Ideality Factor Research Articles

Photoelectrochemical Properties of Chemical Bath Deposited CdNiSe Thin Films

The chemical bath deposition approach was used to prepare Cd1−xNixSe thin film photoelectrodes on a substrate made of stainless-steel plate. The constructed cell has the configuration: p-CdNiSe | NaOH (1M)+S (1M)+Na2S (1M) | C (graphite). Studying current-voltage characteristics in the dark, capacitance–voltage in the dark, barrier-height measurements, power output, photo response, and spectral response are all part of characterizing the photoelectrochemical cell of the photoelectrodes. For the composition of Cd0.7Ni0.3Se, the junction ideality factor was determined to be minimal. It was discovered that the flat band potential and barrierheight was 710 mV and 0.181 eV respectively. The power output characteristic reveals that, for composition x = 0.3, the short circuit current, open circuit voltage, conversion efficiency and fill factor are respectively, 161 μA/cm2, 260 mV, 0.64% and 48.11%. The greatest current recorded at 725 nm is displayed in the spectral response.

Illumination dependent electrical, photosensitivity and photodetectivity properties of Au/SiO2/n-Si structures: optoelectronic situations

Abstract This study aims to examine the electrical, photosensitivity (S), photo-response (R), and photo-detectivity (D*) properties of Au/SiO2/n-type Si structures under different illumination intensities. The illumination-dependent properties of the Au/SiO2/n-type Si structure with SiO2 interlayer were obtained using current–voltage (I-V) characteristics. The ideality factors (n) and barrier heights (Φbo) values of Au/SiO2/n-type Si structures were obtained and compared from forward and reverse bias current–voltage (I-V) measurements at room temperature. Also, barrier heights (Φbo) and series resistance (R S ) values obtained from Norde method were compared with the values obtained from TE theory. It was observed that ideality factor and barrier height values obtained from forward bias region are higher than the values reverse bias. This means that the linearity or rectification feature in the reverse bias region is better than the forward bias region. Furthermore, photodiode values such as photo response (R), photosensitivity (S) and photodetectivity (D*) of Au/SiO2/n type Si structures were also examined depending on the light intensity. Consequently, the experimental results showed that the increase in reverse current with increasing light indicates that the Au/SiO2/n-type Si structures can be used in semiconductor technology as a photodiode, detector or sensor.

Optoelectronic properties of Au/n-type Si semiconductor structures with SiO2 interlayer

In this study, we investigated the effect of light intensity on electrical and photovoltaic properties using current-voltage (I–V) measurements at room temperature of Au/n-type Si structures with SiO2 interface layer. At each light intensity, the obtained main electrical characteristics such as ideality factors (n), barrier heights (Φbo), rectification ratios (RR), saturation currents (I0) and series resistances (RS) of Au/SiO2/n-type Si structures were calculated from both thermionic emission (TE) and Cheung methods using I–V measurements and compared to each other. Experimental results showed that while the n and I0 values increased with the increase in the light intensity, the Φbo and RR values decreased. While the ideality factor values obtained using the TE method ranged between 1.973 (at dark) and 2.250 (for 100 mW/cm2), these values were obtained between 3.227 and 3.482 using the Cheung method. At the same time, while the barrier height values obtained using the TE method ranged between 0.865 eV (at dark) and 0.817 eV (for 100 mW/cm2), these values were obtained between 0.773 eV and 0.742 eV using the Cheung method. It was observed that while the n values obtained from TE theory were smaller than the values obtained from the Cheung method, the Φbo values were larger than the values obtained from the Cheung function. Furthermore, for the Au/SiO2/n-type Si structures, the photovoltaic parameters such as short circuit current (Isc) and open circuit voltage (Voc) and photocurrent (Iph) were examined under dark, daylight and various light intensities (from 20 to 100 mW/cm2).

