Diode Parameters Research Articles

The size effect on the optical-electrical properties of Cu2S/CdS thin film towards the performance on Ag/p-Cu2S/n-CdS/ATO heterojunction diode

Here we report, room temperature deposition of Cu2S/CdS thin film on antimony doped tin oxide(ATO) substrate through spray pyrolysis and dip coating technique. The effect of size on the deposited Cu2S/CdS thin films and its heterojunction parameters are extensively investigated. The sizes of the thin film are estimated through field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images. The optical properties of the Cu2S/CdS thin film are studied using UV–Vis–NIR spectrometer. It is found that increase in the size, the transmittance decreases, consequently the band-gap energy decreases from 2.92eV to 2.86eV. The refractive index and the dielectric constant are calculated from the optical measurements. In addition, the dispersion of the refractive index is discussed in terms of the Wemple-DiDomenico single-oscillator model. The oscillator parameters such as optical dispersion energies, dielectric constant, the average value of oscillator strength, wavelength of single oscillator, plasma frequency and lattice energy are evaluated. To examine the size-dependent electrical parameters of Cu2S/CdS thin film, high-quality vacuum evaporated silver (Ag) is used as front contact. The current-voltage (I–V) curves of the Ag/p-Cu2S/n-CdS/ATO/glass heterojunction device are measured under dark mode at standard testing conditions (STC). The dark measurements of the fabricated device are investigated through the conventional I–V method, Norde method, and Cheung method. It is observed that the potential height of the heterojunction device decreases from 0.89 to 0.76 with an increment of the size of Cu2S/CdS thin films. It is observed that the size strongly influenced the diode parameters viz. ideality factor, saturation current, barrier height, series, and shunt resistance performance.

Efficient Cd-Free Flexible CZTSSe Solar Cells with Quality Interfaces by Using the Zn1–xSnxO Buffer Layer

The severe carrier recombination at the CZTSSe/CdS heterojunction interface and high toxicity of Cd limit the further development of flexible Cu2ZnSn(S, Se)4 (CZTSSe) solar cells. Here, we apply a suitable and environmentally friendly Zn1–xSnxO (ZTO) buffer layer to suppress the interface recombination in the flexible solar cell for the first time. The ZTO buffer layers with good qualities have been successfully obtained by varying the Sn/(Zn + Sn) value. The solar cell has obtained an efficiency of 8.7%, which is the highest efficiency reported for a Cd-free flexible CZTSSe solar cell so far. The optimal device has more ideal diode parameter values, indicating that the interface quality is significantly improved. The VOC-T characteristic demonstrates that the interfacial recombination of flexible ZTO devices has been greatly reduced. The theoretical simulations show that the flexible CZTSSe devices with optimal ZTO layers achieve good band alignment to reduce the interface recombination, elucidating the intrinsic link between the band structure and the device performance. This investigation provides a solution to achieve environmentally friendly and efficient flexible CZTSSe solar cells by designing the interface engineering of the absorber/buffer heterojunction in solar cells.

Influence of ion cleaning of front facet of 9xx nm InGaAs/AlGaAs/GaAs diode lasers on their maximal output power

This paper reports on the study of the effect of ion cleaning of emitting cleaved facet of 9xx nm laser diodes based on InGaAs/AlGaAs/GaAs on their limiting radiation power. Measured maximal power and the percentage of laser diodes with a visual manifestation of catastrophic optical damage in the active region were analyzed. It was found that short-term (1 min) low-energy treatment with argon and hydrogen ions does not lead to changes in the parameters of laser diodes, while treatment with nitrogen ions results in a decrease in the maximal output power and an increase in the probability of catastrophic optical damage. It is also shown that the use of an ion source based on electron cyclotron resonance leads to better results compared to a End Hall source or radiofrequency source with inductively coupled plasma, due to the lower energy of the ions. Keywords: Ion cleaning, laser diode, catastrophic optical damage, maximal output power, passivation, nitridization.

Pressure as the device for changing electric parameters of Schottky diodes based on Si mono crystal

The analysis of investigations carried out on studying influence of all-around pressure to Schottky diodes based on n-Si<Bi> construction characteristics has been presented. It has been revealed that before the pressure influence the diodes capacitance is growing monotonically on the increasing temperature, at the same time after depressurization it loses monotony and has the maximal value about 50 pF on 30 oC temperature. It has been shown that the diodes conductivity is growing slowly on temperature both under the pressure and after its removal. When the pressure up to 12 kBar is acting to n-Si<Ni> diodes structures then we deal with monotonic growing the resistivity. Further, when pressure is growing in range of 12 and 60 kBar then changes in n-Si<Ni> samples resistivity on influence pressure has not monotonic character with a maximum value by P ≥ 35 kBar.

