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In this study we analyzed the physical mechanisms governing time-dependent dielectric breakdown (TDDB) and we used TDDB physical model of dielectric breakdown, implemented in the defect-centric Ginestra® modeling platform, to deconvolute the intrinsic material properties effects and geometry feature impact on the gate oxide (GOx) and SiC-device breakdown.

A numerical model is presented for the simulation of ultraviolet ion-implanted 4H-SiC photodiodes with shallow p- emitter doping profiles. An existing model for SiC pin photodiodes, taken from literature, is modified with a dedicated SiO2-SiC interface layer to account for degradation of carrier mobility and lifetime at the interface. Furthermore, aluminum compensation in 4H-SiC is included and its impact on the spectral response and carrier recombination is analyzed. The simulated spectral response in the wavelength range from 200 to 400 nm is compared to experimental data. While the existing model, taken from literature, fails to predict the performance of VUV photodiodes with a shallow p- emitter, the newly designed model successfully achieves high accuracy, even with a basic modeling approach featuring an abrupt material parameter transition.

In this work, an analytical model describing the quasi-static operation of a monolithically integrated SiC solid-state circuit breaker (SSCB) device is rederived and refined. This SSCB is based on a 4H-SiC JFET technology offering a self-sensed blocking mechanism. The proposed model is solely based on physical parameters including the SSCB design parameters. With respect to the refinement, the proposed model is not limited to one-sided pn-junctions, considers incomplete ionization of dopants, and is able to represent breakdown characteristics. In this regard, the JFET gate breakdown characteristics are derived taking thermionic emission, space-charge-limited current and impact ionization into account. To calculate the SSCB output characteristics, a bisection-based optimization algorithm is applied carefully considering individual JFET operating states.

This work presents the results of process development for trench formation in SiC power devices to increase the trench depth by improving SiC/SiO2-selectivity of the dry etch process. Motivation behind this development is to further improve the electrical properties of conventional devices like SiC MOSFETs by implementing a trench geometry, allowing the cell pitch to be increased, leading to a reduced on-resistance of SiC TrenchMOS devices. Trench etching was performed on 4H-SiC substrates by utilizing an oxide hard mask, patterned by photolithography and dry etching. The SiC trench profile was analyzed by cross-section preparation via FIB and SEM imaging. The highest SiC/SiO2-selectivity achieved was 7.9, with SiF4 gas flow being the most decisive parameter for it. With that, the selectivity of the standard SiC trench etch process was increased by nearly five times. SiC trenches with depths of 5 µm could be demonstrated. However, then the structural fidelity was deteriorated, with micro-trenching and sidewall bowing being the largest limitations regarding applicable trench depth in SiC power devices.

The living anionic copolymerization of isoprene (I) and styrene (S) can afford a variety of different polymer microstructures that strongly depend on experimental parameters such as solvent, counterion, and temperature. In this work, in situnear-infrared (NIR) spectroscopy was employed as a versatile and fast method to track the conversion of the individual monomers in a nonpolar (cyclohexane, CyH) and a coordinative solvent mixture (CyH with 1.5%voltetrahydrofuran (THF)). For the first time, in situmonitoring of the copolymerization is performed by deriving the individual monomer signals from the superimposed spectra using the molar attenuation coefficients of each component in the wavenumber range of 5900–6250 cm–1. The polymerization in nonpolar solvents features a unique kinetic behavior and is known to result in tapered block copolymers. Kinetic rate constants and the corresponding activation energies were determined in CyH, covering a broad temperature range of 10–60 °C. Paralleling the experimental studies, the polymerization was also simulated in silicoby feeding the measured kinetic rate constants into a kinetic Monte Carlo simulation (kMC). This combination of in situmonitoring and kMC simulation allows to reduce reaction times, which is especially desired in multiblock syntheses. The observed differences in activation energies aid in understanding the temperature dependence of the reactivity ratios. Thus, temperature can be used as an external parameter to adjust the gradient and the size of the polystyrene block. The peculiar temperature dependence of the gradient affects the resulting bulk morphology. This led to a surprising partial change from the lamellar to the tetragonally cylindrical or perforated lamellar structure at the identical isoprene/styrene composition, only caused by a change of the polymerization temperature. In situNIR probing is established as a fast and accurate method for real-time copolymerization monitoring that enables tracking complex copolymerization procedures, such as multiblock formation with a temporal resolution exceeding current standards set by 1H NMR kinetics.