Effect of 1 wt% Dimethyl Sulfoxide on the Electrical and Photovoltaic Parameters of Schottky Diodes and Organic Solar Cells Based on PEDOT:PSS

Herein, the electrical conductivity of poly(3,4‐ethylenedioxythiophene)–poly(styrenesulfonate) (PEDOT:PSS) polymer is improved by adding dimethyl sulfoxide (DMSO) and electrical characterization of the obtained Schottky diode and organic solar cell (OSC) devices are performed from I–V measurements under the light and dark conditions. The scanning electron microscope images of the poly(3‐hexylthiophene):[6,6]‐phenylC61‐butyric acid methylester active layer and PEDOT:PSS layer are obtained. The series resistance (Rs), barrier height (Фb), and ideality factor (n) parameters are obtained from different techniques as a function of light and dark conditions. Furthermore, photovoltaic parameters are calculated for n‐Si/PEDOT:PSS/Au device without DMSO doping and with DMSO doping as a parameter of the light condition and the interface state densities of these devices are obtained for light and dark conditions. DMSO organic solvent improves the short‐circuit current density (Isc), power convert efficiency (or η), open circuit‐voltage (Voc), shunt resistance (Rsh), and series resistance (Rs) values of OSCs. In summary, DMSO solvent rearranges the conductive of PEDOT:PSS, decreases the work function of this conductive polymer (≈5 eV), decreases energy loss in the charge transportation, and increases photovoltaic parameters of Schottky barrier diode and OSC devices.

Comparative Study on Schottky Contact Behaviors between Ga- and N-Polar GaN with SiNx Interlayer

We conducted a comparative study on the characterization of Ga-polar and N-polar GaN metal–insulator–semiconductor (MIS) Schottky contact with a SiNx gate dielectric. The correlation between the surface morphology and the current–voltage (I–V) characteristics of the Ga- and N-polar GaN Schottky contact with and without SiNx was established. The insertion of SiNx helps in reducing the reverse leakage current for both structures, even though the leakage is still higher for N-polar GaN, consistent with the Schottky barrier height calculated using X-ray photoelectron spectroscopy. To optimize the electric property of the N-polar device, various substrate misorientation angles were adopted. Among the different misorientation angles of the sapphire substrate, the GaN MIS Schottky barrier diode grown on 1° sapphire shows the lowest reverse leakage current, the smoothest surface morphology, and the best crystalline quality compared to N-polar GaN grown on 0.2° and 2° sapphire substrates. Furthermore, the mechanism of the reverse leakage current of the MIS-type N-polar GaN Schottky contact was investigated by temperature-dependent I–V characterization. FP emissions are thought to be the dominant reverse conduction mechanism for the N-polar GaN MIS diode. This work provides a promising approach towards the optimization of N-polar electronic devices with low levels of leakage and a favorable ideality factor.

A biomimetic approach to modulating the sustained release of fibroblast growth factor 2 from fibrin microthread scaffolds

Aim: The pleiotropic effect of fibroblast growth factor 2 (FGF2) on promoting myogenesis, angiogenesis, and innervation makes it an ideal growth factor for treating volumetric muscle loss (VML) injuries. While an initial delivery of FGF2 has demonstrated enhanced regenerative potential, the sustained delivery of FGF2 from scaffolds with robust structural properties as well as biophysical and biochemical signaling cues has yet to be explored for treating VML. The goal of this study is to develop an instructive fibrin microthread scaffold with intrinsic topographic alignment cues as well as regenerative signaling cues and a physiologically relevant, sustained release of FGF2 to direct myogenesis and ultimately enhance functional muscle regeneration. Methods: Heparin was passively adsorbed or carbodiimide-conjugated to microthreads, creating a biomimetic binding strategy, mimicking FGF2 sequestration in the extracellular matrix (ECM). It was also evaluated whether FGF2 incorporated into fibrin microthreads would yield sustained release. It was hypothesized that heparin-conjugated and co-incorporated (co-inc) fibrin microthreads would facilitate sustained release of FGF2 from the scaffold and enhance in vitro myoblast proliferation and outgrowth. Results: Toluidine blue staining and Fourier transform infrared spectroscopy confirmed that carbodiimide-conjugated heparin bound to fibrin microthreads in a dose-dependent manner. Release kinetics revealed that heparin-conjugated fibrin microthreads exhibited sustained release of FGF2 over a period of one week. An in vitro assay demonstrated that FGF2 released from microthreads remained bioactive, stimulating myoblast proliferation over four days. Finally, a cellular outgrowth assay suggests that FGF2 promotes increased outgrowth onto microthreads. Conclusions: It was anticipated that the combined effects of fibrin microthread structural properties, topographic alignment cues, and FGF2 release profiles will facilitate the fabrication of a biomimetic scaffold that enhances the regeneration of functional muscle tissue for the treatment of VML injuries.