Влияние ионной очистки поверхности излучающего скола 9хх нм лазерных диодов на основе InGaAs/AlGaAs/GaAs на их предельную мощность излучения

This paper reports on the study of the effect of ion cleaning of emitting cleaved facet of 9xx nm laser diodes based on InGaAs/AlGaAs/GaAs on their limiting radiation power. Measured maximal power and the percentage of laser diodes with a visual manifestation of catastrophic optical damage in the active region were analyzed. It was found that short-term (1 min) low-energy treatment with argon and hydrogen ions does not lead to changes in the parameters of laser diodes, while treatment with nitrogen ions results in a decrease in the maximal output power and an increase in the probability of catastrophic optical damage. It is also shown that the use of an ion source based on electron cyclotron resonance leads to better results compared to a End Hall source or radiofrequency source with inductively coupled plasma, due to the lower energy of the ions.

Исследование технологии изготовления мощных ИК (850 nm) светодиодов, получаемых методом переноса AlGaAs-GaAs-гетероструктуры на подложку-носитель

Development of lift-off technique of AlGaAs/GaAs heterostructures, grown by the MOCVD technique, to GaAs carrier-substrate using silver-containing paste or Au-In compound has been carried out. Forming process of frontal ohmic contact to GaAs n-type conductivity based on contact systems Au(Ge)/Ni/Au and Pd/Ge/Au with specific contact resistivity 2-5·10-6 Ом·см2 has been investigated. Analyzed was the influence of heterostructure lift-off technique and forming process of frontal ohmic contact on the IR light-emitting diodes parameters: minimum light-emitting diodes (1mm2 square) series resistance was 0.16 Ohm. Optical power 270 mW at current 1.5A has been achieved.

Investigation of power IR (850 nm) light-emitting diodes manufacturing by lift-off technique of AlGaAs-GaAs- heterostructure to carrier-substrate

Development of lift-off technique of AlGaAs/GaAs- heterostructures, grown by the Metalorganic vapour-phase epitaxy, to GaAs carrier-substrate using silver-containing paste or Au-In compound has been carried out. Forming process of frontal ohmic contact to GaAs n-type conductivity based on contact systems Au(Ge)/Ni/Au and Pd/Ge/Au with specific contact resistance (2-5)·10-6 Ω·cm2 has been investigated. Analyzed was the influence of heterostructure lift-off technique and forming process of frontal ohmic contact on the IR light-emitting diodes parameters: minimum light-emitting diodes (1 mm2 square) series resistance was 0.16 Ω. Optical power 270 mW at current 1.5 A has been achieved. Keywords: AlGaAs/GaAs- heterostructure, light-emitting diode, transfer to carrier-substrate, Au--In- compound, ohmic contacts.

Micro size developed TiO2-CdO composite film: Exhibits diode characteristics

TiO2-CdO composite thick film deposited on Si substrate was characterised for diode applications. X-ray Diffraction (XRD) confirms the existence of anatase phase of TiO2 and a cubic phase of CdO with a maximum diffraction at (101) plane. Porous surface morphology was recognized from scanning electron microscope (SEM).The UV–visible spectra have revealed a direct band gap of 3.17 eV while photoluminescence spectra and CIE diagram show blue-green emissions at 2.33 eV. Diode parameters such as ideality factor (n) and barrier height (Φb) have been calculated with the aid of I-V characteristics. Thus extracted results indicate the suitability of TiO2-CdO composite thick films for photovoltaic applications.

