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Gallium Oxide (Ga2O3) devices have shown great potential for radiation detection. However, developing Ga2O3 detectors for pulsed radiation monitoring is still challenging, which requires high response sensitivity (R), low noise, high time resolution, and linear outputs. Herein, a vertical p‐NiO/β‐Ga2O3 heterojunction diode (HJD) is fabricated and its performance in X‐ray detection is analyzed. Benefiting from the high quality of the p‐n heterojunction, the HJD exhibits a low‐leakage current density of less than 1.73 × 10−7 A cm−2 at 100 V and features a high R of 7.92 μC Gy−1 cm−2, a low noise equivalent dose rate of 9.14 × 10−12 Gy−1 Hz−0.5 at an X‐ray dose rate of 0.383 Gy s−1, and good linear outputs to X‐ray dose rates from 0.0383 to 1.149 Gy s−1. The conductive process of the HJD detector is dominated by the tunneling mechanism, which leads to a longer response time associated with the trapping and releasing process of the deep‐level traps under the continuous X‐ray illumination. However, the pulsed X‐ray response property shows no significant influence from the slow trapping/releasing process of the traps. As a result, pulsed X‐ray radiation detection with a 50 ns full width is achieved, and the time resolution of the detector is characterized to be 3.31 ns by a 20 ps laser source. [ABSTRACT FROM AUTHOR]

The current work presents a new structure based on Au/PVA/SiO2/p-Si/Al that has not been studied before. An aqueous solution of polyvinyl alcohol (PVA) polymer gel was deposited on the surface of SiO2/Si using the spin-coating technique. The silicon wafer was left to be oxidized in a furnace at 1170 k for thirty minutes, creating an interdiffusion layer of SiO2. The variations in the dielectric constant (Є′), dielectric loss (Є″), and dielectric tangent (tanδ) with the change in the frequency, voltage, and temperature were analyzed. The results showed an increase in the dielectric constant (Є′) and a decrease in the dielectric loss (Є″) and tangent (tanδ); thus, the Au/PVA/SiO2/p-Si/Al heterostructure has opened up new frontiers for the semiconductor industry, especially for capacitor manufacturing. The Cole–Cole diagrams of the Є″ and Є′ have been investigated at different temperatures and voltages. The ideality factor (n), barrier height (Φb), series resistance (Rs), shunt resistance (Rsh), and rectification ratio (RR) were also measured at different temperatures. [ABSTRACT FROM AUTHOR]

We fabricated a heterojunction structure composed of n-CdS and p-C10H10N2 films. The CdS film was prepared using the CBD method, while the C10H10N2 film was prepared using the spin coating method. Later, we performed the current-voltage (I-V) measurement of this PN diode which we made using Keithley 2400 sourcemeter. As can be seen from the logI-V diagram, this heterojunction structure exhibits rectifying properties. Using traditional methods, an ideality factor (n) of 1.93 and a barrier height value (Φb) of 0.79 eV were determined. An ideality factor of more than one indicates non-ideal I-V behavior in the CdS/C10H10N2 heterojunction diode formed. The interface layer, interface states and series resistance are some of the causes of this deviation. Moreover, Cheung's functions and a modified Norde function were used to determine the diode parameters, such as ideality factor, barrier height, and series resistance. With the Cheung method, n=4.33, series resistance (RS)=168.65 kΩ and Φb=0.62 eV were found. Additionally, RS=686.08 kΩ and Φb=0.78 eV were found by the Norde method. Consistent barrier height values were found in all methods through comparison, suggesting compatibility. However, it was discovered that the series resistance values yielded by the Norde function exceeded those obtained by the Cheung functions. [ABSTRACT FROM AUTHOR]

The advent of two-dimensional (2D) materials has led to innovative and compact electronic devices with remarkable properties. In this work, we introduce a switchable bidirectional diode (2D BDiode), fabricated entirely using different 2D materials, that serves as a fundamental building block for various analog circuit applications. This proof-of-concept diode exhibits the ability to control the flow of current in both forward and reverse bias configurations, enabling advanced functionality in the realm of analog circuit design. We provide a SPICE-based model for the diode based on current-voltage device characterization, capturing its behavior under different biasing conditions, and finally demonstrate a few potential use cases of the 2D BDiode including AC/DC conversion, DC/AC conversion and charge pump circuits.

The current work presents a new structure based on Au/PVA/SiO2/p-Si/Al that has not been studied before. An aqueous solution of polyvinyl alcohol (PVA) polymer gel was deposited on the surface of SiO2/Si using the spin-coating technique. The silicon wafer was left to be oxidized in a furnace at 1170 k for thirty minutes, creating an interdiffusion layer of SiO2. The variations in the dielectric constant (Є′), dielectric loss (Є″), and dielectric tangent (tanδ) with the change in the frequency, voltage, and temperature were analyzed. The results showed an increase in the dielectric constant (Є′) and a decrease in the dielectric loss (Є″) and tangent (tanδ); thus, the Au/PVA/SiO2/p-Si/Al heterostructure has opened up new frontiers for the semiconductor industry, especially for capacitor manufacturing. The Cole–Cole diagrams of the Є″ and Є′ have been investigated at different temperatures and voltages. The ideality factor (n), barrier height (Φb), series resistance (Rs), shunt resistance (Rsh), and rectification ratio (RR) were also measured at different temperatures.

