Higher output power from BARITT diodes using ion implantation

Phosphorus-ion implantation has been used in simple m-n-p+ Baritt diodes to controllably modify electric-field profiles and give increased output power.     

SiC device edge termination using finite area argon implantation

In this paper, the results obtained with limited area amorphization by argon ion-implantation at the periphery of 6H-SiC Schottky barrier diodes are reported. It is demonstrated that only 50 μm of implant region is required at the periphery to obtain ideal plane parallel breakdown voltages. The leakage current at small reverse bias voltages was found to be directly proportional to the implant area     

Bulk unipolar camel diodes formed using indium implantation into silicon

Bulk unipolar camel diodes have been made by implanting indium and arsenic into 〈100〉 silicon at low energies. It is found that a wide range of barrier heights can be obtained simply by selecting the indium energy, ideality factors being <1.1 in some cases, and leakage currents <150 nA cm^-2following activation of the implants at 650°C.     

SiC JBS二极管和SiC MOSFET的空间辐照效应及机理

基于第六代650 V碳化硅结型肖特基二极管(SiC JBS Diode)和第三代900 V碳化硅场效应晶体管(SiC MOSFET),开展SiC功率器件的单粒子效应、总剂量效应和位移损伤效应研究。20～80 MeV质子单粒子效应实验中,SiC功率器件发生单粒子烧毁(SEB)时伴随着波浪形脉冲电流的产生,辐照后SEB器件的击穿特性完全丧失。SiC功率器件发生SEB时的累积质子注量随偏置电压的增大而减小。利用计算机辅助设计工具(TCAD)开展SiC MOSFET的单粒子效应仿真,结果表明,重离子从源极入射器件时,具有更短的SEB发生时间和更低的SEB阈值电压。栅-源拐角和衬底-外延层交界处为SiC MOSFET的SEB敏感区域,强电场强度和高电流密度的同时存在导致敏感区域产生过高的晶格温度。SiC MOSFET在栅压偏置(U_GS=3 V,U_DS=0 V)下开展钴源总剂量效应实验,相比于漏压偏置(U_GS=0 V,U_DS=300 V)和零压偏置(U_GS=U_DS=0...     

SiC power Schottky and PiN diodes

The present state of SiC power Schottky and PiN diodes are presented in this paper. The design, fabrication, and characterization of a 130 A Schottky diode, 4.9 kV Schottky diode, and an 8.6 kV 4H-SiC PiN diode, which are considered to be significant milestones in the development of high power SiC diodes, are described in detail. Design guidelines and practical issues for the realization of high-power SiC Schottky and PiN diodes are also presented. Experimental results on edge termination techniques applied to newly developed, extremely thick (e.g., 85 and 100 μm) 4H-SiC epitaxial layers show promising results. Switching and high-temperature measurements prove that SiC power diodes offer extremely low loss alternatives to conventional technologies and show the promise of demonstrating efficient power circuits. At sufficiently high on-state current densities, the on-state voltage drop of Schottky and PiN diodes have been shown to be comparable to those offered by conventional technologies     

EBIC analysis of SiC mesa diodes

Mesa etched p⁺n 6H-SiC diodes were investigated using EBIC. The EBIC signal was analysed using TMA Medici and Monte Carlo simulations. Space charge characteristics obtained from EBIC and static device simulations were compared. Surface charge density and minority carrier lifetime of the low doped n-type region were determined. The charge generation volume is described by an analytical approximation based on calculations using single scattering Monte Carlo simulation code. Results show large positive surface charge density of the order of 1×10¹³ q/cm² present at the n-type SiC/SiO₂ interface. A common origin of the surface charge on n- and p-type SiC is suggested. The EBIC method, combined with simulation tools, was confirmed to be a valuable diagnostic tool for study of the junction termination and passivation in SiC devices.     

AuSiC Schottky barrier diodes

Results of the experimental study of Au n-type SiC Schottky barrier diodes at room temperature are presented. The diodes are fabricated by vacuum-evaporating gold on chemically etched n-type hexagonal (6H) SiC surfaces and exhibit excellent forward current vs voltage characteristics with the exponential factor n of about 1·07±0·02 for voltages between 0·35 and 0·85 V. The linear part of the characteristic, in a semi-logarithmic plot, extends over seven orders of magnitude in current. The forward current-voltage characteristics are found to agree quantitatively with the theory based on thermionic emission with the barrier height modified by image force lowering. The Schottky barrier height is determined from three independent techniques: differential capacitance vs voltage, photoresponse, and forward current vs voltage methods. The barrier height deduced from the three methods is about 1·40±0·05 V.     

