γ-rays on structural, electrical, and optical characteristics of GaAsBi Schottky diodes fabricated through Molecular Beam Epitaxy (MBE) on GaAs substrates. An important finding is the direct correlation observed between the radiation dose and the consequent increase in the turn-on voltage of the devices. X-ray diffraction (XRD) showed that only phases related to the GaAs and GaAs1-xBix layers were observed. Raman spectroscopy proved to be a powerful tool to elucidate the effects of ionizing radiation on GaAsBi samples. From the results of electrical measurements, such as current density-voltage, the characteristic parameters of the devices improved as a function of the radiation dose. Conversely, the Capacitance-Voltage (C–V) characteristics indicated a rise in the concentration of free carriers in all irradiated samples, suggesting an enhancement in the performance of the diodes. Assessment through Deep Level Transient Spectroscopy (DLTS) further revealed a reduction in the number of electrically active traps following irradiation. Consequently, the findings presented here highlight the potential improvements in diode performance resulting from sample irradiation. Upon subjecting the samples to irradiation doses of 50 kGys and 100 kGys, we identified the presence of three and two electron traps, respectively. This differs from the unirradiated diodes, which displayed four electron traps. Interestingly, the photoluminescence intensity of the main peak exhibited an increment with increasing irradiation dose. This observation implies an enhancement in the optical characteristic, as well as annihilation/contribution of Bi-related traps. These findings corroborate the electrical results obtained in our study. Finally, the Raman results showed that the decrease in the lifetime of the photoexcited carriers leads to a higher recombination rate which in turn leads to a higher photoluminescence (PL) intensity after radiation.

Influence of deposition pressure of elemental Sn on structural, optical, electrical and schottky diode properties of SnS thin films grown by two-stage method

Influence of deposition pressure of elemental Sn on structural, optical, electrical and schottky diode properties of SnS thin films grown by two-stage method

Effect of Schottky annealing temperature on reverse leakage current of 6500 V 4H-SiC JBS diodes

Annealing treatment has an important effect on the electrical properties of Schottky diodes. In this paper, the effect of Schottky annealing temperature on reverse leakage current of 6500 V 4H-SiC JBS diodes was studied. The reverse leakage current of the diode annealed at 500 °C is higher than that of the diode annealed at 450 °C. This is because the Schottky barrier height of the diode annealed at 500 °C is decreased by 0.08 eV, which leads to a large reverse leakage current. Meanwhile, the Schottky barrier height of the diode annealed at 500 °C is decreased more significantly with the increase of measurement temperature, therefore the reverse leakage current increases significantly.

Electrical and optical properties of Schottky diodes fabricated by electrodeposition of Ni films on n-GaAs

In this paper, we report electrical and optical characteristics of the Schottky diodes fabricated by electrodeposition of nickel onto n -GaAs substrate from 0.125 M NiSO 4 + 0.25 M H 3 BO 3 + 0.25 M Na 2 SO 4 solution. The electrodeposition was performed at room temperature and at − 1.5 V vs. SCE. Electrical and optical properties were measured in the temperature range of 200–360 K. Dark and light current-voltage ( I-V ) characteristics were investigated. Ideality factor, n and zero-bias barrier height, ϕ b were calculated and found to be almost constant in this temperature range. For room temperature, these values were obtained as 1.05 and 0.70 eV, respectively. Illuminated I-V characteristics were also investigated and they showed that the fabricated device could operate in photovoltaic regime. Open-circuit voltage, V oc was found to be 0.24 V for the diode under 20 mW/cm 2 illumination. • Good light sensitivity is achieved by electrodeposition. • Room temperature n and ϕ b values are 1.05 and 0.70 eV, respectively. • Electrodeposited Ni/ n -GaAs Schottky diode can operate in photovoltaic regime.