In this study, the performance of dye-sensitized photovoltaic cells and electron charge recombination properties of p-n heterojunction diodes were enhanced by incorporating TiO2 into pristine ZnO nanoparticles. The ZnO nanomaterials were prepared using a green mediated technique, and the TiO2 deposition over ZnO nanoparticles was achieved through the sol–gel method. Structural analysis confirmed that the ZnO nanoparticles exhibited a hexagonal wurtzite structure, while the TiO2 nanoparticles displayed a hexagonal structure. Morphological analysis revealed that the ZnO particles had a spherical shape, whereas TiO2 particles formed clusters. The nanomaterials were further investigated to assess their functional, linear optical, and magnetic properties. For the p-n heterojunction analysis, n-type pure ZnO and ZnO/TiO2 nanomaterials were coated onto a p-type silicon substrate. The results demonstrated that the incorporation of TiO2 nanomaterials improved the coercivity and magnetization of the device. Moreover, the power conversion efficiency of the dye-sensitized solar cells significantly increased for the ZnO/TiO2 photoanode, indicating a reduced charge recombination. The TiO2 incorporated ZnO exhibited a higher efficiency (7.85%) compared to pristine ZnO (7.47%). [ABSTRACT FROM AUTHOR]

Thin films of nanocrystalline selenium (Se) of different thicknesses were grown on annealing from 323 to 398 K. The crystallinity of the layers increased with annealing temperatures (TA). The temperature thickness correlations were established. The layers exhibited spherical-shaped particles at higher annealing temperatures. The grown layers possess hexagonal crystal system with space group P3121(152); it shows prominent planes along the a-axis. The bandgap (Eg) decreases from 2.18 to 1.94 eV, 2.12 to 1.82 eV, and 2.13 to 1.84 eV with changes in TA of 700, 270, and 150 nm thick layers, respectively. The high absorption coefficient (α) values ∼ 1 × 105 cm−1 observed in all films makes it suitable as an absorber layer in a solar cell structure and an optical sensor. The FTO/p-Se/n-CdS/In heterojunction diodes provide zero-bias barrier height (фbo) of 0.788(7) eV. The open circuit voltage (Voc) of FTO/p-Se (150 nm)/n-CdS(200 nm)/In a photovoltaic cell was observed to be 55 mV.

In this work we present studies on the influence of oxygen partial pressure on the properties of sputtered vertical NiO/β-Ga 2 O 3 heterojunction diodes. Obtained results shows substantial effect of oxygen partial pressure on the electrical properties of NiO/β-Ga 2 O 3 heterojunction diodes. The diodes with NiO layers deposited in pure Ar shows Schottky-like I-V characteristics with low ideality factor of 1.05 and barrier height of 1.27 eV as well as low turn-on voltage close to 1V. On the other hand, diodes with NiO layer deposited in oxygen containing atmosphere shows typical p-n diode characteristics. The best electrical characteristics i.e. low on-state resistance of 2.85 mΩcm2, lack of defects and low ideality factor down to 1.07 at RT along with high breakdown voltage close to 900V without any junction termination, were obtained for diodes with NiO layers deposited at 50 % oxygen content. We have demonstrated that by optimization of oxygen partial pressure, the properties of NiO/β-Ga 2 O 3 heterojunction diodes can be tuned and excellent electrical performance in terms of low-on state resistance, high breakdown voltage, low-leakage current and low ideality factor, can be obtained. [ABSTRACT FROM AUTHOR]

A 4H-SiC MOSFET with p-type region injection and integrated split gate and heterojunction diode is proposed in this paper. Compared with the conventional MOSFET, the proposed structure has a lower on-resistance and switching loss. And the gate oxide layer has been well protected by the p-type region, which reduces the electric field in gate oxide layer at the off-state. The on-resistance of device can be greatly reduced by increasing the doping concentration of current spreading layer and will not cause a huge electric field in gate oxide layer. The specific on-resistance is decreased by about 27.8% and the static characteristic (BV2/ $\text{R}_{\mathrm{ on,sp}}$ ) of the device is improved about 37.3%. SiC material has a high third quadrant turn-on voltage due to its wide band gap characteristics. The use of heterojunction integration can take place of parasitic body diode and reduce its turn-on voltage, avoid the bipolar degradation effect, and improves the reverse recovery characteristics. To evaluate the dynamic performance, the reverse transmission capacitance ( $\text{C}_{\mathrm{ rss}}$ ) and gate-drain charge ( $\text{Q}_{\mathrm{ gd}}$ ) of the proposed structure have been studied in this paper via numerical simulations. Based on the simulation, the HF-FOM ( $\text{C}_{\mathrm{ rss}} {\times }\text{R}_{\mathrm{ on,sp}}$ ) and HF-FOM2 ( $\text{Q}_{\mathrm{ gd}} {\times }\text{R}_{\mathrm{ on,sp}}$ ) of the proposed structure are decreased by about 87% and 86%, respectively. Meanwhile, the reverse turn-on voltage and reverse recovery characteristics are also improved, and the total energy loss decreases by about 37.3%.