Investigation of cryogenic current–voltage anomalies in SiGe HBTs: Role of base–emitter junction inhomogeneities

The deviations of cryogenic collector current–voltage characteristics of SiGe heterojunction bipolar transistors (HBTs) from ideal drift-diffusion theory have been a topic of investigation for many years. Recent work indicates that direct tunneling across the base contributes to the non-ideal current in highly scaled devices. However, cryogenic discrepancies have been observed even in older-generation devices for which direct tunneling is negligible, suggesting that another mechanism may also contribute. Although similar non-ideal current–voltage characteristics have been observed in Schottky junctions and were attributed to a spatially inhomogeneous junction potential, this explanation has not been considered for SiGe HBTs. Here, we experimentally investigate this hypothesis by characterizing the collector current ideality factor and built-in potential of a SiGe HBT vs temperature using a cryogenic probe station. The temperature dependence of the ideality factor and the relation between the built-in potential as measured by capacitance–voltage and current–voltage characteristics are in good qualitative agreement with the predictions of a theory of electrical transport across a spatially inhomogeneous junction. These observations suggest that inhomogeneities in the base–emitter junction potential may contribute to the cryogenic non-idealities. This work helps to identify the physical mechanisms limiting the cryogenic microwave noise performance of SiGe HBTs.

Forward leakage currents in GaN p-i-n diodes

Excessive forward leakage currents in GaN p-i-n diodes were investigated. Traditional diffusion mechanism dominates at VF > 2 V. The effective band gap is derived to be ∼2.21 eV, which is much lower than 3.4 eV and attributed to a band fluctuation caused by dislocations; At 1.35 V < VF < 2 V, a trap-assisted tunneling process becomes important, whose ideality factor is still larger than 4.1 at T = 400 K; Two distinct power-law relationships were observed at lower biases, separated at VF = 0.8 V, whose exponents are extracted to be ∼8 and ∼4, respectively. The behavior is in a good agreement with the space-charge-limited model, featuring an exponentially decaying distribution of trap states below the conduction band.

Research on screening strategy of Organic Rankine Cycle working fluids based on quantum chemistry

The screening of working fluids is one of the key components in the study of power generation systems utilizing low-temperature waste heat. However, the variety of working fluids and their complex composition increase the difficulty of screening working fluids. In this study, a screening strategy for working fluids was developed from the perspective of the thermodynamic physical properties of working fluids. A comparative ideal gas heat capacity via the reduced ideal gas heat capacity factor (RCF) was proposed to characterize the dry and wet properties of working fluids, where RCF &gt; 1 indicated a dry working fluid and RCF &lt; 1 indicated a wet working fluid. A three-step screening strategy was developed for working fluid screening for organic Rankine cycles (ORCs). The strategy comprised basic physical property analysis of working fluids, research on dry and wet properties, and quantum chemical analysis. By comparing the RCF calculation result of 23 selected working fluid with values from the literature, the relative deviations of the data were less than 6.64% overall, indicating that the calculation result of the RCFs is reliable. The selection strategy explains the mechanism of working fluid selection in ORC systems from both micro- and macro-perspectives, laying a foundation for the study of structure-activity relationships in working fluids for ORCs.

Lanthanum(III)hydroxide Nanoparticles and Polyethyleneimine-Functionalized Graphene Quantum Dot Nanocomposites in Photosensitive Silicon Heterojunctions.

Lanthanides are largely used in optoelectronics as dopants to enhance the physical and optical properties of semiconducting devices. In this study, lanthanum(III)hydroxide nanoparticles (La(OH)3NPs) are used as a dopant of polyethylenimine (PEI)-functionalized nitrogen (N)-doped graphene quantum dots (PEI-NGQDs). The La(OH)3NPs-dopedPEI-NGQDs nanocomposites are prepared from La(NO)3 in a single step by a green novel method and are characterized by Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Deposited over an n-type Si wafer, the La(OH)3NPs-dopedPEI-NGQDs nanocomposites form Schottky diodes. The I-V characteristics and the photoresponse of the diodes are investigated as a function of the illumination intensity in the range 0-110 mW cm-2 and at room temperature. It is found that the rectification ratio and ideality factor of the diode decrease, while the Schottky barrier and series resistance increase with the enhancing illuminations. As a photodetector, the La(OH)3NPs-dopedPEI-NGQDs/n-Si heterojunction exhibits an appreciable responsivity of 3.9 × 10-3 AW-1 under 22 mW cm-2 at -0.3 V bias and a maximum detectivity of 8.7 × 108 Jones under 22 mW cm-2 at -0.5 V. This study introduces the green synthesis and presents the structural, electrical, and optoelectronic properties of La(OH)3NPs-dopedPEI-NGQDs, demonstrating that these nanocomposites can be promising for optoelectronic applications.