Research implementing different dopants (M = Al, Sn, and Eu) on the properties of Schottky diodes with structure TCO/CdS/C and TCO/CdS:M/C

A metal-semiconductor interface is an integral part of numerous electronic devices such as Schottky barrier diodes, photodetectors, photovoltaic detectors, photoelectric converters for UV radiation, among others. On the other hand, semiconductor thin films of cadmium sulfide have been applied to several electronic devices. This study presents the synthesis of semiconductor thin films of pure cadmium sulfide and those doped with Al, Sn, and Eu by a chemical bath deposition technique. XRD, SEM, EDS, XPS, UV-Vis spectroscopy, I-V, and photocurrent measurement analyzed these semiconductor thin films. Afterwards, the doped and undoped CdS thin films were applied to the manufacture of Schottky diodes. The doped CdS thin films reveals differences in the size of the crystallites, which decreased by 5.7%, 11.5%, and 60.1% after doping with aluminum, tin, and europium, respectively. The CdS thin films show morphological differences, decreasing grain size by 5.3% in the case of tin doping and increasing by 21.9% with aluminum and 32.6% after being doped with europium. Additionally, the energy bandgap of the doped CdS thin films show a blue shift, except when doped with Eu, which shows a red shift. This enables the design of window layers by choosing the suitable dopant of CdS. The effect of the CdS doping on the electrical photoresponse of the Schottky diodes was also analyzed. Due to the incorporation of dopants, the photoresponse of the aluminum-doped CdS Schottky diodes improved by 176% compared to its undoped counterpart and by up to 493% with other reports in the literature. The Schottky diodes manufactured in this work show variation in height of the potential barrier, increasing by 6% in the case of aluminum doping and decreasing by 5% and 25% after being doped with europium and tin respectively. These results demonstrated the beneficial impact of dopants on the characteristics of the CdS-based Schottky diodes and elaborated photodiodes, exhibiting an impressive enhancement in their photoresponse, in the potential barrier reached for photosensitivity and in the energy band gap value. Overall, our extensive study reveals that there is great potential in the design of affordable multifunctional optoelectronic devices.

Investigation of Schottky barrier height using area as parameter: Effect of hydrogen peroxide treatment on electrical optical properties of Schottky diode

RF sputtered 25 nm ZnO thin film surface treated with H2O2 has produced the Schottky diodes of improved electrical and optical properties. The enhancement is associated with adsorbed and introduced oxygen at the film's surface and in bulk while H2O2 treatment as revealed by the XPS analysis. Further, H2O2 treatment also has improved the ZnO thin film's surface morphology, crystal structure, and optical properties studied by XRD, SEM, and PL measurement. The experimentally measured energy band gap is compared with density functional theory computation-based result to find the possible cause behind the change in edge excitation energy band after treatment. Besides, an alternative method by considering the Schottky diode area as a parameter is introduced to calculate barrier height. The five diodes average barrier height, calculated by the conventional Schottky model, was lower than the barrier height obtained by this proposed method. This result is obtained for the diodes fabricated on the nontreated and treated sample. The conventional and proposed methods showed Schottky diodes potential barrier lowering under UV illumination, and it was associated with the change in carrier density and desorption of adsorbed oxygen on the ZnO surface. The treated surface's low conductivity and high oxygen concentration governed the superior UV detection capability of Schottky diodes fabricated on it. The literature demonstrates many similar studies for large thicknesses of ZnO 150–1000 nm but not on ultra-thin (25 nm) ZnO film, even though the UV light can penetrate ZnO approximately to this depth.

Characterization and evaluation of current transport properties of power SiC Schottky diode

This paper presents the characterization and evaluation of current transport properties of power SiC Schottky diode. The evaluation of the main Schottky diode properties is based on the proposed advanced model. This model allows assessing the effect of particular current transport mechanisms with high accuracy. The presence and influence of tunneling current in I-V characteristics are evident, mainly for low temperatures. Unlike previously published results, the proposed model provides areasonable slight decrease of Schottky barrier height with increasing temperature due to the narrowing of the energy bandgap. The results and model are validated by finite element method (FEM) electrophysical simulations. Evaluated parameters of SiC Schottky diode, such as Schottky barrier height of 1.28 eV and Richardson constant of 1.46 × 106 Am−2K−2 are in good agreement with recent research and FEM simulations.

