Papers by Keyword: Leakage Current

Abstract: This study investigates the role of the electrical failure of the SiO₂ film in the breakdown of SiO₂/ZrO₂ and SiO₂/HfO₂ stacks. Our findings indicate that the breakdown is governed by the SiO₂ film, regardless of its thickness. This highlights the importance of carefully considering the interfacial SiO₂ layer when using high-k materials in SiC devices. We demonstrate that thicker SiO₂ layers offer several benefits, including reduced leakage, enhanced thermal stability and electrical strength, and decreased trapping. In contrast, stacks with thinner SiO₂ have a higher effective k value, exploiting the benefits of high-k dielectrics. Our experimental results suggest that a 7 nm SiO₂ layer underlying 30 nm crystalline ZrO₂ or HfO₂ provides optimal performance. Furthermore, we present calculations that reveal the trade-off between SiO₂ thickness, k value, and breakdown voltage for a 50 nm thick dielectric stack. Our results imply that a k value exceeding 20 does not yield significant benefits in 50 nm thick SiO₂/dielectric stacks.

Abstract: This article presents an innovative approach to achieve a high channel mobility for 4H-SiCp-MOSFET via dielectric-semiconductor interface engineering involving atomic layer deposition(ALD) of ultrathin B₂O₃ and SiO₂ stacks. The application of ultrathin boron oxide via ALD introducesa highly manufacturable solution for the passivation of SiC interface. The interface states near valenceband reduces the channel mobility for SiC p-MOSFETs and increases the threshold voltage. Theintroduction of ultrathin B₂O₃ interlayer reduces the threshold voltage and improves the field effectmobility to 12.60 cm²/Vs while the p-MOSFET without the interlayer provides the mobility of 8.91cm²/Vs. This work also includes the optimization of the post-deposition annealing (PDA) conditionsspecific to ultrathin B₂O₃ and bulk SiO₂ dielectric stack to obtain high field effect channel mobilityfor SiO₂/SiC p-MOSFETs.

Abstract: We investigated the electrical and structural effects of silicon (Si), yttrium (Y) and lanthanum (La) doping in 10-45 nm thick hafnium dioxide (HfO₂) films on silicon carbide (SiC) and Si substrates. We show that the introduction of Si dopants leads to a significant enhancement of the electric breakdown field and a reduction of the leakage current density by elevating the crystallization temperature. This effect becomes stronger with higher Si content. In contrast, Y and La doping does not raise T_C but increases the tetragonal and orthorhombic phase portion within the crystalline films and therefore enhances the dielectric constant k. Furthermore, we show that larger grains in crystalline films are associated with a higher leakage current density.

Abstract: The activation of bipolar conduction was investigated for two 4H-SiC 10 kV JBS-diodes which differ in the area ratio between p-doped and n-doped regions (W_s/W_Pin). Quasi-static measurements at low electric current densities (j < 2.5 Acm^-2) were performed in a temperature range between 25°C and 500°C. The lower ratio (W_s/W_Pin) leads to a higher threshold voltage. On the other hand lower electric power density is neccessary to trigger temperature enhanced bipolar activation. Moreover, the lower ratio improves the leakage currents in blocking direction. Dynamic surge current investigations were performed in a temperature range between 25°C and 250°C. The turning voltages, which indicate the transition from unipolar to bipolar conduction, are lower for the diode with smaller ratio (W_s/W_Pin) but the self-heating of the device is more severe in comparison to the other diode with the larger ratio. Both devices are stable under extreme conditions (high temperatures/ surge current) and exhibit special benefits for different applications.

Abstract: This study investigates the effects of micron-sized eggshells filler on resistance to tracking and erosion of silicone rubber composite. Eggshells with particle size from 44 to 53 microns were filled into liquid room temperature vulcanizing (RTV) silicone rubber with 0, 5, 15, 25, and 30 part per hundred of rubber (phr). IEC-60587 inclined plane test (IPT) was employed to appraise the surface tracking resistance. Thermogravimetric analysis was conducted to evaluate its thermal stability. Experimental results revealed an improvement of tracking and erosion resistance due to an addition of eggshells particles. Furthermore, the thermal stability of the composites showed variation in the increasing amount of the filler. The filler indicated that higher thermal stability of eggshells influences the heat resistance of the matrix. An increase of the heat resistance resulted in the ability to slow down tracking growth and erosion in the discharge region.

Abstract: Mechanisms and characteristics of optimized main junction for 4H-SiC trench junction barrier Schottky (T_MJBS) diodes were investigated by theories and experiments. From these simulation and experimental values, we can conclude that T_MJBS device has better reverse performance, such as the best reverse blocking capability and lowest reverse surface leakage current than the conventional JBS and TJBS device while maintaining good forward characteristics. Furthermore, The large area T_MJBS Diodes with high current density show the better reverse characteristics than the small area one at an acceptable forward characteristics. The T_MJBS structure can significantly reduce the influence of the Schottky interface and is more suitable for manufacturing high current density and large area devices.

Abstract: We have investigated the effect of diluting treatment of poly (3,4-ethylenedioxythiophen e):poly (styrene sulfonate)(PEDOT:PSS) solution on the PEDOT:PSS films and the organic polymer solar cells based on poly [4,8-bis (5-(2-ethylhexyl) thiophen-2-yl) benzo [1,2-b;4,5-b0] dithiophene-co-3-fluorothieno [3,4-b] thiophene-2-carboxylate](PTB7-Th):[6,6]-phenyl-C61-butyric acid methyl ester (PC₆₁BM) using PEDOT:PSS polymer as the hole transport layer. The diluted PEDOT:PSS solution by water with 1:1.5 volume ratio was used to fabricate the hole transport layer in the organic solar cell, the fill factor and the shunt resistance of the solar cell can be significantly enhanced compared with the control cell, up to 64% and 949.03Ω·cm², respectively.

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: We investigated the relationship between ion implantation-induced defects and electrical characteristics, especially focusing on the leak failure rate in SiC IEMOSs and PN diodes. It was found that dislocation exists in each leakage point by analyzing identical leak-failed IEMOS by emission microscopy and refraction X-ray topography. The leak failure rate of the PN diodes and IEMOS was improved with an increase in the ion implantation temperature under the implantation and annealing conditions used in this experiment. It is considered that ion implantation-induced defects lead to an increase in leak failure rates, and also enable a decrease in leak failure rates by raising the implantation temperature up to 600 deg.C.

Abstract: The long-term reliability of Schottky pn diodes (SPNDs) on diamond having widely used Ti/Pt/Au electrodes was investigated at 500°C in order to identify degradation phenomena at higher temperatures. A vital degradation event was observed after the passage of about 100 hours in that both forward and reverse currents were progressively reduced. AES depth profiling and X-STEM-EELS analyses revealed that this occurred because the Ti contact material changed to insulating (or semiconductive) TiO₂, causing large series resistance.