Methyl-ammonium lead iodide hybrid perovskite thin film as active material for energy conversion devices

The use of hybrid halide Perovskites is helping us get closer to our aim of completely selfsufficient structures in terms of energy production. Preparation of a device of photoactive material CH3NH3PbI3 {FTO (Fluorine-doped tin Oxide)/ CH3NH3PbI3/SpiroOMeTAD/Al} for the photovoltaic applications has been described in this article. Producing a homogeneous thin film through the use of lower temperature, processedsolution devices with one-step spin coating processes is an essential stage in the fabrication process. To generate the thin films on the FTO-substrate, the one-step spin coating approach was utilized for the deposition of the precursor solution, which consisted of methylammonium iodide and lead iodide in a molar ratio of 3:1. This technique was employed to prepare the thin films. The FESEM technique was utilized to carry out the investigation of the surface morphology of this thin layer. In addition, the essential parameters of this device, like barrier height, saturation current, current density, ideality factor, carrier mobility, resistance, carrier lifetime, and capacitance have been computed using current-voltage (I-V) characteristics and the impedance spectroscopy technique. A laser with a power of 20 milliwatts and a wavelength of 532 nanometers was used to light the gadget. The current conduction mechanism exhibits ohmic behavior at a low voltage, while at medium voltages, TFSCLC is the mechanism that regulates charge transportation. Despite the fact that TCSCLC is demonstrated at higher voltages. The TCSCLC model was used to conduct an investigation of the hole's mobility.

Separation of wafer bonding interface from heterogenous mismatched interface achieved high quality bonded Ge-Si heterojunction

In the realm of optoelectronic integration, silicon-based Ge bonding has attracted great attention due to its advantages in short-wave infrared response and low cost. However, owing to the inherent lattice mismatch and thermal mismatch between Ge and Si, the bonded Ge-Si heterogenous interfaces encountered problems of thermal instability and high interface states. Herein, an approach of separating the bonding interface from the heterogenous interface is proposed through inserting a Ge epitaxial layer (GeEL) between the Si substrate and Ge film. This separation modifies the bonding interface to a homogenous one, alleviating the massive mismatch stress and achieving film relaxation, enhancing bonding stability in all aspects. Moreover, during 850 °C annealing, GeEL is doped via diffusion hence realizes electric filed modulation, inhibiting the carrier recombination leakage current and trap assisted tunneling in this defect-rich layer. A Ge-Si heterogenous PIN diode prepared by this bonding method has achieved a remarkable low dark current density (1.33 mA/cm2), a low ideality factor (1.11), and a high on–off ratio (106), confirming the outstanding quality of the bonded heterojunction. This work provides great prospects for higher performance, larger scale and multi-functional Si-based heterogenous material device applications.

High performance of Ag/AlN/Si Schottky diode: Study of the DC sputtering power effect on its electrical properties

The DC sputtering power (DCSP) effect on the chemical composition, structural and electrical properties of Ag/AlN/Si Schottky diode was studied. The AlN films grown on Si substrate were examined by X-ray diffraction (XRD), Fourier Transformed Infra-Red (FTIR), and Raman spectroscopy. The analyzes by XRD, FTIR and Raman show stability at the level of the structure and the qualitative chemical composition of the AlN layer for DCSP of 200 W and 400 W. However, the quantity of chemical compounds on the surface of AlN is affected by this variation. From Current-Voltage (I-V) measurements, the ideality factor (n), barrier height (φb), and series resistance (Rs) were extracted by adopting Cheung functions. Diodes with an AlN interlayer elaborated at 400 W have good rectifying behavior with n, Rs and φb of 3.11, 1930 Ω, and 0.93 eV, respectively. The enhancement of the Ag/AlN/Si diode performance was attributed to the reduction of undesirable impurities in the Ag/AlN interface as well as the morphological improvement of the AlN layer. Capacitance-Voltage (C-V) measurements showed that carrier donor concentrations are strongly affected by DC sputtering power. The elaborate structures may provide new materials with electrical properties having a wide range of applications in electronics and photovoltaic field.

