Schottky Diodes Research Articles

Mo/Au β-Ga₂O₃ Schottky Barrier Diodes With Low Turn-On Voltage and High On–Off Ratios for Low-Power Consumption Applications

Mo/Au β-Ga₂O₃ Schottky Barrier Diodes With Low Turn-On Voltage and High On–Off Ratios for Low-Power Consumption Applications

Development and Research of W-Band Multiplier Based on Schottky Barrier Diodes with Pt/Ir Contacts

Development and Research of W-Band Multiplier Based on Schottky Barrier Diodes with Pt/Ir Contacts

Etching-free pixel definition in InGaN green micro-LEDs

The traditional plasma etching process for defining micro-LED pixels could lead to significant sidewall damage. Defects near sidewall regions act as non-radiative recombination centers and paths for current leakage, significantly deteriorating device performance. In this study, we demonstrated a novel selective thermal oxidation (STO) method that allowed pixel definition without undergoing plasma damage and subsequent dielectric passivation. Thermal annealing in ambient air oxidized and reshaped the LED structure, such as p-layers and InGaN/GaN multiple quantum wells. Simultaneously, the pixel areas beneath the pre-deposited SiO2 layer were selectively and effectively protected. It was demonstrated that prolonged thermal annealing time enhanced the insulating properties of the oxide, significantly reducing LED leakage current. Furthermore, applying a thicker SiO2 protective layer minimized device resistance and boosted device efficiency effectively. Utilizing the STO method, InGaN green micro-LED arrays with 50-, 30-, and 10-µm pixel sizes were manufactured and characterized. The results indicated that after 4 h of air annealing and with a 3.5-μm SiO2 protective layer, the 10-µm pixel array exhibited leakage currents density 1.2 × 10−6 A/cm2 at −10 V voltage and a peak on-wafer external quantum efficiency of ~6.48%. This work suggests that the STO method could become an effective approach for future micro-LED manufacturing to mitigate adverse LED efficiency size effects due to the plasma etching and improve device efficiency. Micro-LEDs fabricated through the STO method can be applied to micro-displays, visible light communication, and optical interconnect-based memories. Almost planar pixel geometry will provide more possibilities for the monolithic integration of driving circuits with micro-LEDs. Moreover, the STO method is not limited to micro-LED fabrication and can be extended to design other III-nitride devices, such as photodetectors, laser diodes, high-electron-mobility transistors, and Schottky barrier diodes.

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.

Edge-Terminated AlGaN/GaN/AlGaN Multi-Quantum Well Impact Avalanche Transit Time Sources for Terahertz Wave Generation

In our pursuit of high-power terahertz (THz) wave generation, we propose innovative edge-terminated single-drift region (SDR) multi-quantum well (MQW) impact avalanche transit time (IMPATT) structures based on the AlxGa1−xN/GaN/AlxGa1−xN material system, with a fixed aluminum mole fraction of x = 0.3. Two distinct MQW diode configurations, namely p+-n junction-based and Schottky barrier diode structures, were investigated for their THz potential. To enhance reverse breakdown characteristics, we propose employing mesa etching and nitrogen ion implantation for edge termination, mitigating issues related to premature and soft breakdown. The THz performance is comprehensively evaluated through steady-state and high-frequency characterizations using a self-consistent quantum drift-diffusion (SCQDD) model. Our proposed Al0.3Ga0.7N/GaN/Al0.3Ga0.7N MQW diodes, as well as GaN-based single-drift region (SDR) and 3C-SiC/Si/3C-SiC MQW-based double-drift region (DDR) IMPATT diodes, are simulated. The Schottky barrier in the proposed diodes significantly reduces device series resistance, enhancing peak continuous wave power output to approximately 300 mW and DC to THz conversion efficiency to nearly 13% at 1.0 THz. Noise performance analysis reveals that MQW structures within the avalanche zone mitigate noise and improve overall performance. Benchmarking against state-of-the-art THz sources establishes the superiority of our proposed THz sources, highlighting their potential for advancing THz technology and its applications.