In this paper, a 650 V 4H-SiC trench Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) with a hetero-junction diode (HJD) and double current spreading layers (CSLs) is proposed and studied based on Sentaurus TCAD simulation. The HJD suppresses the turn-on of the parasitic body diode and improves the performance in the third quadrant. CSLs with different doping concentrations help to lower the on-state resistance as well as the gate-drain capacitance. As a result, the on-state resistance is decreased by 47.82% while the breakdown voltage remains the same and the turn-on and turn-off losses of the proposed structure are reduced by 83.39% and 68.18% respectively, compared to the conventional structure. [ABSTRACT FROM AUTHOR]

The paper presents structural and dielectric properties of Polypyrrole-MWCNTs/TiO2/Al2O3/n-Si emphasizing that one of the superior characteristics is the appearance of negative dielectric constant and dielectric loss tangent at both high and low frequencies. It may worth mentioning that the need to develop electronic devices based on new materials combination has motivated the development of such structures as supercapacitors and diodes. The structural characterization of PPy-MWCNTs/TiO2/Al2O3/n-Si was investigated using X-ray diffraction, FTIR, Raman spectroscopy, and scanning electron microscope. The oxide film thickness (dox), the density of state (NSS), admittance (Ym), electric field (Em), depletion layer width (Wd), and ΔΦb (eV) were examined using the C−2 − V relationship. At low frequencies, the values of Wd, Φb increase, however as frequency rises, the Wd, Nss, and Rs decrease. The dielectric constant (ɛ`) takes only negative values at a high frequency of 2x107 Hz, whereas it takes both negative and positive values at frequencies of 107, 100, and 10 Hz. The dielectric loss tangent (tanδ) has positive and negative values at frequencies 107, 106, 100, and 10 Hz.

Vertical p-n hetero-junction diodes (HJDs) were fabricated by employing NiO x / β -Ga 2 O 3 with p-NiO x junction termination extension (JTE). It is found that NiO x JTE leads to reduce interface states density in devices based on a smaller voltage hysteresis interval in I-V hysteresis analysis and a decrease in parasitic capacitance in C-V characteristics. It is due to the fact that JTE help to the retrain the activation of interface states. This study provides a basic understanding of interface states and lays the groundwork for the development of guiding principles for the design of Ga 2 O 3 HJDs. [ABSTRACT FROM AUTHOR]

In this paper, we propose 4H-SiC UMOSFET structure with improved single-event burnout (SEB) hardening characteristics, and compare it with the conventional UMOSFET structure by conducting numerical technology computer-aided design (TCAD) simulations. The SEB safe operating areas are extracted when heavy ions with different linear energy transfer (LET) collide with the device. Because integrated heterojunction diode (HJD) in proposed structure features hole collection effect due to the difference of the valence band energy level, the generated hole current can be leaked off efficiently. With a LET value of $0.01~{\sim }~0.09$ pC/ ${\mu }\text{m}$ , the proposed MOSFET has 25% higher SEB threshold voltage than conventional MOSFET due to the suppressed parasitic BJT operation. Therefore, proposed structure can provide superior SEB viability for space and atmospheric applications. [ABSTRACT FROM AUTHOR]

The paper presents structural and dielectric properties of Polypyrrole-MWCNTs/TiO2/Al2O3/n-Si emphasizing that one of the superior characteristics is the appearance of negative dielectric constant and dielectric loss tangent at both high and low frequencies. It may worth mentioning that the need to develop electronic devices based on new materials combination has motivated the development of such structures as supercapacitors and diodes. The structural characterization of PPy-MWCNTs/TiO2/Al2O3/n-Si was investigated using X-ray diffraction, FTIR, Raman spectroscopy, and scanning electron microscope. The oxide film thickness (dox), the density of state (NSS), admittance (Ym), electric field (Em), depletion layer width (Wd), and ΔΦb (eV) were examined using the C−2 − V relationship. At low frequencies, the values of Wd, Φb increase, however as frequency rises, the Wd, Nss, and Rs decrease. The dielectric constant (ɛ') takes only negative values at a high frequency of 2x107 Hz, whereas it takes both negative and positive values at frequencies of 107, 100, and 10 Hz. The dielectric loss tangent (tanδ) has positive and negative values at frequencies 107, 106, 100, and 10 Hz. [ABSTRACT FROM AUTHOR]

In this paper, a 650 V 4H-SiC trench Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) with a hetero-junction diode (HJD) and double current spreading layers (CSLs) is proposed and studied based on Sentaurus TCAD simulation. The HJD suppresses the turn-on of the parasitic body diode and improves the performance in the third quadrant. CSLs with different doping concentrations help to lower the on-state resistance as well as the gate-drain capacitance. As a result, the on-state resistance is decreased by 47.82% while the breakdown voltage remains the same and the turn-on and turn-off losses of the proposed structure are reduced by 83.39% and 68.18% respectively, compared to the conventional structure.