Phosphorous-doped graphene as an efficient interfacial layer material for application in solution-processed photodetectors

This work demonstrates solution-processed photodetectors (PDs) with perovskite as the active layer material, reduced graphene oxide as the hole transport layer and phosphorus-doped graphene (P-G) as the interfacial layer. High detectivity of over 1012 Jones was attained with PDs fabricated with the P-G layer, suggesting the great potential of the P-G layer as an additional dark current blocking layer. Analysis of the diode parameters indicated that this improved optoelectronic performance was attributed to decreased recombination, which resulted from a decrease in interface and trap defects and improved surface morphology, as evident from the field emission scanning electron microscope images. Recombination resistance, carrier lifetime and charge transport resistance were estimated using impedance spectroscopy analysis. It was observed that suppressed recombination due to improved surface morphology, including large grain size, is the main reason for the enhanced optoelectronic performance of PDs fabricated with the P-G layer. This work demonstrates that the use of an additional blocking/interfacial layer can be an effective strategy to improve the performance of solution-processed optoelectronic devices.

Parameter extraction of photovoltaic models using atomic orbital search algorithm on a decent basis for novel accurate RMSE calculation

In the available literature, there are several methods and techniques are employed to extract the unknown parameters of solar cell. The performance of the method used is validated on the basis of Root Mean Square Error (RMSE) value. This work aims to promote a decent basis for proper investigation and the implementation of an optimization algorithm to extract solar unknown parameters. In this work, the true value of RMSE is calculated for the single diode model of the RTC France solar cell using 30 different methods published in several literatures. The obtained results show that the approach of calculating RMSE is not precise in most of the published literature. The Atomic Orbital Search algorithm is proposed as a new metaheuristic optimisation method to extract the parameters of a single diode, double diode and three diode models for RTC France and PVM752 GaAs thin film solar cell. Last, the performance of the proposed algorithm is compared with other different optimisation algorithms. It is observed that the proposed algorithm gives best results with less RMSE as compared to other algorithms. This work intends to provide a solid foundation for thorough analysis and implementation of an optimization technique to extract unknown solar parameters.

Investigation of the Electrical Properties of PAN-GO/p-Si Schottky Diode

In this article, the electrical properties of PAN-GO/p-Si Schottky diode were investigated in the dark at room temperature. Field-emission scanning electron microscopy (FE-SEM) was utilized to study the structure of the PAN:GO interfacial layer. Diode parameters were calculated according to thermionic emission theory. By using the I-V characteristic of the prepared PAN-GO diode, the ideality factor (n), barrier height (ФB) and series resistance (Rs) values were evaluated with the I-V method and Norde functions. The barrier height values calculated with the I-V and Norde function were found to be 0.767 eV and 0.761 eV, respectively. The ideality factor was found to be 2.078 from the I-V method. The series resistance value of the diode was calculated as 42 kΩ using Norde functions. Energy-dependence profile of interface state density was determined from the current-voltage characteristics by considering the voltage-dependence of barrier height and ideality factor The interface state density (Nss) values of the PAN-GO/p-Si Schottky diode are 9.5x1011 eV-1cm-2 for 0.35-Ev eV and 1.03x1011 eV-1cm-2 for 0.74-Ev eV. Experimental results approved that the PAN-GO interfacial layer improved the performance of metal-semiconductor Schottky diode in respect of low ideality factor, interface state density, and high barrier height and rectification rate.

Diode performance of silica nanoparticles extracted from Pleurosira laevis diatom frustules

In this work, we measured the I-V characteristics of silica nanoparticles (SNPs) extracted from the Pleurosira laevis diatom and deposited on top of a p-type Si(111) wafer. The electric response of the SNPs-based diode is found to be more sensitive to thermal and optical power than the fresh frustules-based diode by about 3 and 5 times, respectively. Moreover, the chemically processed SNPs exhibit better diode parameters, i.e. for them the ideality factor is closer to 1, the series resistance is 3 times lower, and the shunt resistance is 4 times higher than those of the fresh frustules silica. It is stimulating to use the extracted SNPs in innovative electronic and optoelectronic applications as an abundant, cheap, and easy-to-process material.

Dark conduction mechanisms of PTQBDT based heterojunction diode

Al:LiF/PTQBT:PCBM/PEDOT:PSS/ITO/glass organic-based diode is fabricated with different weight ratios in PTQBT:PCBM active layer. The diodes D1, D2 and D3 are prepared using the precursor solution for spin coating process as 1:2, 1:3 and 1:4, respectively. Under dark, main diode parameters are extracted by conventional thermionic emission theory using the results of measurements. Parasitic resistance contribution, non-ideal barrier height formation and high values of ideality factor indicate possible effects of space charge limited current flow mechanism on forward biased characteristics. At saturated voltage region, series resistances are calculated and the results are evaluated according to Cheung’s method. The possible voltage sharing between interface layer and depletion region are also investigated by analysis of density of interface states. In addition, field effect is found in a major role on the reverse current flow and the mechanism is evaluated according to Schottky-Richardson model.