Perspective on electrically active defects in β-Ga2O3 from deep-level transient spectroscopy and first-principles calculations

The ultra-wide bandgap of gallium oxide provides a rich plethora of electrically active defects. Understanding and controlling such defects is of crucial importance in mature device processing. Deep-level transient spectroscopy is one of the most sensitive techniques for measuring electrically active defects in semiconductors and, hence, a key technique for progress toward gallium oxide-based components, including Schottky barrier diodes and field-effect transistors. However, deep-level transient spectroscopy does not provide chemical or configurational information about the defect signature and must, therefore, be combined with other experimental techniques or theoretical modeling to gain a deeper understanding of the defect physics. Here, we discuss the current status regarding the identification of electrically active defects in beta-phase gallium oxide, as observed by deep-level transient spectroscopy and supported by first-principles defect calculations based on the density functional theory. We also discuss the coordinated use of the experiment and theory as a powerful approach for studying electrically active defects and highlight some of the interesting but challenging issues related to the characterization and control of defects in this fascinating material.

Electroconductive and photoelectric properties of Pt/(100) β-Ga2O3 Schottky barrier diode based on Czochralski grown crystal

Pt/(100) β-Ga2O3 Schottky barrier diodes were fabricated using a plate cleaved from the crystal grown by Czochralski method. Their electroconductive and photoelectric characteristics were studied. The following values were obtained: the Schottky barrier height (1.69/1.62/1.74 eV), ideality coefficient (1.09/1.14), saturation current density (9.91 × 10–15 A/cm2), diode series resistance (7.98 kΩ), and net donor concentration [(1.8–2.4) × 1018 cm–3]. The diodes demonstrate a high rectification ratio of 1010 at an applied voltage of ± 1 V and a relatively low experimental value of the leakage current density ∼10–11 A/cm2. These structures are solar-blind and also capable of operating in self-powered mode. The diodes are highly sensitive to short-wave ultraviolet radiation with a wavelength λ ≤ 265 nm. The maximum values of responsivity (20.4 A/W), external quantum efficiency (1.2 × 104%), and detectivity (9.6 × 1015 Hz0.5 × cm × W–1) of diodes were registered under exposure to irradiation at λ = 210 nm and at applied voltage of −1 V. The responsivity and external quantum efficiency values in the self-powered operation mode were 12.3 A/W and 7.2 × 103%, respectively. The diodes showed low rise and decay times in self-powered operation mode for photodiode based on Ga2O3: 14 and 30 ms, respectively.

High breakdown voltage of 1.3 kV and low turn-on voltage of 0.48 V β-Ga2O3 heterojunction barrier Schottky diode with tungsten Schottky contact

Abstract β-Ga2O3 power diodes were expected to possess low turn-on voltage (Von), low reverse leakage (JR), and high blocking capability for low power losses. In this work, a low Von (0.48 V) β-Ga2O3 heterojunction barrier Schottky diode (HJBS) with Tungsten Schottky contact was achieved. Benefitting from the lateral depletion of p+-NiO to suppress JR originating from the low Schottky barrier, the blocking capability of β-Ga2O3 HJBS was enhanced. The spacing width of p+-NiO was systematically studied to reveal its modulation effect on forward and reverse characteristics. This work provides a promising strategy for improving rectifier efficiency of β-Ga2O3 diodes.

Structural and optical properties of sulfurized Cu2ZnSnS4 films grown by one step method using calcined powders for electrical properties study of Al/p-Cu2ZnSnS4 Schottky diode

Structural and optical properties of sulfurized Cu2ZnSnS4 films grown by one step method using calcined powders for electrical properties study of Al/p-Cu2ZnSnS4 Schottky diode

Research on Single-Event Burnout Reinforcement Structure of SiC MOSFET.

In this paper, the single-event burnout (SEB) and reinforcement structure of 1200 V SiC MOSFET (SG-SBD-MOSFET) with split gate and Schottky barrier diode (SBD) embedded were studied. The device structure was established using Sentaurus TCAD, and the transient current changes of single-event effect (SEE), SEB threshold voltage, as well as the regularity of electric field peak distribution transfer were studied when heavy ions were incident from different regions of the device. Based on SEE analysis of the new structural device, two reinforcement structure designs for SEB resistance were studied, namely the expansion of the P+ body contact area and the design of a multi-layer N-type interval buffer layer. Firstly, two reinforcement schemes for SEB were analyzed separately, and then comprehensive design and analysis were carried out. The results showed that the SEB threshold voltage of heavy ions incident from the N+ source region was increased by 16% when using the P+ body contact area extension alone; when the device is reinforced with a multi-layer N-type interval buffer layer alone, the SEB threshold voltage increases by 29%; the comprehensive use of the P+ body contact area expansion and a multi-layer N-type interval buffer layer reinforcement increased the SEB threshold voltage by 33%. Overall, the breakdown voltage of the reinforced device decreased from 1632.935 V to 1403.135 V, which can be seen as reducing the remaining redundant voltage to 17%. The device's performance was not significantly affected.