A split-gate SiC trench MOSFET with a hetero-junction diode (HJD) is proposed and numerically analyzed in this paper. The proposed structure features the HJD to effectively suppress the turn-on of the parasitic body diode and reduce the depletion region in the JFET area. A P+ shielding layer surrounding the HJD and the gate oxide layer is used to alleviate the concentration of the electric field under the gate trench and improve the switching performance. As a result, not only the breakdown voltage is increased by 20.8% at the same level of the on-state resistance but also the miller charge and the switching loss of the proposed structure are reduced by 52% and 39.1%, respectively when compared with those of the conventional SiC trench MOSFET.

This study proposes a different technique known as the thermionic vacuum arc to produce a TiO2/Si heterojunction photodiode with better electrical properties than literature like the ideality factor indicating that the method is very suitable to form an outstanding quality heterojunction interface. The heterojunction is highly sensitive to different light intensities and has stable photocurrent characteristics as a photodiode. Structural and morphological properties of the produced TiO2/Si heterostructure surfaces were investigated via XRD and AFM, respectively. According to XRD analysis, it was observed that the TiO2 thin film was in a polycrystalline structure with the Anatase and Brookite phases. Also, the film surface is homogenous, and a low roughness value was measured as 3 nm. The thin film thickness and the bandgap values (Eg) were determined based on optical methods. The electrical parameters of TiO2 thin film, such as conductivity type, charge carrier density, and mobility, were also determined by Hall Effect Measurement. The Ag/TiO2/Si/Ag heterojunction device characteristics were determined by conducting the current-voltage (I-V) measurement. The ideality factor (n) and the barrier height (Φb) values were determined as 1.7 and 0.65 eV, respectively. The photo-response performance was measured via transient photocurrent (I-T) measurements for different light intensities. [ABSTRACT FROM AUTHOR]

The p-n junction is the fundamental form of an electronic semiconductor device. A p-CuO/n-ZnO heterojunction diode was formed by using thermal evaporation and thermal oxidation techniques. Cupric oxide (CuO) films of 300 µm in thickness were obtained by thermal oxidation of Cu foils. Zinc oxide (ZnO) films of 30 µm in thickness were prepared in two process steps: firstly, thermal evaporation of Zn at atmospheric pressure, and then thermal oxidation to Zn films. The p-CuO/n-ZnO heterojunction diode was formed by performing the steps of ZnO deposition on the surface of the CuO films, and completed by deposition of silver electrical contacts on the top and on the bottom sides of the heterostructure. Structural, morphological, and electrical properties of CuO and ZnO were studied by X-ray diffraction (XRD), Raman spectroscopy, Uv–Vis DRS, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Hall effect techniques. Current-voltage (I-V) measurements were performed to the p-CuO/n-ZnO heterojunction diode. Structural characterization to CuO confirmed that pure, crystalline and (111) textured films can be obtained by thermal oxidation of Cu. ZnO films showed a polycrystalline structure without preferred orientation. The band gap of CuO and ZnO were 1.51 and 3.21 eV, respectively. Cross-sectional SEM and TEM images confirmed the formation of the p-CuO/n-ZnO heterojunction diode. Hall measurements confirmed the p-type conductivity of CuO and the n-type conductivity of ZnO. Also, the carrier concentration and Hall mobility of CuO films were 9.54 × 1012 cm−3 and 267 cm2 V−1 s−1, respectively. ZnO films exhibited a carrier concentration and Hall mobility of 3.69 × 1012 cm−3 and 22.18 cm2 V−1 s−1, respectively. The I-V measurement showed that the p-CuO/n-ZnO heterojunction exhibits a low turn-on voltage of about 0.8 V and a breakdown voltage of about 38 V. Electrical parameter such as rectification ratio and ideality factor were also calculated. An energy band-diagram of the CuO/ZnO heterojunction was proposed, where a built-in voltage of 0.57 eV was observed.

Room temperature electronic nose sensor arrays are of interest to numerous sensing applications as they can detect multiple gases selectively. One prerequisite in a sensor array is the absence of the heating element, which can considerably reduce design complexity and power consumption while providing multiple gas detection on one substrate. In this work, we show the fabrication of an electronic nose that implements an array of two Schottky diode and two heterojunction diode hydrogen sensors using Ta2O5 and WO3 on the same substrate. The gas sensitive layers were fabricated via RF sputtering and 500°C post-annealing. We demonstrate room temperature sensitivity with fast hydrogen and hydrocarbon gas detection in the order of seconds under different biases. The device exhibits unique response when exposed to H2, CH4, C2H6 and C3H8 gases sequentially. The effects of humidity on each sensor were also examined. [ABSTRACT FROM AUTHOR]