Design construction and performance of nanostructured p-Cu2S/n-CdS junction diode

Here we report the deposition of Cu2S/CdS thin-film on FTO substrate through spray-pyrolysis technique. The sizes of the thin-film are estimated through field-emission scanning electron microscopy(FESEM) images,exhibited that the films are mono-dispersed, and nearly spherical with the average size lies in the range of 50 nm to 100 nm, which increases with increasing the temperature. The effect of temperature on the performance of Sn/Cu2S/CdS/FTO/glass hetrojunction diodes are analyzed through I–V measurement. The diode parameters such as potential height, leakage current, ideality factor and series-shunt resistance are calculated through conventional thermionic-emission, Cheung and Norde models. It is observed that the ideality factor decreases from 1.31 to 1.12 and potential height increases from 0.79 to 0.86, as temperature increases from thermionic emission model. The diode parameter values estimated from these three different methods are in good agreement.

Design of multi-channel AlGaN/GaN Schottky diode for improving rectification efficiency in microwave power transmission

Schottky barrier diode (SBD) is the core of the rectification circuit in the microwave power transmission (MPT) system and suitable for high-power RF-DC conversion. However, the rectification efficiency of current commercial SBD cannot meet the requirements of the MPT system. Therefore, this paper proposes a microwave rectification circuit based on the multi-channel AlGaN/GaN SBD. The effect of diode parameters on the rectification efficiency has been investigated, such as the number of channels, the length of anode field plate (LAFP) and the thickness of insulation layer. Simulation results show that multiple AlGaN/GaN heterojunctions can significantly reduce the on-resistance of SBD and improve the rectification efficiency. The power capacity of SBD can be increased withthe optimised LAFP and the thickness of insulation layer, which enables efficient microwave rectification in high power applications. High RF-DC rectification efficiency of 85.1% is obtained at the input power of 33 dBm. The rectification efficiency exceeds 60% over a wide input power range (14–38 dBm). The results demonstrate the great potential of multi-channel AlGaN/GaN SBD for high-power MPT application.

Effect of the contact area on the electrical characteristics of the Ti/6H–SiC (n) Schottky diode

In this paper, we investigated three different sizes (1.6 × 1.6, 1.6 × 0.4 and 0.4 × 0.4 mm2) of Ti Schottky diodes on n-type 6H–SiC epitaxial layers using current-voltage-temperature I–V-T measurements. At room temperature, Schottky contacts I–V characteristics are influenced by the dimensions of the contact area, the bigger and medium diodes present near-ideal behavior following the thermionic emission current theory. However, the characteristics of the smaller diode are affected by the presence of two barrier heights, which can be identified as abnormal interface inhomogeneities. The basic Schottky diode parameters are extracted by the standard Least Mean Square LMS method, recalculated and explained by the thermionic emission current theory (TE) using the Newton-Raphson method.An exhaustive analysis was carried according to the temperature in a wide range 77–500 K which also shows a deviation from the ideality at lower temperatures, thus suggesting that an inhomogeneous barrier has indeed formed and this for all three contacts.The I–V-T analysis allowed us to evaluate the Richardson constant A* in the Ti/6H–SiC Schottky diode by applying the barrier height inhomogeneities correction with the Gaussian distribution. It was close to the theoretical value.

Investigation of photon-induced effects on some diode parameters and negative capacitance of the Schottky structure with Zn-doped organic polymer (PVA) interface

Variation in the electrical parameters depending on illumination and the formation of negative capacitance (NC), and inductive behavior (IB) of Schottky structures interlaid with Zn:PVA, were executed by current/impedance-voltage (I/Z-V) measurements in the dark and under 200 mW cm−2 illuminance. To designate the voltage or calculation method effects on the ideality factor (n), barrier height (BH-Φ B ), and series resistance (R s ), these parameters were extracted from different methods. These parameters extracted through the Thermionic-emission (TE) theory, Ohm’s law, Norde and Cheung functions were compared with each other. The reverse bias ln(I R )−V R 0.5 plots were also drawn to designate the validity of Poole-Frenkel and Schottky emissions. In Z-V measurements, NC and related IB phenomena were observed at 500 kHz-fixed frequency in the dark and under illuminance. The interface states (D it ) variation depending on energy and voltage was obtained using I-V and C/G-V measurements and related equations. The calculations of the diffusion-potential (V D ), acceptor-atoms (N A ), Fermi-energy (E F ), and Φ B (C-V) values were performed by fitting the observed linear in the reverse bias C −2 -V plot. A detailed analysis of NC was performed via the drawn C/(G/ω)-I plots for positive voltages. All experimental results show that the used calculation method, illumination, and voltage are highly effective on the electrical parameters.