Frequency-dependent dielectric, electric modulus, and ac conductivity features of Au/n-Si Schottky diodes (SDs) with PVC and (PVC:Graphite/Graphene-Oxide) interlayer

To determine the interlayer effect on dielectric features and conductivity, Au/n-Si (S0), Au/PVC/p-Si (S1), and Au/PVC:Gt-GO/p-Si (S2) type SDs were grown onto the same n-Si wafer and their admittance measurements performed between 100 Hz and 1 MHz. The observed decrease in C and G/ω values as frequency increases shows that the charges at the interface-states (N ss) can easily follow ac-signal and supply an excess capacitance and conductance at lower frequencies. Using C and G/ω data at 1.5 V, the dielectric-constant (ϵ′), dielectric-loss (ϵ″), and loss-tangent (tan δ) were obtained as a function of frequency. To determine the relaxation processes in (PVC:Gt-GO) nanocomposite, complex-dielectric (M′ and M′′) formalism was also explored in the whole frequency range. The value of ac electrical conductivity (σ ac) remained independent of frequency until 0.1 MHz and then started to increase exponentially which corresponds to dc and ac conductivity. As compared to S1 and S2 with So SD, the conductivity and ϵ′ values increase due to the PVC and (PVC:Gt-GO) interlayer. The Ln(σ ac)-Ln(ω) plots were also drawn to analyze the conduction process and their slopes were found as 0.09, 0.39, and 0.58 for S0, S1, and S2 SD, respectively. These results show that the interaction and trap levels of the electron–hole pairs at lower frequencies, as well as from the well-localized relaxation mechanism at higher frequencies.

Vertical Schottky diode on (113) oriented homoepitaxial diamond

Vertical Schottky diodes were fabricated on (113) oriented diamond substrates produced from thick heavily boron doped (NA ∼ 3.5 × 1020 cm−3) diamond layers grown on HPHT-grown synthetic Ib diamond crystals. The p+-substrates were overgrown by a low doped p-epilayer whose surface layer was compensated up to the depth of 0.1 to 0.3 μm. The surface was then oxygen terminated and covered by evaporated Mo/Au Schottky contacts. The bottom ohmic contact to p+-substrate was formed by Ti/Au bi-layer. Current- and capacitance-voltage characteristics of the realized diodes were measured at temperatures ranging from 25 to 180 °C. At room temperature, the realized diodes show high forward current densities JF = 100 A/cm2 and low differential ON-state specific resistance Ron_sp = 3.7 mΩ.cm2 at forward voltage VF = 4 V and a very low leakage (JR < 10−9 A/cm2) in the blocking regime. At 180 °C, forward characteristics significantly improve (JF = 5 kA/cm2, Ron_sp = 0.2 mΩ.cm2 at VF = 4 V) while the blocking characteristics remain almost unchanged (JR = 6 × 10−8 A/cm2 at VR = 4 V). The breakdown electric field is about 3 MV/cm and the rectification ratio keeps at the level of 1011. Characteristics of realized diodes, which are fully comparable to those of Schottky-pn diodes prepared on (111) oriented boron doped diamond, confirm the suitability of (113) orientation for realization of vertical diamond power devices.

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.

Synthesis of 2D yttrium zinc oxide nanosheets via simple chemical route toward high performance Schottky diode based on large charge carriers density and photoresponsivity

Abstract Yttrium zinc oxide (Zn0.85Y0.15O) nanostructures were stoichiometrically prepared by co-precipitation method. XRD, EDX, XPS, SEM, and TEM spectroscopy were examined to investigate structure, composition, and morphological characteristics. The synthesized nanocomposite exhibited polycrystalline structure with small crystallite size ~ 27 nm in which the particles appeared in sheets like shape with high atomic density on surface. The optical parameters including energy gap (Eg) and refractive index (n) were investigated from (T%) and (R%) measurements through wavelength range from 300-900 nm. Al/Y:ZnO/p-Si/Ag Schottky diode was fabricated using thermal evaporating technique and its current-voltage (I-V) was analyzed using different models. The photodiode showed non-ideal behavior with ideality factor greater than unity and small potential barrier. Under various illuminations, the photodiode has revealed high photosensitivity attributed to trapped charge carriers at the interface. The charge carrier density Nd and built-in voltage Vbi were estimated from Mott Schottky (M-S) function suggesting high Schottky diode efficiency.&amp;#xD;