A novel PIN-junction gate 4H-SiC UMOSFET with integrated heterojunction (PJG-UMOSFET) is proposed and numerically studied. The integrated heterojunction diode effectively suppresses the conduction of the intrinsic PN diode in the reverse conduction state of PJG-UMOSFET. The device simulation results show that the on-resistance (R on) of the device is reduced by about 20.5 % compared with the traditional SiC UMOSFET, and there is almost no specific conduction resistance decrease. The reverse recovery time (t π) and reverse recovery charge (Q π) are reduced by 42.1 % and 68.4 %, and the gate-to-drain charge is reduced by 41.2 %. In addition, a feasible manufacturing process method for the proposed device is provided. • The reverse recovery performance of the proposed SiC MOSFET is significantly improved. • The gate charge performance of the proposed SiC MOSFET is significantly improved. • The reverse I-V performance of the proposed SiC MOSFET is significantly improved. • The improvement is mainly due to the PIN-junction gate and the heterojunction. [ABSTRACT FROM AUTHOR]

A 1.2 kV SiC MOSFET with an integrated heterojunction diode and p-shield region (IHP-MOSFET) was proposed and compared to a conventional SiC MOSFET (C-MOSFET) using numerical TCAD simulation. Due to the heterojunction diode (HJD) located at the mesa region, the reverse recovery time and reverse recovery charge of the IHP-MOSFET decreased by 62.5% and 85.7%, respectively. In addition, a high breakdown voltage (BV) and low maximum oxide electric field (EMOX) could be achieved in the IHP-MOSFET by introducing a p-shield region (PSR) that effectively disperses the electric field in the off-state. The proposed device also exhibited 3.9 times lower gate-to-drain capacitance (CGD) than the C-MOSFET due to the split-gate structure and grounded PSR. As a result, the IHP-MOSFET had electrically excellent static and dynamic characteristics, and the Baliga’s figure of merit (BFOM) and high frequency figure of merit (HFFOM) were increased by 37.1% and 72.3%, respectively. Finally, the switching energy loss was decreased by 59.5% compared to the C-MOSFET.

To investigate the effects of Mn dopant on n-ZnO/p-Si device performance, ZnO films were produced in different Mn dopant by the sol gel spin coating method. Morphological properties of the films were studied by FESEM. Then, the n-ZnO:Mn/p-Si heterojunction diodes were fabricated. The diode parameters were determined by I-V measurements. The n values of the diodes were found to be 8.38, 6.84 and 3.87, respectively, for the diodes produced using undoped, 1% Mn doped and 3% Mn doped ZnO films. At the same time, electrical parameters were determined to compare by using Cheung and Norde methods. According to the evaluation of n values obtained by different methods, an improvement on the rectifying properties of the ZnO diode with Mn dopant has been observed. In the continuation of the study, the photovoltaic properties of the heterojunction diodes have been studied. The results obtained at different illumination intensities showed that the diodes are sensitive to light. C-V measurements of the fabricated diodes are also investigated in detail. [ABSTRACT FROM AUTHOR]

In the present study, we investigated the effect of Mg doping level (0, 1, 3, 5, 7, 10, 20 and 30% Mg) and annealing temperature (T A : 773, 823, 873 and 973 K) on the structural optical and electric properties of highly c-axis oriented Mg-doped ZnO (ZMO) thin films deposited on p-Si by sol-gel spin-coating process. The ZMO thin films were analyzed by x-ray diffraction, field emission scanning electron microscopy (FESEM), x-ray photoelectron spectroscopy (XPS), Fourier-transform infrared, ultraviolet/visible (UV/VIS) spectrophotometer. The highly c-axis oriented ZnO hexagonal structure was observed in all thin films. Crystallite size increased at higher annealing temperature (T A), whereas decreased with increasing certain Mg doping ratios except for the 5 and 7%. The FESEM analyses showed that more homogeneous distribution of nanospherical particles, increased in size at higher T A treatments, whereas their size decreased with increasing Mg doping concentrations except for the 5 and 7%. Energy dispersive spectra and XPS analyses confirmed the insertion of Mg2+ within ZnO lattice. Optical band gap value was increased by Mg doping ratio, whereas decreased at higher T A. The ZMO thin films showed a relatively high transmittance, Extinction coefficient decreased with increasing Mg doping ratio, however, increased at higher T A treatments. Refractive index was also decreased at higher Mg doping levels except for the 20% doping level. Depending on the applied voltage and Mg doping level the rectifying behaviour with high rectification ratio was observed from current-voltage (I-V) characteristics of ZMO/p-Si heterojunction diodes. Overall, our study clearly showed that the 20% Mg-doped ZnO thin films had the optimum optical and I-V characterizations. • Highly c-axis oriented Mg-doped ZnO (ZMO) thin films derived by solution process. • Improved crystallization, Zn-Mg-O bonding, optical quality by annealing tempreture (T A) • I-V characterization of ZMO/p-Si junction showed strong dependence on T A. • Overall, the highest optical quality in 20% Mg-doped ZnO thin films. • *Overall, the most ideal diode obtained in ZMO/p-Si junction with 20% Mg doping level. [ABSTRACT FROM AUTHOR]

