Ing. Vít Záhlava, CSc.

This article deals with minimizing errors caused by selection of passive components from production preferred values. For example, the E24 series of passive components only has 24 values per a decade, so the exact calculated value of the components must be rounded to the nearest value in the series. This rounding to an inaccurate value creates the error. The article describes several methods of minimizing this error and introduces a new method called “Effective Component Selection Method” that eliminates disadvantages of the previous methods. The principle is to select the components in such a way that the errors caused by the rounding of the individual circuit components cancel each other out in the resulting function of the circuit. This is achieved by optimization and by using the circuit’s degrees of freedom that are independent on its required function.

This paper deals with the operation of neutron irradiated 1700V SiC V-JFET in proposed DC-DC converters. The influence of irradiated V-JFET on the function of DC-DC converters are investigated. The measured results are compared with TCAD MixedMode simulation.

The paper deals with investigation of radiation damage produced in 4H-SiC by different projectiles and its effect on power device characteristics.

The paper deals with the influence of neutron irradiation on electrical characteristics of 4H-SiC power devices.

This paper deals with an effect of radiation damage produced by fast neutrons on characteristics of JBS diodes produced on 4H-SiC, dynamic characterization methode for I-V measurement and SPICE model of neutron irradiated JBS diode.

This paper deals with the simulation and modeling of the effect of neutron irradiation on 4H-SiC 1700V normally-off JFET.

Fast recovery p-i-n diode with anode p-n junction modified by the radiation-enhanced diffusion (RED) of gold is presented. The RED of gold is shown to provide the local lifetime control of excess carriers, the compensation of n-base doping profile from n-type to p-type, and the enhancement of concentration of two gold-related deep levels. The deep level Au−/0 (EC − 0.549 eV) controls the low-level lifetime, whereas the gold–hydrogen pair (EC − 0.215 eV) the high-level lifetime. This feature eliminates the drawback of negative temperature coefficient of forward voltage drop of the RED with palladium and platinum, where only a single deep level, which controls the high-level lifetime, is enhanced. The RED of gold provides the maximal reverse bias safe operation area at the annealing temperature of 600 °C, whereas the RED of palladium at 650 °C.

4H silicon carbide Schottky diodes were irradiated by 550 keV protons with the aim to place the ion range into the low-doped n-type epitaxial layer. The diodes were characterized using DLTS, C–V profiling and forward I–V curves. Calibration procedure of model parameters for device simulation as been carried out. It is based on modeling the doping compensation of the n-type epitaxial layer caused by the deep acceptor levels resulting from radiation damage. It is shown that the agreement of simulated and measured forward I–V curves of proton irradiated diodes can be achieved, if the profiles of deep levels are calibrated with respect to irradiation dose, the degradation of electron mobility due to charged deep levels is accounted of and the Schottky barrier height is properly adjusted. The proposed methodology introduces a starting point for exact calibration of ion irradiated SiC unipolar devices.

This paper deals with effect of neutron irradiation on static and dynamic characteristics of high voltage 4H-SIC JFET

the paper deals with investigation of the point defects in 4H-SiC epilayers introduced by 4.5 MeV electron irradiation and their effects on power JBS SiC diode characteristics.

The paper deals with electronic properties of radiation damage produced in 4H-SiC by neutron irradiation and its effect on electrical parameters of Junction Barrier Schottky (JBS) diodes.

Electronic properties of radiation damage produced in 4H-SiC epilayer by proton and alpha particle irradiation were investigated and compared. 4H-SiC epilayers, which formed the low doped n-base of Schottky barrier power diodes, were irradiated to identical depth with 550 keV protons and 1.9 MeV alphas. Radiation defects were then characterized by capacitance deep-level transient spectroscopy and C-V measurements.

The effect of ion irradiation on electrical characteristics of SiC Schottky barrier power diodes was investigated. Diodes were irradiated from the anode side with 550 keV protons or 1.9 MeV alphas to place radiation defect maximum into the low doped epitaxial layer which formed the N-base of the diode. Radiation defects were then characterized by capacitance deep-level transient spectroscopy and their influence on diode static and dynamic characteristics was evaluated. Results show that low fluences of both proton and alpha particle irradiation have a negligible effect on dynamic and blocking characteristics of SiC power diodes. However, in contrast with silicon devices, the ON-state resistance of SiC diodes increases significantly already at very low fluences. This negative effect is given by high introduction rates of radiation defects in SiC due to the suppressed annihilation of primary damage.

High-power P-I-N diodes (2.5 kV, 150 A) with sputtered NiV and NiCr layers at anode were implanted by 10 MeV helium ions and subsequently annealed in the range 550 - 800 oC. The devices were characterized using XPS, DLTS and OCVD. Leakage current, forward voltage drop and reverse recovery measurements were measured as well. The Radiation Enhanced Diffusion (RED) of nickel was registered after 20 min. annealing between 675 and 725 oC. The evidence was provided by depth profiling (DLTS). The effect of the RED of nickel on device electrical parameters was evaluated. Contrary to the palladium, the RED of nickel is not sufficient for the local control of carrier lifetime in power devices.