On the temperature dependence of the current conduction mode in non-homogeneous Pt/n-GaN Schottky barrier diode

Forward current-voltage (I–V) measurements of Pt/n-GaN Schottky barrier diode (SBD) are investigated in a wide temperature range (80–400 K). The temperature dependence of the effective Schottky barrier height (SBH) and ideality factor are analyzed on the basis of the thermionic emission (TE) model by considering a double Gaussian distribution (DGD) of SBH due to the presence of barrier height inhomogeneities at the Pt/n-GaN interface. In the high temperature (HT) region (200–400 K), Pt/n-GaN SBD exhibits nearly an ideal behavior in accordance with the TE conduction mode. The obtained values of the homogeneous SBH Φ‾0bn = 1.33 eV and Richardson constant AHT* = 26.86 A cm−2 K−2are in agreement with the theoretical values for n-type GaN. In the low temperature (LT) region (80–160 K), the corresponding values Φ‾0bn = 0.94 eV and ALT* = 14.74 A cm−2 K−2 deduced within the TE mode deviate strongly from the ideal behavior. This deviation is further confirmed by the large ideality factor. In this work, we provide a strong evidence that the tunneling current including thermionic field emission (TFE) largely dominates the conduction mode at low temperature.

Spectroscopic and electronic investigations on tin(II) 2,3-naphthalocyanine/p-Si heterojunction for optoelectronic applications

The spectroscopic and electronic properties of small-molecular organic semiconductors in thin films are a significant aspect that controls the performance of their optical/optoelectronic devices. A heterojunction of thermal vacuum deposited film of tin(II)2,3-naphthalocyanine (SnNc) dye onto a p-type Si wafer (SnNc/p-Si) was fabricated. The morphology of SnNc thin film onto Si wafer was explored using the Field Emission Scanning Electron Microscope (FE-SEM). The specular reflectance and the fluorescent properties of SnNc thin film onto Si wafer were investigated. The PL emission spectra of SnNc/p-Si emission bands are related to the B and Q absorption bands for SnNc. The spectral behavior of the refractive index and the specific polarizability for both SnNc/Glass and SnNc/p-Si were extracted. Under varying temperatures (298–378 K), the electronic properties of the SnNc/p-Si heterojunction were analyzed in dark conditions. The diode parameters of SnNc/p-Si heterojunctions, which exhibited temperature-dependent behavior, were extracted from the current–voltage (I-V) procedure. According to the Cheung-Cheung and Norde procedure, the essential electrical diode parameters of the SnNc/p-Si device, such as the ideality factor, the series resistance, and barrier height, were estimated. The photoconductivity parameters, such as the photocurrent, the sensitivity, and the responsivity of the SnNc/p-Si devices, were estimated. These findings can be helpful and utilized in optoelectronic and organic electronic applications.

A comparison electrical characteristics of the Au/(pure-PVA)/n-Si and Au/(CdTe doped-PVA)/n-Si (MPS) type Schottky structures using I–V and C–V measurements

In this study, both the Au/(pure-PVA)/n-Si (MPS-1) and Au/(CdTe:PVA)/n-Si (MPS-2) type Schottky diodes (SDs) were fabricated onto the same n-Si wafer in same conditions. After that, their electrical parameters were obtained from the current–voltage (I–V) and capacitance–voltage (C–V) measurements and compared to each other to determine the effect (CdTe:PVA) interlayer on the performance of MPS type SD. The saturation current (Is), ideality factor (n), rectification ratio (RR = Ifor./Irev.), zero-bias barrier height (ΦBo), and series/shunt resistances (Rs, Rsh) were derived utilizing I–V data. The values of Io, n, and ΦBo were found as 9.13 × 10–7 A, 11.07, 0.63 eV for MPS1 and 1.54 × 10–10 A, 3.97, 0.85 eV for MPS2, respectively. The C−2–V graphs were drawn for 0.7 MHz to obtain the doping concentration of donor atoms (ND), Fermi energy (EF), BH/(ΦB(C–V)), depletion layer width (WD), and maximum electric field (Em). The Nss − (Ec − Ess) profile for two SDs was produced from the I–V data by considering the voltage dependence of n and BH. The values of surface states (Nss) were changed between 4.8 × 1013 and 1.7 × 1014 eV−1 cm−2 for MPS1 and 5 × 1012 and 1.15 × 1013 eV−1 cm−2 for MPS2, respectively. All experimental results show that the (CdTe:PVA) interlayer significantly improved the quality of the MS type SDs rather than (pure-PVA) in terms of lower values of leakage/saturation current, n, Nss, and higher RR, BH, and Rsh when compared (pure-PVA) interlayer. The (CdTe:PVA) interlayer may be used instead of the conventional interlayer in the future.