Si整流器与SiC二极管:谁与争锋硅器件降低了成本且/或提高了设备性能

在当今的电气设备中,功率半导体和电抗式元件(电容和电感)随处可见.它们在正常工作过程中会在为其供电的交流电线上产生两种不希望出现的副作用.     

Characterization of SiC Schottky diodes at different temperatures

The emergence of silicon carbide (SiC) based power semiconductor switches, with their superior features compared with silicon (Si) based switches, has resulted in substantial improvement in the performance of power electronics converter systems. These systems with SiC power devices have the qualities of being more compact, lighter, and more efficient; thus, they are ideal for high-voltage power electronics applications. In this study, commercial Si pn and SiC Schottky diodes are tested and characterized, their behavioral static and loss models are derived at different temperatures, and they are compared with respect to each other.     

Power cycling analysis method for high-voltage SiC diodes

This work describes a novel analysis method for the power cycling test, developed for high-voltage and temperature silicon carbide diodes. The silicon carbide devices working at temperatures beyond 170 °C, the maximum temperature rating for silicon devices, need specific reliability tests adapted to high temperature operation of this new generation of power devices. The specificity of the further presented method consist in the use of 10 ms sinusoidal power current pulses that are able to evidence the temperature developed inside the diode during the power pulse, the temperature characteristic delay versus the applied current and the temperature calibration method. Moreover, this overall method is able to evidence the transformations occurred in the bonding contact and the dye attach.     

SiC devices for advanced power and high-temperature applications

Silicon carbide (SiC) process technology has made rapid progress, resulting in the realization of very promising electronic devices and sensors, enabling advanced solutions in power industry and mobile systems. In particular, for electronics working under harsh environmental conditions, SiC devices reach unprecedented performance. Transfer to production has already started for some applications     

High temperature long term stability of SiC Schottky diodes

Reliability of Silicon Carbide (SiC) power devices is still an open problem, preventing a wider application of such a promising technology. Moreover, specific reliability assessment procedures must be developed for SiC devices, as they are designed to work at temperatures well beyond those of standard Silicon devices. A detailed investigation about the reliability of 600 V, 6 A Silicon Carbide Schottky diodes is accomplished along this paper. It is based on an extensive set of high temperature reverse bias endurance tests, performed on devices featuring different packages. Only small forward voltage drop and reverse current drifts have been recorded after a 1000 h long test, confirming the parametric stability and the reliability level reached by last generation SiC Schottky diodes. Moreover, devices assembled in TO220 package without flame retardant components in the molding compound performed better than devices assembled in other TO220 packages, or assembled in hermetic TO3 package, pointing out the role played by the interface between the green molding compound and the top passivation layer in the long term parametric stability.     

Fluorescent SiC and its application to white light-emitting diodes

Fluorescent-SiC(f-SiC),which contains donor and acceptor impurities with optimum concentrations, has high conversion efficiency from NUV to visible light caused by donor-acceptor-pair(DAP) recombination. This material can be used as a substrate for a near UV light-emitting diode(LED) stack,and leads to monolithic white LED device with suitable spectral property for general lighting applications.In this paper,we describe basic technologies of the white LED,such as optical properties of f-SiC substrate,and epitaxial growth of NUV stack on the f-SiC substrate.     

The guard-ring termination for the high-voltage SiC Schottkybarrier diodes

In this report, we propose the guard-ring structure as the edge termination for the high-voltage SiC Schottky barrier diodes. The local oxidation process is used to form the mesa of a p-n junction as the guard-ring. The comparison between the Al/Ti Schottky barrier diodes with and without the guard-ring indicates the effectiveness of the guard-ring to relax the electric field, from the results that the breakdown voltage is about two times larger with high yield     

Static and dynamic characterization of large-areahigh-current-density SiC Schottky diodes