Effect of Ag decoration on the photodetection of catalyst-free synthesized vertically oriented SiOx NW arrays

This study reports a catalyst-free synthesis of silver (Ag) nanoparticles (NPs) decorated SiOx nanowire (NW) arrays on silicon (Si) substrates by employing the GLAD technique. A huge enhancement in optical absorption was seen all over the visible spectrum as compared to bare SiOx NW arrays. Photoluminescence measurement showed many defect-related emissions in the UV-vis region. The successful growth of vertically oriented Ag decorated SiOx NWs on Si substrate was manifested through the field emission gun scanning electron microscopy (FEGSEM) with energy dispersive X-ray spectroscopy (EDS) analysis. The transmission electron microscope analysis revealed the crystalline and amorphous nature of Ag NPs and SiOx NWs respectively. Through Tauc plot, a low bandgap of 1.9 eV was obtained after decorating the bare SiOx NWs with Ag NPs. The device successfully exhibited properties of Schottky diode through its rectifying behaviour. Most interestingly, very low turn-on voltages of 1.4 V and 1.8 V were obtained for Ag decorated SiOx NWs corresponding to the white light and dark conditions as compared to bare SiOx NWs whose turn–on voltages were 1.8 V and 2.8 V respectively. The Ag decorated SiOx NW detector gave a low ideality factor of only 10.27 as compared to 20.99 for bare SiOx NW detector. At −5 V, the device showed a responsivity of 1.54 A/W, detectivity of 2.12 × 1010 Jones and EQE of 5.17 × 102 %. Moreover, seven-fold enhancement of photocurrent to dark current contrast ratio was obtained for the Ag decorated SiOx NW device at -0.2 V accompanied with a fast response of 0.12 s (rise time) and 0.11 s (fall time), thus expanding its usability.

Fabrications of Hetero-Junction Schottky Diodes by Electrodeposition of Nano-Structured CuInSe2 Materials Using Different Upper Electrodes

In this study, CuInSe2 (CIS) films (CIS-TFs) and nanorods (CIS-NRs) were successfully deposited on Mo/glass and p+-silicon (p+-Si) using an electrodeposition method. Anodic aluminum oxide (AAO) was used as the template when the CIS-NRs were deposited. Pt, indium tin oxide (ITO), and Ag were deposited as the upper electrodes using a sputtering method to form the hetero-junction devices of Pt/CIS-NRs/p+-Si, ITO/CIS-NRs/p+-Si, ITO/CIS-TF/Mo/glass, and Ag/CIS-NRs/p+-Si, respectively. When p+-Si was used as the substrate, Al was deposited on p+-Si to form negative electrodes for the devices of Pt/CIS-NRs/p+-Si, ITO/CIS-NRs/p+-Si, and Ag/CIS-NRs/p+-Si. The current–voltage properties of all the hetero-junction devices were measured and we found that the hetero-junction of ITO/CIS-NRs/p+-Si, ITO/CIS-TF/Mo/glass, and Ag/CIS-NRs/p+-Si devices revealed the properties of Schottky diodes but the hetero-junction device of Pt/CIS-NRs/p+-Si device did not. The reason for the cause of the differences between these hetero-junction devices was investigated for this study.

AC electrical properties of Schottky diode based on nanocrystalline silicon thin films

Thin film of hydrogenated amorphous silicon has been deposited with plasma enhanced chemical vapor deposition technique. The obtained samples were thermally annealed at 700°C and 900°C to get nanocrystalline silicon. The energy band gap has been determined using the Tauc's model for indirect transitions. The band gap of the layer increases from 1.75eV to 2.1 eV as the annealing temperature increases and indicates a structure change from amorphous to nanocrystalline phase. The electrical characterization of the Au/nc-Si:H Schottky diodes was performed using conductance-voltage-frequency (G/ω-V) and capacitance-voltage (C–V) measurements. The presence of a peak in C–V characteristic and the increase of capacitance with decreasing frequency is a signature of a continuous distribution of interface states. According to characteristic analysis, the amorphous region and nanocrystalline phase dominated over distinguishable frequency scales. The response of the former one emerges at low frequencies whereas the other stands out at extremely high frequencies.