Abstract This paper analyzes the electrical parameters of Si/ZnO heterojunction diodes in the wide temperature range, i.e. from room temperature (298 K) to 573 K to study the electrical performance of the diode in very high temperature environment. In this work, sol-gel derived nanostructured ZnO thin film was deposited directly on p-Si substrate using spin coating technique. Electrical parameters, such as rectification ratio, reverse saturation current, ideality factor, barrier height, series resistance and activation energy are derived from current-voltage characteristics of the device, measured using semiconductor parameter analyzer in the temperature range of 298 K–573 K for bias voltage of ±5 V. The ideality factor, barrier height and series resistance is derived as 2.66, 0.789 eV and 3554 Ω respectively at 298 K, whereas at 573 K these are modified as 1.58, 1.15 eV and 801 Ω respectively. The above-mentioned results indicate the presence of spatial barrier height inhomogeneities (BHI) in high temperature environment. Hence, we have included the Gaussian distribution of spatial BHI in our analysis to calculate the effective Richardson constant (RC). Before inclusion of spatial BHI, RC was 4.026 × 10−6 Acm−2K−2. However, after inclusion of spatial BHI, RC is modified to 29.14 Acm−2K−2, which is nearer to the theoretical value (32 Acm−2K−2). Therefore, this study indicates that our as-fabricated Si/ZnO heterojunction diodes can sustain their electrical behaviour in very high temperature environment also and they are suitable for high temperature electronic and optoelectronic application. Highlights • Synthesize ZnO thin film on p-Si substrate using Sol-gel Spin coating method. • Electrical parameters of Si/ZnO heterojunction diode are derived experimentally. • Results are analyzed using trap-assisted tunneling and barrier height inhomogeneities. • Gaussian distribution of BH inhomogeneities is considered to modify Richardson plot. • Modified R constant is 29.14 Acm−2K−2, i.e. nearer to theoretical value 32 Acm−2K−2. [ABSTRACT FROM AUTHOR]

Abstract The fabrication of p-n heterojunction diodes using semiconducting metal-oxides obtained from a solution-based method was investigated. Initially, n-type transparent cadmium stannate (Cd 2 SnO 4) conducting films were deposited by the dip-coating method on glass substrates. The films were sintered in air for 1 h at 550 °C and annealed in vacuum for 10 min at 550 °C. A low resistivity value was obtained (ρ ≈ 2 × 10−3 Ω-cm) for films with average thickness of ∼ 380 nm. For the p-type layer, cupric oxide (CuO) was deposited using the dip-coating method over the transparent conductive oxide. Several layers were deposited and a drying process in air was applied at 250 °C for each coating. CuO thickness (τ) was in the 49–270 nm range as the number of coats varied from 5 to 14. After that, the samples were subjected to a rapid thermal annealing treatment (RTA) in vacuum during 10 min at a temperature T A , within the 300 °C ≤ T A ≤ 450 °C range, depending on τ, to reduce the CuO phase into the cuprous oxide (Cu 2 O) phase. Cu 2 O has shown a better crystalline quality and lower resistivity than CuO, obtaining a more efficient charge transport. From the X-ray diffraction patterns obtained from the heterojunction, the presence of Cd 2 SnO 4 is confirmed. The CuO layer after RTA treatment shows three different types of films, depending on both T A and τ: i) CuO (amorphous)+Cu 2 O, ii) Cu 2 O and iii) Cu 2 O + Cu. Specular reflectance measurements were performed to show the presence of amorphous CuO and to confirm the full transformation from CuO to Cu 2 O. Current-voltage measurements were performed using silver paste on Cd 2 SnO 4 and a graphite probe on the copper oxide layer, as ohmic contacts. All heterojunctions with a copper oxide layer of ∼ 49 nm, show an ohmic behavior. For higher τ, independent of the type of copper oxide film, a rectifying behavior is shown, which improves as τ increases and only the Cu 2 O phase is obtained. Best rectification is achieved in samples with ∼ 270 nm of Cu 2 O at T A = 425 °C. In this work, as far as we know, for first time Cu 2 O/Cd 2 SnO 4 diodes were fabricated using the dip-coating method. The electrical parameters for the best rectification were: ideality factor (n = 4.8), saturation current density (J 0 = 3.20 × 10−5 A/cm2) and turn-on voltage (V to = 1.1 V). Highlights • Cu 2 O/Cd 2 SnO 4 heterojunction obtained by dip-coating method and using RTA treatments. • J 0 , n , R S and R SH electrical parameters of Cu 2 O/Cd 2 SnO 4 diodes were determined. • Recombination in Cu 2 O/Cd 2 SnO 4 interface influences diode electrical properties. [ABSTRACT FROM AUTHOR]

The paper presents a new approach based on the appearance of negative capacitance (NC) at high and low frequencies; previously, researchers agreed that NC only occurred at high or low frequencies. For the first time, we synthesized Au/polypyrrole/MWCNT composite/TiO _2 /Al2O _3 /n-Si/Al structure for use in electronic and supercapacitor applications. The structural, electrical, and dielectric properties were investigated by x-ray diffraction, FTIR, Raman spectroscopy, I-V, and C-V measurements. The results revealed that for all working voltages and temperatures, negative capacitance and conductance occurred at high frequencies between 2 × 10 ^7 and 10 ^7 Hz. Similarly, the phenomena of negative capacitance occurred at low frequencies (100, 10) Hz. The capacitance-voltage experiments were used to perform the analysis of the variation of capacitance and conductance with frequency, voltage, and temperature. The polypyrrole, MWCNT composite /TiO _2 /Al _2 O _3 /n-Si structure exhibits diode behavior and has a high rectification ratio. I-V measurements were used to investigate ideality factors, barrier height, series and shunt resistance#, and rectification ratio.

