Papers by Keyword: Ideality Factor

Abstract: Characterization of electrical parameters of Copper Phthalocyanine dye has been done in the present work. In the context of electrical parameters, the Schottky barrier and ideality factor of the organic device has been measured and the effects of fullerene nanoparticles on these parameters have been studied. Analysis of electrical parameters has been done by the current-voltage characteristics of the device. The influence of fullerene nanoparticles lessens the Schottky barrier to 0.71 eV from 0.75 eV. The current flow is assumed to be injection limited as the Schottky barrier is greater than 0.3 eV - 0.4 eV. The Schottky barrier is also estimated by the Norde method. Norde's method shows lessening of barrier height from 0.70 eV to 0.65 eV under the influence of fullerene nanoparticles. The measured ideality factor value reduces from 3.787 to 1.495 in presence of fullerene nanoparticles. The charge injection mechanism at metal-organic contact gets influenced by the interfacial Schottky barrier height. Decrease in both Schottky barrier and ideality factor attribute to the increase in charge flow and it allows a reduction in the device’s transition voltage from 2.5 V to 1.0 V.

Abstract: Electrical characteristics of semiconductor to metal (S-M) contacts i.e. Schottky contacts, play a vital role towards the performance of the device. The formation of a Schottky contact requires precise thermal treatment, which also affects the electrical characteristic of the junction. In present study, a thin layer of polycrystalline lead sulfide (PbS) was deposited on quartz substrate using chemical bath technique. Metallic electrodes of aluminum and gold were deposited on the each side of the semiconductor film by thermal evaporation method. The aluminum and gold films were 10 nm and 200 nm thick, respectively. Latter, the substrates were thermally treated in air for various durations and the effect of the thermal treatments was evaluated by I-V measurements. It was found that anomalies in the electrical behavior of the S-M contacts were mitigated with the treatments. A change from 0.1 x 10^-6A to 0.4 x 10^-6A in saturation current was observed. Similarly, the ideality factor (at V_th<<V_d) of the S-M contact was 12 on pristine PbS, while it reduced to 2.7 after the thermal treatment, which indicates an improved Schottky contact.

Abstract: Temperature-dependent mechanisms and characteristics of 4H-SiC JBS rectifiers were described by theoretical and experimental results. The forward on-resistance of 4H-SiC JBS rectifier consists of several components, the drift region resistance is most sensitive to temperature than others. Comparing theoretical results with experimental data indicates that the leakage current is mainly affected by the thermionic emission, the image force barrier height lowering and tunneling. At different temperatures and reverse bias, the contribution of barrier lowering and the tunneling to leakage current is not the same. The temperature of critical point decreases with the increasing of the concentration of N_D or the reverse bias voltage V_R. Samples with the doping concentration of N_D=6.5E15cm^-3 and N_D=1E16cm^-3 were manufactured in the same process. The forward I–V-T and reverse I–V-T characteristics of the JBS samples were measured at different temperatures (300K to 523K), and temperature-dependent ideality factor, barrier height and resistance were also analyzed, which are in good agreement with simulation results.

Abstract: Schottky diodes fabricated on free-standing B doped monocrystalline diamond substrate have been investigated. As expected, reverse leakage current due to Schottky barrier lowering has been observed due to the high electric field at the metal-semiconductor interface. Forward current is highest under operating temperatures between 400 and 450K due to incomplete ionization hole mobility dependence on temperature. It is demonstrated that the static device characteristics in the temperature range from 300K to 450K can be modelled by parametrizing an analytical introduced for unipolar SiC and Si diodes.

Abstract: Schottky barrier diodes (SBD) were fabricated on SiC surfaces that had been treated with different surface passivation techniques, so that metal-semiconductor analysis could be used to evaluate the quality of this surface. In this paper, we discuss the results of this study that used Current-Voltage (I-V), Capacitance-Voltage (C-V) and Current-Voltage-Temperature (I-V-T) analysis to look at the impact of untreated oxidation, Nitrous oxide (N₂O) and Phosphorus Silicate Glass (PSG) treatments prior to oxide removal, and the formation of Mo, Ni and Ti diodes. While the results of this study did not reveal any consistent patterns between the different treatments, a Mo diode formed on a surface after PSG treatment, displays exceptionally low leakage (4.44×10^-5 A/cm² at 19°C; 7.26×10^-4 A/cm² at 300°C) given a low barrier height (1.27 eV). Moreover, the barrier heights extracted from C-V analysis before contact annealing show a variation across all the diodes, suggesting that the interface is greatly suffering from Fermi-Level pinning, the result of significant interface traps.