Design and optimization of a miniaturized dual band rectenna for wireless power transfer applications

This paper presents the design of a compact printed rectenna circuit suitable for wireless power transfer applications at frequencies 900 MHz and 1450 MHz. The rectenna circuit consists of a rectangular patch antenna measuring 17.7 x 8.85 mm2, printed on a Rogers RO4003 substrate. It also includes a voltage doubler (VD) circuit comprising Schottky diodes (SMS7631) and an impedance-matching circuit. The design and optimization of the antenna are performed using Ansys HFSS software, while the DC and RF features of the VD circuit are analyzed using the Advanced Design System (ADS) software. The circuit design is presented in two stages: one for single-frequency operation at 900 MHz and another for dual-band operation at 900 and 1450 MHz. The design of single-stage and double-stage VD for dual-band operation is also discussed in this paper. The rectenna's Power Conversion Efficiency (PCE) is evaluated under various load and input power conditions. The maximum DC output voltage measured is 5.318 V at 900 MHz and 5.52 V at 1450 MHz. Furthermore, the maximum PCE achieved is 53% and 54% for 900 MHz and 1450 MHz respectively. These values are obtained with a RF input power level of 20 dBm and a load resistance of 10 KΩ.

Electrical Properties of Laser Patterned Schottky Diode with ALD-Grown TiO2 Interlayer.

Heterojunction formation is the key to adjusting the electronic and optoelectronic properties of various semiconductor devices. There have been various reports on the formation and importance of semiconducting heterojunction devices based on metal oxides. Titanium dioxide (TiO2) is one of the metal oxides that has many unique properties. TiO2's importance is due to its physical and chemical properties such as large band gap, large permittivity, stability, and low leakage current density. In this context, we present the electrical properties of the metal-insulator-semiconductor (MIS) type-TiO2-based Schottky barrier diode (SBD) in the study. To create a thin layer of TiO2 on p-type silicon (p-type Si) patterned partially by the laser-induced periodic surface structure (LIPSS) technique, an atomic layer deposition (ALD) technique was used in the study. For comparison, the current-voltage (I-V) characteristics of the TiO2-based laser-patterned (LP) and nonlaser-patterned (non-LP) diodes were measured at 300 K and in the dark at ±5 V. Classical thermionic emission (TE) theory and Cheung functions were used to investigate the critical diode parameters of the diodes, including ideality factor (n), series resistance (Rs), and barrier height (Φb). The n values were obtained as 4.10 and 3.68 from the TE method and Cheung functions for the LP diode, respectively. The Φb values were found as 0.68 and 0.69 eV from the TE method and Cheung functions, respectively. According to experimental results, the laser patterning resulted in an increase in the Φb values and a decrease in the n values. After laser patterning, it was observed that the device worked effectively, and the ideality factor and barrier height values were improved. This study provides insight into the fabrication and electrical properties of TiO2-based heterojunction devices.

The effect of FeGa (0/–) level presence on material properties in dilute AlxGa1−xN layers

AlxGa1−xN epilayers are used as the basis of ultraviolet LEDs and detectors. The trap states produced by defects and impurities can play a key role in the device performance. In this work, conventional deep-level transient spectroscopy, photoluminescence (PL), and secondary ion mass spectrometry have been used to characterize a deep-level trap termed as E3 in dilute AlxGa1−xN (x &amp;lt; 0.063) epilayers grown by metal-organic vapor phase epitaxy (MOVPE) on highly conductive ammono-GaN substrates. The AlxGa1−xN epilayers were doped with silicon to about 3 × 1016 cm−3. The electrical and the optical measurements were conducted on Ni/Au Schottky barrier diodes and virgin samples, respectively. First, we observed a general trend that the E3 (FeGa) electron trap concentration significantly changes along the wafers in AlxGa1−xN layers that is fully consistent with previously reported results for GaN materials grown by the MOVPE technique. Second, we report that the activation energies for electron emission for the E1 and E3 traps in dilute AlxGa1−xN exhibit linear variations with Al content. Moreover, low-temperature PL results show a proportional relation between the intensity of the line with its maximum at 1.299 eV and concentration of residual Fe impurity. Finally, we discuss how the presence of defects resulting from Fe contamination may result in degradation of AlxGa1−xN-based devices.