Structural characterizations and photoelectric performance of non-crystalline boron subphthalocyanine chloride films/FTO for photodiode applications

A thin film of Boron subphthalocyanine chloride (B-subPcCl) has been deposited with different thicknesses, up to 300 nm, on the conductive fluorine-doped tin oxide (FTO) substrates using an evaporating coating unit. The structure of the fabricated film has been studied using X-ray diffraction (XRD) and atomic force microscopy (AFM). XRD confirmed that B-subPcCl films are an amorphous material, and AFM showed that the fabricated thin films' grain sizes increased from 123.5 to 206.5 nm as the film thickness from 76 to 300 nm. The optical properties such as reflectance, transmission, absorption index, and refractive index have been characterized by the analysis of the spectrophotometric measurements. As a result of the thin film thickness increase up to 300 nm, the energy bandgap was decreased by about 10%. The refractive index shows the lowest value at 1680 nm due to the polarization decrease. The I–V characteristics of the FTO/B-subPcCl/Au photodiode were investigated in the dark and under various light illumination intensities. The rectification ratio of our diode was 199 and 59 in dark and light, respectively. The thermionic emission theory was used to calculate the main diode parameters. The current architecture, FTO/B-subPcCl/Au, demonstrated a good light response, with estimated values of responsivity of about 4.2 × 10−6 A/W at -1 V and illumination intensity of 80 mW/cm2.

Research on Lightning Overvoltage Characteristics of High-Voltage Diode Rectifier

Failure of the high-voltage diode rectifier caused by lightning will cause huge losses. The traditional analysis of overvoltage induced by the high-voltage diode rectifier shell under lightning stroke cannot adapt to the overvoltage process caused by lightning stroke-induced conduction invading the inside of the high-voltage diode rectifier. Therefore, this paper proposes to establish a high-frequency equivalent model of the core components of the high-voltage diode rectifier, including diodes, reactors, transformers, and overhead lines. On this basis, a lightning overvoltage model of lightning-induced conduction into the high-voltage diode rectifier is built, and the transient process of diode lightning overvoltage under the constraint of reverse recovery charge is analyzed. Then, we describe the transient distribution of overvoltage in high-voltage diode rectifiers caused by lightning stroke. The transient distribution of overvoltage induced by lightning in series diodes under different diode equivalent models is analyzed by simulation. The simulation results show that the inconsistent parameters of series diodes can easily lead to diode damage due to uneven voltage distribution when lightning strikes. Therefore, this paper puts forward a scheme to reduce lightning damage, including selecting diodes with the same parameters and adding fast-melting fuses at the transformer’s secondary side and in front of the series diode bridge arm. The simulation shows that the scheme proposed in this paper can effectively prevent the high-voltage diode rectifier from being damaged by lightning strikes.

Investigation of Charge Transport Properties in VTP: PC71BM Organic Schottky Diode

In this work, the charge transport properties of organic vanadyl 3,10,17,24-tetra-tert-butyl-1,8,15,22-tetrakis(dimethylamino)-29H,31H phthalocyanine (VTP) were investigated. The I-V profile demonstrated by single VTP shows a rectifying behavior, and Schottky diode parameters such as the ideality factor, barrier height, shunt, and series resistance were calculated. Further, the charge transport behavior of single-layer VTP and its blend with phenyl C71 butyric acid methyl ester (PC71BM) was evaluated using the I-V conventional method and diode analysis. In addition, the optimized diode properties of VTP: PC71BM were chosen to evaluate its photovoltaic effect. The current density-voltage (J-V) characteristics were evaluated in both dark and light conditions to determine the key parameters of the photovoltaic effect. The results indicate the optimized VTP: the PC71BM composite blend yielded a relatively low photovoltaic efficiency. However, due to the presence of extended ligands, it gives a very good sensitivity when applied in the organic photodetector device, as reported in our previous work.