Effect of (Ce, Al) co-doped ZnO thin films on the Schottky diode properties fabricated using the sol-gel spin coating

In this work, Schottky diodes based on undoped and (Ce, Al) co-doped ZnO thin films have been fabricated using the sol-gel spin coating. The effect of (Ce, Al) co-doped ZnO films on the structural and optical properties has been studied, and the electrical characteristic of the fabricated Schottky diode devices are investigated. X-ray diffraction and field emission scanning electron microscopy are used to study the crystalline structure and surface morphology, respectively. Room temperature Raman spectroscopy showed that the intensity of the dominant E2 high peak decreased after doping. The photoluminescence studies at room temperature showed that the intensity of the UV and the visible emission peak decreased after doping. UV-vis spectroscopy measurements at room temperature showed a decrease in the optical band gap after doping compared to undoped ZnO thin films. The I–V characteristics of fabricated Schottky diodes manifest good device behaviour at higher levels of doping (7.0 at.%) with an ideality factor of 2.40, the barrier height of 0.77 eV and series resistance of 262 Ω. The maximum rectification ratio was found to be nearly 105 at 7.0 at.%. Moreover, the electrical properties of the Schottky diode devices analyzed with Cheung-Cheung function revealed that the Schottky diode parameters were higher compared to those obtained from the conventional thermionic emission theory. Furthermore, the free electron carrier concentration for the doped samples was found to be lower compared with undoped ZnO films.

Structural, optical and Schottky diode properties of Cu2ZnSnS4 thin films grown by two-stage method

CZTS thin film was prepared by a two-stage process comprising sputter deposition of metallic Cu, Zn, and Sn layers followed annealing treatment of the metallic precursors in a sulfur atmosphere at 560 °C for 3 min. The CZTS thin film was investigated in the way of structural, optical and electrical properties. The XRD pattern of Cu-poor and Zn-rich CZTS thin film was dominated by characteristic peaks of kesterite CZTS planes. Raman spectra of the film ensured formation of kesterite CZTS phase and displayed formation of CTS and ZnS phases. Dense and polycrystalline surface features were observed in SEM images of CZTS thin film. Band–band transitions was not observed due to the probable concentration of deep acceptor levels in this material. The diode parameters of Mo/CZTS/Al structure such as ideality factor, barrier height and serial resistance were calculated employing temperature dependent I–V characteristics of Mo/CZTS/Al diode structure.

Effect of Sm doping ZnO nanorods on structural optical and electrical properties of Schottky diodes prepared by chemical bath deposition

In this study, pure and Sm doped ZnO nanorods from 0.0 to 5.5 at% were synthesized using the chemical bath deposition method at 90 °C. The effect of Sm doping of ZnO nanorods on their structural, morphology and optical properties were investigated. X-ray diffraction patterns revealed that Sm had been successfully incorporated into the ZnO lattice and no other impurities or Sm oxide phases were detected. Field emission scanning electron microscopy images showed that the growth rate of the nanorods was suppressed by Sm doping. Room temperature Raman scattering spectroscopy revealed that the relative intensity of E2(high) mode decreased and shifted slightly towards a lower wavenumber in Sm doped ZnO when compared to the undoped ZnO nanorods. The photoluminescence spectrum of as-synthesized Sm-doped samples measured at room temperature shows that the UV emission is slightly red shifted and the green-yellow emission of the visible emission is enhanced, when compared to undoped samples. Photoluminescence studies also revealed the good crystal quality of the as-synthesized samples as all sample shows strong ultraviolet and weak deep-level emission peaks. The as-synthesized samples were also characterized using X-ray photoelectron spectroscopy that revealed the presence of Zn and O in all samples and a small amount of Sm in 5.5 at% Sm doped ZnO was detected. Furthermore, the current-voltage characteristics of a fabricated Schottky diodes showed a good rectifying behavior when ZnO doped with Sm at 1.5 at%. The obtained Schottky barrier height for pure and Sm doped ZnO nanorods were 0.55 eV and 0.72 eV, respectively.