In this study, a p-type 2 at% lithium-doped nickel oxide (abbreviation L2NiO) solution was prepared using Ni(NO3)2·6H2O, and LiNO3·L2NiO thin films were deposited using an atomizer by spraying the L2NiO solution onto a glass substrate. The sprayed specimen was heated at a low temperature (140 °C) and annealed at different high temperatures and times. This method can reduce the evaporation ratio of the L2NiO solution, affording high-order nucleating points on the substrate. The L2NiO thin films were characterized by X-ray diffraction, scanning electron microscopy, UV–visible spectroscopy, and electrical properties. The figure of merit (FOM) for L2NiO thin films was calculated by Haacke’s formula, and the maximum value was found to be 5.3 × 10−6 Ω−1. FOM results revealed that the L2NiO thin films annealed at 600 °C for 3 h exhibited satisfactory optical and electrical characteristics for photoelectric device applications. Finally, a transparent heterojunction diode was successfully prepared using the L2NiO/indium tin oxide (ITO) structure. The current–voltage characteristics revealed that the transparent heterojunction diode exhibited rectifying properties, with a turn-on voltage of 1.04 V, a leakage current of 1.09 × 10−4 A/cm2 (at 1.1 V), and an ideality factor of n = 0.46.

Significant effort has been devoted to constructing two-dimensional transition metal dichalcogenides-based hybrid heterojunctions with enhanced performance or unique functionalities for versatile device applications in emerging electronics and optoelectronics. In this study, we report the temperature-dependent electronic charge transport characteristics in MoS 2 /p-type Ge heterojunction diodes. From the current-voltage ( I-V ) characteristics of the heterojunction device, it is observed that different transport phenomena can occur depending upon the temperature and bias voltage. The charge transport is dominated by thermionic emission in the high-temperature regime above 300 K, whereas in low-temperature regime below 300 K, the charge transport mechanism transitions from the thermionic emission to the tunneling mechanism associated with trap sites. In particular, the I-V characteristics in the low-temperature regime show a transition from the direct tunneling at a low bias to the Fowler-Nordheim tunneling mechanism at a high bias. This could be well described by the electrical analyses on temperature-dependent I-V behavior and corresponding energy band diagrams. [ABSTRACT FROM AUTHOR]

We present a fundamental experimental study of a microwave assisted chemical bath deposition (MW-CBD) method for Al doped ZnO films. Field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) spectroscopy were used to analyze the microstructures and crystalline structures of these films, respectively. The p-Si/n-ZnO:Al heterojunction diodes were fabricated. The current–voltage ( I–V ) characteristics of these diodes were measured at room temperature. The important electrical parameters such as series resistance, the ideality factor and the barrier height were determined by performing plots from the forward bias I–V characteristics using different methods. The obtained results indicate that Al doping improve the electrical properties of the p-Si/n-ZnO diode. The best rectification properties were observed in the p-Si/n-ZnO:5%Al heterojunction diode, so only capacitance–voltage ( C–V ) measurements of this diode were taken. Electrical parameter values such as series resistance, the built-in potential and the acceptor concentration calculated for this heterojunction diode. [ABSTRACT FROM AUTHOR]

Iron oxide (α-FeO) nanocrystals have been synthesized via the sol-gel technique. The structural and morphological features of these nanocrystals were studied using x-ray diffraction, Fourier transform-infrared spectroscopy and transmission electron microscopy. Colloidal solution of synthesized α-FeO (hematite) was spin-coated onto a single-crystal p-type silicon (p-Si) wafer to fabricate a heterojunction diode with Mansourconfiguration Ag/FeO/p-Si/Al. This diode was electrically characterized at room temperature using current-voltage (I-V) characteristics in the voltage range from −9 V to +9 V. The fabricated diode showed a good rectification behavior with a rectification factor 1.115 × 10 at 6 V. The junction parameters such as ideality factor, barrier height, series resistance and shunt resistance are determined using conventional I-V characteristics. For low forward voltage, the conduction mechanism is dominated by the defect-assisted tunneling process with conventional electron-hole recombination. However, at higher voltage, I-V ohmic and space charge-limited current conduction was became less effective with the contribution of the trapped-charge-limited current at the highest voltage range. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) power devices have been commercialized up to 1.7 kV with operating temperatures up to 573 K. The temperature limitations of SiC devices are generally derived from limitations in packaging and a lack of information on safe operating temperature regimes. Therefore, it is highly desirable to develop reliable temperature sensing techniques that can better take advantage of the SiC devices in high power applications. In this letter, ten gallium nitride (GaN)-on-SiC heterojunction diodes, aiming at high-power and high-temperature sensing applications, were fabricated using concentric ring geometry. These sensors can be monolithically integrated into GaN-on-SiC RF/Microwave power devices with fast-switching frequency and high-power density. The temperature dependent characteristics of the forward voltage drop at fixed current ( VD-{T} ) of these heterojunction devices and their sensitivities (mV/K) are comprehensively characterized in a temperature range from 300 to 650 K. These devices exhibit a high degree of linearity in their VD-{T} characteristics, which indicates the potential to be used as temperature sensors up to 650 K. [ABSTRACT FROM AUTHOR]