The static and dynamic characteristics of large-area, high-voltage 4H-SiC Schottky barrier diodes are presented. With a breakdown voltage greater than 1200 V and a forward current in excess of 6 A at 2 V forward bias, these devices enable for the first time the evaluation of SiC Schottky diodes in practical switching circuits. These diodes were inserted into standard test circuits and compared to commercially available silicon devices, the results of which are reported here. Substituting SiC Schottky diodes in place of comparably rated silicon PIN diodes reduced the switching losses by a factor of four, and virtually eliminated the reverse recovery transient. These results are even more dramatic at elevated temperatures. While the switching loss in silicon diodes increases dramatically with temperature, the SiC devices remain essentially unchanged. The data presented here clearly demonstrates the distinct advantages offered by SiC Schottky rectifiers, and their emerging potential to replace silicon PIN diodes in power switching applications     

Fluorescent SiC and its application to white light-emitting diodes

Fluorescent-SiC (f-SiC), which contains donor and acceptor impurities with optimum concentrations, has high conversion efficiency from NUV to visible light caused by donor-acceptor-pair (DAP) recombination. This material can be used as a substrate for a near UV light-emitting diode (LED) stack, and leads to monolithic white LED device with suitable spectral property for general lighting applications. In this paper, we describe basic technologies of the white LED, such as optical properties of f-SiC substrate, and epitaxial growth of NUV stack on the f-SiC substrate.     

High-power and high-temperature operation of Mg-doped AlGaInP-based red laser diodes

This paper reports on high-power and high-temperature operation of an AlGaInP-based high-power red laser diode with magnesium (Mg)-doped quaternary-alloy cladding layer. The use of Mg dopant with small diffusion coefficient enables abrupt doping profiles as well as high carrier concentrations when compared to conventional zinc (Zn) dopant. It was also found that the metal-organic vapor phase epitaxial (MOVPE) growth of Mg-doped quaternary AlGaInP alloy is not affected by so-called reactor memory effects, while unintentional incorporation of Mg is observed in GaAs after the growth of Mg-doped GaAs layers. The higher carrier concentration in the p-type cladding layer enhanced carrier confinement in the active layer so that device performance at high temperature is improved. The abrupt doping profile suppressing dopant diffusion into the active layer eliminates the nonradiative recombination in the active layer resulting in higher external quantum efficiency. The characteristic temperature of the Mg-doped red laser with a lasing wavelength of 659 nm is as high as 167 K while the Zn-doped laser exhibits a temperature of 127 K. High kink-free output power of 150 mW is achieved at 75/spl deg/C.     

Report on 4H–SiC JTE Schottky diodes

4H–SiC Schottky diodes with and without Junction Terminate Extension (JTE) have been fabricated using Ni for contact and boron for p+ implant. Electrical characterization showed a rectifying behaviour in the on-state. In the reverse mode, the un-terminated Schottky diode demonstrated a breakdown voltage of approximately 200 V, while the JTE structure exhibited a significant improved breakdown performance, and the blocking voltage over 450 V. Optical microscope examination revealed the surface flashover failure located at the metal contact periphery for the un-terminated Schottky diode, while the JTE structure failed in the central area of the metal contact. Both the experimental and theoretical analyses confirmed the JTE structure enhancement on the reliability for SiC Schottky diode performance in reverse mode.     

Characteristics of Ni/SiC Schottky diodes grown by ICP-CVD

A Ni/SiC Schottky diode was fabricated with an α-SiC thin film grown by the inductively coupled plasma chemical vapor deposition, ICP-CVD method on a (1 1 1) Si wafer. The α-SiC film was grown on a carbonized Si layer that the Si surface had been chemically converted to a very thin SiC layer by the ICP-CVD method at 700 °C. To reduce defects between the Si and α-SiC, the surface of the Si wafer is slightly carbonized. The film characteristics of α-SiC were investigated by employing TEM and FT-IR. A sputtered Ni thin film was used for the anode metal. The boundary status of the Ni/SiC contact was investigated by AES as a function of annealing temperature. It is shown that the ohmic contact could be acquired below 1000 °C annealing temperature. The forward voltage drop of the Ni/α-SiC Schottky diode is 1.0 V at 100 A/cm². The breakdown voltage is 545 V which is five times larger than the ideal breakdown voltage of a silicon device. Also, the dependence of barrier height on temperature was observed.