Low-temperature diffusion of Cr, Mo, Ni, Pd, Pt, and V in silicon diodes is compared in the range 450 - 800 degC. The devices were characterized using AES, XPS, DLTS, OCVD carrier lifetime and diode electrical parameters. The metal atoms are divided into two groups. The Pt and Pd form deep levels in increased extent at the presence of radiation defects above 600 degC, which reduces the excess carrier lifetime. It is shown as a special case that the co-diffusion of Ni and V from a NiV surface layer results fully in the concentration enhancement of the V atoms. The enhancement of the acceptor level V-/0 (EC - 0.203 eV) and donor level V0/+ (EC - 0.442 eV) resembles the behavior of substitutional Pts. The second group is represented by the Mo and Cr. They easily form oxides, which can make their diffusion into a bulk more difficult or impossible. Only a slight enhancement of the Cr-related deep levels by the radiation defects has been found above 700 degC.

High-power P+P-N-N+ diodes (VRRM = 2.5 kV, IFAV = 150 A) with sputtered Mo layer at anode were annealed in the range 550-800 C with and without the presence of radiation defects from helium implantation (10 MeV, 1 1012 cm2). The devices were characterized using DLTS, spreading resistance, OCVD lifetime, leakage current, forward voltage drop and reverse recovery measurements. The diffusion of Mo from the 50 nm thick surface layer was not registered even after 4 h between 550 and 800 C in a rough vacuum.

High-power diodes with the radiation enhanced diffusion (RED) of Pd are shown to have much higher ruggedness during the reverse recovery compared to that of the Pt. Anode doping profiles measured by spreading resistance technique after a 10 MeV He implantation with subsequent annealing between 500 and 800 degC reveal different compensation effects between the Pd and Pt. The in-diffusing Pd converts the n-type background doping concentration of ND = 3 .1013 cm-3 in the position of radiation defects to that of a p-type with about one order higher concentration. The created low-doped p-layer significantly increases ruggedness of diodes during reverse recovery.

High-power P-I-N diodes (2.5 kV, 150 A) with sputtered Mo layer at anode were annealed in the range 550 - 800 oC with and without the previous 10 MeV helium implantation. The devices were characterized using DLTS, spreading resistance, OCVD lifetime, leakage current, forward voltage drop and reverse recovery measurements.

2.5 kV fast recovery diodes based on the Radiation Enhanced Diffusion of palladium and platinum are compared in electrical parameters in the application of fast swtching.

We investigate the influence of the higher production rate of the divacancy for the purpose of radiation enhanced diffusion (RED). We also compare the standard implantation of light (He) and heavy ions (Ne) to quantify the concrete impact on diode electrical parameters.

We introduce a fully functional high voltage and high current p+p-n-n+ diode based on Radiation Enhanced Diffusion (RED) technology. The diode was processed on a 100 mm wafer and can safely turn off 4 and 7 kA @ 140oC @ 1500 A/us for the diameters of 51 and 91 mm, resp. The RED diode has low leakage, excellent SOA capability under free-wheeling conditions, very good softness, and very high SOA with di/dt towards 10kA/us. Clamp-less operation is presented up to 1300 A with peak power above 15 MW at 125 oC for the 91 mm diodes.

P-i-N Diode with burried low doped P-layer and the impact of the Radiation Enhanced Diffusion from Sputtered Palladium on device parameters is explained in more details.

Radiation Enhanced Diffusion of Implanted Palladium in a High-Power P-i-N Diode is shown in the light of improved electrical parameters

Influence of anode contact on the forward voltage drop of a power diode.

Experimental and simulation work showing the impact of irradiation on device characteristocs in a wide temperature range.

Second extended issue

Helium irradiated high-power PIN diodes were characterized by the OCVD method for measurement of lifetime

The paper describes the basic aspects of PCB design, such as PC design, multilayer PCBs, SMD mounting and soldering, and electrical properties of printed circuit boards. The extensive part of the book is dedicated to electromagnetic compatibility (EMC) and related design rules. Although PCs are very efficient in designing PCBs, it does not mean that designing PCBs on a computer is simply clicking on the mouse. Computer design systems are only effective tools to make designers work easier. The design of the PCB requires, in particular (although it does not look like it at first glance) complex knowledge in the areas of: PCB manufacturing, assembly and soldering, peripheral function of components, electromagnetic field theory and above all their articulation and use in practice. The aim of the book is to draw readers to the most important issues they will have to deal with when designing electronic circuit boards and printed circuit boards. The designer will not only become a reader of publications, but will be actively involved in long-term work, collecting experience and feedback from the entire manufacturing process of the proposed equipment, from PCB and assembly processors, from EMC testing laboratories, service technicians and others. In practice, this means not only "learning, learning, learning," but also "communicating, communicating, communicating", accepting criticism and learning not only from own mistakes. less text

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