Abstract: This paper reports the temperature dependent DC and RF characteristics of n-GaN Schottky diode simulated using Atlas/Blaze developed by Silvaco. It was found that as the temperature increases from 300K to 900K the forward current decreases due to lowering of the Schottky barrier with an increase in series-resistance and ideality factor. These observations indicates that tunneling behavior dominates the current flow rather than thermionic emission. Furthermore, the breakdown voltage decreases in reverse bias and insertion loss for RF behavior increases with respect to temperature due to the increase in capacitance near diode junction.Keywords: Atlas/Blaze, Schottky barrier, series resistance, ideality factor, insertion loss.

Abstract: In this study, current-voltage (I-V) measurements at room temperature (RT) of platinum (Pt) metal contact combine with n-Al0.08In0.08Ga0.84N thin film which grown epitaxially by molecular beam epitaxy (MBE) technique on sapphire substrate to form Schottky diode have been characterized. Schottky barrier heights of diode related with the high work function metal of Pt electrode was measured and investigated. Pt metal was fabricated using RF-sputtering technique. The effect of annealing temperature ranged from 300 °C to 600 °C on the structural and electrical properties has been studied. The results revealed that in spite of the various annealing temperature used there is no change in XRD diffraction peak observed in Pt contact. Furthermore, at 400 °C the best surface morphology was obtained and the value of SBH and ideality factor (n) was 0.76 eV and, 1.03 respectively. This concludes that at this annealing temperature Pt metal exhibited optimum (I-V) rectifying characteristics of Pt/Al0.08In0.08Ga0.84N Schottky diode.

Abstract: In bulk heterojunction solar cells, the donor and acceptor materials are intimately blended throughout the bulk, so that the excitons generated will reach the interface within their lifetime. In this work, Rosebengal (RB) is used as the donor material and nanocrystalline Titanium dioxide (nc TiO₂) as the acceptor material. Devices with device structure ITO/RB:TiO₂/Ag are prepared and their optical and electrical properties are compared at different temperatures. Optical absorption spectroscopic analysis shows that the absorption of Rose bengal ranges from 650-800 nm corresponding to a band gap of 1.98 eV. Cyclic voltametric analysis, and photo voltaic properties are analysed. Using simulation, the dark current parameters such as ideality factor (n), mobility (µ) potential barrier (φ_b) and carrier concentration are extracted and tabulated.

Abstract: Electrical behaviors of light-emitting diodes (LEDs) prepared by wide-band GaN material were measured accurately using alternating-current (AC) small-signal together with an I-V plot. An abnormal negative capacitance (NC) was observed in all measurend LEDs, and at the same voltage the lower the frequency is, the more obvious NC is. Form the slopes of ln(I)-V plot and the relation between NC and voltage the ideality factor was approximately obtained.

Abstract: The current-voltage (I-V) characteristics of most industrial silicon solar cells deviate rather strongly from the exponential behavior expected from textbook knowledge. Thus, the recombination current may be orders of magnitude larger than expected for the given material quality and often shows an ideality factor larger than 2 in a wide bias-range, which cannot be explained by classical theory either. Sometimes, the cells contain ohmic shunts although the cell’s edges have been perfectly insolated. Even in the absence of such shunts, the characteristics are linear or super-linear under reverse bias, while a saturation would be classically expected. Especially in multicrystalline cells the breakdown does not tend to occur at -50 V reverse bias, as expected, but already at about -15 V or even below. These deviations are typically caused by extended defects in the cells. This paper reviews the present knowledge of the origin of such non-ideal I-V characteristics of silicon solar cells and introduces new results on recombination involving coupled defect levels.