Effects of surface morphology on the optical and electrical properties of Schottky diodes of CBD deposited ZnO nanostructures

We report on effect of surface morphology on the optical and electrical properties of chemical bath deposited Zinc oxide (ZnO) nanostructures. ZnO nanostructures were deposited on the seeded conducting indium doped tin oxide substrate positioned in three different directions in the growth solution. Field emission scanning electron microscopy was used to evaluate the morphological properties of the synthesized nanostructures and revealed that the positioning of the substrate in the growth solution affects the surface morphology of the nanostructures. The optical absorbance, photoluminescence and Raman spectroscopy of the resulting nanostructures are discussed. The electrical characterization of the Schottky diode such as barrier height, ideality factor, rectification ratios, reverse saturation current and series resistance were found to depend on the nanostructures morphology. In addition, current transport mechanism in the higher forward bias of the Schottky diode was studied and space charge limited current was found to be the dominant transport mechanism in all samples.

Structural, morphological, optical and electrical properties of Schottky diodes based on CBD deposited ZnO:Cu nanorods

Undoped and copper doped zinc oxide (ZnO) nanorods have been synthesized by a simple chemical bath deposition (CBD) method at a temperature of 90 °C. Structural, morphological, optical and electrical properties of the synthesized ZnO nanorods were found to be dependent on the Cu doping percentage. X-ray diffraction (XRD) patterns revealed strong diffraction peaks of hexagonal wurtzite of ZnO, and no impurity phases from metallic zinc or copper. Scanning electron microscopy (SEM) images showed changes in diameter and shape of nanorods, where by those doped with 2 at.% and 3 at.% aggregated and became compact. Selected area electron diffraction (SAED) patterns indicates high quality, single crystalline wurtzite structure ZnO and intensities of bright spots varied with copper doping concentration. UV–visible absorption peaks of ZnO red shifted with increasing copper doping concentration. Raman studies demonstrated among others, strong and sharp E2 (low) and E2 (high) optical phonon peaks confirming crystal structure of ZnO. Current-voltage measurements based on the gold/ZnO nanorods/ITO showed good rectifying behavior of the Schottky diode. The predicted Schottky barrier height of 0.60 eV was obtained which is not far from the theoretical Schottky-Mott value of 0.80 eV.

Effect of substrate temperature on electrical properties of (Al/p-Cu3SbS3 /Mo) Schottky diodes grown by vacuum thermal evaporation

This study highlights some physical properties of Schottky diodes (Al/p-Cu3SbS3/Mo) fabricated by simple deposition of Aluminum on the front side of the Cu3SbS3 thin films. p-Cu3SbS3 were grown by by thermal evaporation method onto heated and unheated Mo substrates. The current–voltage (I–V) characteristics show the interaction between the Aluminum and p-Cu3SbS3 give a Schottky contact. The saturation currents, the ideality factors and series resistances were extracted from the experimental data. Moreover, the capacitance–voltage (C–V) characteristics reveal the values of the barrier height of the heterostructures. The Schottky diode at a substrate temperature of 150 °C showed the strongest barrier height (0.59 eV) and the lowest leakage current (1.08 × $${10^{ - 6}}{\text{A}}$$ ). In order to evaluate the conduction processes of the samples, the impedance spectroscopy technique were used. To model these results, equivalent electrical circuits were used. Finally, from the analysis of the data, we found a decrease of the entire serial resistances Rs, the parallel resistances Rp and the capacitances Cp when the increase of the temperature.