Investigation of hybrid CuPc-doped ZnO/p-silicon photodiodes for photonic and electronic applications

Copper phthalocyanine (CuPc) doped zinc oxide (ZnO) interlayered Al/p-Si Schottky barrier diodes (SBDs) were systematically fabricated utilizing spin coating technique. This study was undertaken to meticulously assess the influence of varying concentrations of CuPc on the intricate electrical and photodiode characteristics of these devices. The investigation involved the characterization of the current–voltage (I–V) characteristics configured with distinct different doping concentrations of CuPc such as 0.05 wt%,1 wt%, 2 wt%, under a wide range of voltages (± 5 V) and illumination irradiances. These measurements enabled the calculation of various critical electrical variables, such as the ideality factor (n), barrier height (ΦB), series resistance (Rs), shunt resistance (Rsh), interface states density (Nss) and their response under various illumination levels (between 10 and 100 mW/cm2) and under dark condition. An increase in the reverse current as the illumination increases suggested the potential utility of these SBDs as photodiodes, photosensors, or photodetectors. Notably, the linear dynamic range (LDR), a crucial factor for image sensors which obtained around 14 for all photodiodes. The photodiodes exhibited a good rectification ratio (RR) of approximately 104. The results obtained indicate that the rectifying properties of the structures can be controlled by CuPc doping. In addition, the results indicated that the presence of CuPc significantly influenced the values of n, ΦB, Rs/Rsh, and Nss. To further analyze the devices, capacitance–voltage (C–V) and conductance–voltage (G–V) measurements were carried out to determine parameters such as diffusion potential (VD), dopant acceptor atoms concentration (NA), Fermi energy level (EF), and width of depletion layer (WD) at both 1 kHz and 1 MHz. The measurements revealed that the capacitance values were higher at low frequencies compared to high frequencies, and this behavior was attributed to Nss. In summary, this study suggests that the manufactured photodiodes have the potential to be employed as photodiodes, sensors, or detectors in optical sensing applications, and their performance can be tailored by adjusting the concentration of CuPc in the ZnO interlayered structures. The discerned outcomes revealed the substantial influence of CuPc concentration on key electrical parameters, with conspicuous trends noted in the values of n, ΦB, Rs/Rsh, and Nss. Furthermore, the observed increase in the reverse current as the illumination level increases highlights the potential utility of these SBDs as sensitive photodiodes/sensors/detectors.

The effect of grain size on diode parameters of Ag/p-NiOx/n-Si/Al based Schottky diode

The effect of grain size on optical properties and designed Ag/p-NiOx/n-Si/Al-based Schottky diode have been investigated. The XRD patterns are used to calculate the grain size of NiOx film, which increases with increasing thickness. Fractal dimensions were estimated from the power spectral density (PSD) algorithm using AFM images. The band gaps were calculated from recorded transmission spectra, showing the reduction of band gap from 3.88 eV to 3.67 eV with increasing grain size. The effect of grain size on the performance of Ag/p-NiOx/n-Si/Al-based Schottky-diodes are analyzed through I-V measurement. The diode parameters of the designed device were calculated using the thermionic emission, Norde, and Cheung models. It is found that the reduction of barrier height of the Schottky diode from 0.95 eV to 0.84 eV with increasing grain size of NiOx films. It is found that the grain size of film strongly impacted on the diode parameters, such as ideality factor (η), potential barrier (φh), series resistance (Rs) performance.

Synaptic behavior in analog memristors based on green-synthesized ZnO nanoparticles

In this work, spherical-like ZnO nanoparticles (NPs) were synthesized via avocado seed extract and calcined at 400 °C, which exhibited a hexagonal wurtzite structure with an average size of around 42 nm. The chemical states, organic residuals, and defects were confirmed by X-ray photoelectron spectroscopy (XPS). The ZnO NPs-based memristors exhibited remarkably stable analog switching, over 300 continuous cycles, and a wide operating window of 400. Moreover, the asymmetry in the current observed was attributed to the self-rectifying nature of this device, comprising one analog memristor and one Schottky diode (1D–1R). By controlling the peak voltage to 4 V and applying 50 bias pulses, it was possible to effectively imitate the key features of synaptic behavior, including potentiation and depression, through current modulation.