Improvement of Ga2O3 vertical Schottky barrier diode by constructing NiO/Ga2O3 heterojunction

The high critical electric field strength of Ga2O3 enables higher operating voltages and reduced switching losses in power electronic devices. Suitable Schottky metals and epitaxial films are essential for further enhancing device performance. In this work, the fabrication of vertical Ga2O3 barrier diodes with three different barrier metals was carried out on an n–-Ga2O3 homogeneous epitaxial film deposited on an n+-β-Ga2O3 substrate by metal−organic chemical vapor deposition, excluding the use of edge terminals. The ideal factor, barrier height, specific on-resistance, and breakdown voltage characteristics of all devices were investigated at room temperature. In addition, the vertical Ga2O3 barrier diodes achieve a higher breakdown voltage and exhibit a reverse leakage as low as 4.82 ×10−8 A/cm2 by constructing a NiO/Ga2O3 heterojunction. Therefore, Ga2O3 power detailed investigations into Schottky barrier metal and NiO/Ga2O3 heterojunction of Ga2O3 homogeneous epitaxial films are of great research potential in high-efficiency, high-power, and high-reliability applications.

Electrical characterization of Ag/MoO3−x/p-Si Schottky diodes based on MoO3−x synthesized via sol–gel method: an investigation on frequency and voltage dependence

MoO3−x is a commonly used buffer layer in organic based optoelectronic devices to align energy level between active semiconductor and metal layer. The purpose of this study is to show the effects of the MoO3−x interlayer by comparing with a reference device without MoO3−x interlayer. To evaluate the effect of MoO3−x interlayer synthesized by sol–gel method, basic important parameters such as ideality factor (n), barrier height (∅\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\varnothing$$\\end{document}B), interface states (Nss) and series resistance (Rs) of Ag/MoO3−x/p-Si and Ag/p-Si Schottky diodes were calculated by electrical characterization methods. The current–voltage (I–V) measurements show that the ideality factor for the p-Si/Ag reference diode was decreased from 2.4 to 1.9 while rectification factor increasing 44.6 times using MoO3−x interlayer, and frequency–dependent measurements (C–V–f, G–V–f) were carried out to elucidate this deviation at room temperature for MoO3−x-based diode. From the XPS analysis, it was seen that Mo+6 and Mo+5 oxidation states were intense on the surface of the MoO3−x film, and the Mo+4 oxidation state increased as it went into the bulk. The changes in Rs and Nss due to the energy levels formed by the Mo+6 and Mo+5 oxidation steps at the interface are depicted. In addition, the energy density distribution profile of Nss was obtained using the I–V characteristics for various forward bias voltages range from 2.1 × 1012 to 2.5 × 1012 eV−1 cm−2. Based on the experimental results, the sol–gel synthesized MoO3−x thin film exhibits favorable rectification characteristics and holds promise for application as a Schottky diode.

Three-step field-plated β-Ga2O3 Schottky barrier diodes and heterojunction diodes with sub-1 V turn-on and kilovolt-class breakdown

A unique field termination structure combining a three-step field plate with nitrogen ion implantation to enhance the reverse breakdown performance of Pt/β-Ga2O3 Schottky barrier diodes (SBDs) and NiO/β-Ga2O3 heterojunction diodes (HJDs) is reported. The fabricated devices showed a low R on,sp of 6.2 mΩ cm2 for SBDs and 6.8 mΩ cm2 for HJDs. HJDs showed a 0.8 V turn-on voltage along with an ideality factor of 1.1 leading to a low effective on-resistance of 18 mΩ cm2. The devices also showed low reverse leakage current (<1 mA cm−2) and a breakdown voltage of ∼1.4 kV. These results offer an alternative, simpler route for fabricating high-performance kilovolt-class β-Ga2O3 diodes.

Electrical and Optical Properties of a Cu2O/β‐Ga2O3 pn‐Junction

A pn‐heterojunction is fabricated by depositing an n‐type β‐Ga2O3 film by pulsed laser deposition (PLD) on c‐cut Al2O3. P‐type cuprous oxide films, Cu2O, are then deposited by PLD, as well as by radio frequency (RF) magnetron sputtering. It is concluded that hole injection is prohibited by a 3.26 eV valence band barrier, as measured by X‐ray photo‐electron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). Heterojunction diode structures are prepared on the front side and electrical measurements demonstrate a rectification ration of 8 orders of magnitude and an ideality factor close to 2, indicating interface recombination‐controlled forward current. The junction is also optically active and shows a very fast photo‐response to 275 nm UV light.