-ray detector based on n-type 4H-SiC Schottky barrier diode

Silicon carbide (SiC) is a wide band-gap, high-temperature-resistant, and radiation-resistant semiconducting material, which can be used as a radiation detector material in harsh environments such as high radiation background and high temperatures. Schottky barrier diode radiation detectors are fabricated using 100 upm-thick n-type 4H-SiC epitaxial layers for low energy -ray detection. The spectrum responses of 4H-SiC Schottky barrier detectors are investigated by irradiation of -ray from 241Am source. Schottky diodes are prepared by magnetron-sputtering 100 nm-thick nickel on epitaxial surface (Si face) to obtain Schottky contact and Ni/Au on substrate surface (C face) to obtain Ohmic back contact, respectively. Room temperature current-voltage (I-V) and capacitance-voltage (C-V) curves are measured to study the properties of Schottky diodes. Ohmic characteristic measurement shows that the Ohmic contact is formed after annealing in a temperature range of 900-1050℃, and the lowest specific contact resistivity of 2.5510-5 cm2 is obtained after annealing at 1050℃. The forward I-V curve reveals that the Schottky barrier height and the ideality factor are 1.617 eV and 1.127, respectively, indicating that the main current transportation process is the thermal electron emission. From the C-V curve, besides the net dopant concentration being inferred to be 2.9031014 cm-3, the profile of the free carrier concentration in epitaxial layer is also studied. A comparision of the reverse I-V curves of SiC Schottky diodes with different epitaxial layer thickness shows that the diode with 100 upm-thick epitaxial layer has a constant reverse leakage current when the bias voltage is less than 400 V, showing good rectification characteristics. By applying a reverse bias of 500 V, the diode has a leakage current of 2.11 nA, exhibiting a relatively high breakdown voltage. The depletion layer width of SiC detector is calculated to be 94.4 m at 500 V, indicating that the epitaxial layer is almost fully depleted. The signal of SiC detector through preamplifier displays a relatively low amplitude pulse (15 mV). A typical -ray spectrum response from SiC detector shows 9.49% (5.65 keV) energy resolution for 59.5 keV with a reverse bias of 300 V. The potential causes of poor count rate and energy resolution of fabricated detectors are analyzed in this article. The lower count rate is mainly caused by the narrow depletion layer, resulting in fewer photons deposited in sensitive region which can generate carriers. The poor energy resolution of SiC detector can be attributed to the electronic noise of read-out circuit, the pre-match amplifier circuit for detector needs to be improved, in addition, the extra defects existing in detector caused by increasing thickness of epitaxial layer can also deteriorate the detector performance.

Evaluating Work-Function and Composition of ErSix on Various Surface Orientation of Silicon

The work function of ErSiX on different surface orientation of Si was evaluated. ErSiX was formed by suppressing of the oxidation during the Si surface cleaning, Er sputtering, and silicidation annealing. Almost ideal Schottky diode properties are obtained on every surface orientation. The work function of ErSiX depends on the surface orientation and deposited Er thickness. The work function of ErSiX on Si(100) decreases and that on Si(551) increases with the increasing Er thickness. In addition, the work function ErSiX on Si(111) for the thickness less than 5 nm is constant and very low value of about 0.25 eV. These work function values depend on Si concentration in ErSiX, and it is considered that the concentration difference is caused by the lattice mismatch between ErSi2 and Si surface.

Electrophysical properties of Schottky diodes with inhomogeneous contact surface

In Cu–nSi Schottky diode (SD) with inhomogeneous contact surface at the active participation of the additional electric field (AEF) is formed a effective potential barrier height. Forward and initial reverse I–V characteristics SD are determined by the current flowing through almost the entire contact surface and is well described by the thermionic emission theory, as in the idealized homogeneous SD. In a forward and primary reverse bias the effective potential barrier height, the ideality factor (dimensionless coefficient), the contact resistance, the peripheral area and width of the contact surface, the contribution of peripheral current to the total current DS have appropriate similar values. The contribution of peripheral current to the total current SD increases with increasing reverse voltage. The second portion of the reverse I–V characteristics SD, which consists only of peripheral current is represented by a straight line in a semi-logarithmic scale. Its electrophysycal parameters are differed from that for of the first initial portion I–V characteristics SD.

Study of Electrical Properties of Schottky Diodes Fabricated on Silicon with Different Metal Layers

We have investigated the fabrication of AuxTi100−x—nSi (where x is 10; 36; 87) and PbxSb100−x—nSi (where x = 52; 70; 87) Schottky diodes and the electrical properties of AuxTi100−x—nSi (where x = 10; 36; 87) and PbxSb100−x—nSi (where x = 52; 70; 87)Schottky diodes. The Au36Ti64, Pb52Sb48 alloy film has an amorphous structure, while the other films are polycrystalline. We have determined Schottky barrier height depending on the composition and structure of the metal films and found that the barrier height is quite sensitive to the composition of the metal alloy. We show that the electrical properties of the AuxTi100−x—nS and PbxSb100−x—nSi Schottky diodes depend on the composition and structure of the metal films.