Phosphorus doped micro/nano crystalline silicon thin films have been deposited by the filtered cathodic vacuum arc technique at different substrate temperatures (T) ranging from room temperature (RT) to 350 C. The films have been characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy, secondary ion mass spectroscopy, dark conductivity ( σ ), activation energy ( ΔE) and optical band gap (E ). The XRD patterns show that the RT grown film is amorphous in nature but high T (225 and 350 C) deposited films have a crystalline structure with (111) and (220) crystal orientation. The crystallite size of the higher T grown silicon films evaluated was between 17 to 31 nm. Raman spectra reveal the amorphous nature of the film deposited at RT whereas higher T deposited films show a higher crystalline nature. The crystalline volume fraction of the silicon film deposited at higher T was estimated as 65.7 % and 74.4 %. The values of σ , ΔE and E of the silicon films deposited at different T were found to be in the range of 8.84 x 10 − 0.98 ohm cm , 0.06 - 0.31 eV and 1.31-1.93 eV, respectively. A n-type nc-Si/p-type c-Si heterojunction diode was fabricated which showed the diode ideality factor between 1.1 to 1.5. [ABSTRACT FROM AUTHOR]

Tungsten-substituted molybdenum disulfide (Mo 1 − x W x S 2 ) shows excellent semiconductor properties related to the adjustable band gap structure. Mo 1 − x W x S 2 is an n-type semiconductor that has high carrier mobility, adjustable electrical characteristics. Graphene, the thinnest two-dimensional material, shows good thermal conductivity and high carrier mobility. The oxygen adsorption effects of graphene permit precise control of its Fermi level and semiconductor properties. We combined Mo 1 − x W x S 2 films with graphene oxide (GO) in this study to fabricate a pn interface and thoroughly research the energy band and electrical properties for a heterojunction diode. According to the results, the Mo 1 − x W x S 2 electron affinity decreases with increasing x value of tungsten (W) composition (x = 0.0–1.0, Δx = 0.2). The I–V characteristics of the Mo 1 − x W x S 2 /GO heterojunction diodes can be accurately tuned by conduction band bowing effect with different W composition of the Mo 1 − x W x S 2 films. By applying our fabricating method, the Mo 1 − x W x S 2 with different W composition provides a new application of semiconductor device. In this study we using Mo 1 − x W x S 2 films and GO to fabricate a heterojunction diode, it shows different electrical properties with different x value of Mo 1 − x W x S 2 . The Mo 1 − x W x S 2 electron affinity decreases with increasing of W composition x value (x = 0.0–1.0, Δx = 0.2). The Mo 1 − x W x S 2 /GO heterojunction diode I–V characteristics can be accurately tuned using the conduction band bowing effect with different W compositions. Mo 1 − x W x S 2 with different W compositions using our fabrication method provides new semiconductor device applications. [ABSTRACT FROM AUTHOR]

We report a facile all-solution approach for the growth of nanostructured p-CuO and n-ZnO thin films. The influence of annealing temperature on the physical properties of CuO and ZnO thin films was examined. XRD and Raman spectra depict the structural and phase purity of solution grown CuO and ZnO films. The electrical as well as the optical properties of thin films were also studied. The average optical transmission of CuO and ZnO thin films in the visible spectral region was found to be above 80 and 95% respectively. Band gap energy variations on annealing temperature were investigated for CuO as well as ZnO films. Surface morphology analyzed by FESEM shows that the films are very smooth. All solution grown p-n heterojunction using p-CuO and n-ZnO films was fabricated in the structure ITO/n-ZnO/p-CuO/Au which showed rectification behavior with a turn on voltage of 2.5 V and an ideality factor of 3.15. [ABSTRACT FROM AUTHOR]

Printed electronics on flexible substrates requires low temperature and solution processed active inks. With n-type indium-gallium-zinc oxide (IGZO) based electronics maturing for thin film transistor (TFT), we here demonstrate its heterojunction diode with p-copper oxide, prepared by sol-gel method and processed at temperatures compatible with polyimide substrates. The phase obtained for copper oxide is CuO. When coated on n-type oxide, it is prone to develop morphological features, which are minimized by annealing treatment. Diodes of p-CuO films with IGZO are of poor quality due to its high resistivity while, conducting indium-zinc oxide (IZO) films yielded good diode with rectification ratio of 10 4 and operating voltage <1.5 V. A detailed measurement at the interface by X-ray photoelectron spectroscopy and optical absorption ascertained the band alignment to be of staggered type. Consistently, the current in the diode is established to be due to electrons tunnelling from n-IZO to p-CuO. [ABSTRACT FROM AUTHOR]