Papers by Keyword: PiN Diode

Abstract: SiC GTOs, with high current handling capability, are promising for high-voltage and high-power applications, but they also have temperature-related reliability issues, so real-time junction temperature monitoring is needed. In this paper, a novel 4H-SiC gate turn-off thyristor (GTO) structure with integrated temperature sensor is proposed. The proposed sensor is compatible with the SiC GTO process and allows for real-time temperature monitoring. TCAD simulation results show that the integrated sensor has a high sensitivity of 1.64mV/K and linearity of 0.99891, the temperature sensor monitors the internal temperature of the GTO device in real time with an error of no more than 2 K during complete GTO switching. This new structure is conducive to enhancing the reliability of SiC thyristor applications and system miniaturization.

Abstract: Low gain avalanche detectors (LGADs) offer high temporal resolution for high energy particle detection, which is critical for next generation experiments in hadron colliders. While silicon LGADs (Si-LGADs) have rapidly matured in the last decade, research into silicon carbide (SiC) LGADs has only recently begun. By accounting for fundamental differences in material properties and fabrication processes, we present a prototype device design and process flow for 4H-SiC LGADs with etch-based isolation. Critical steps of the process flow and their results are discussed, including plasma etching, passivation, and the formation of low resistivity contacts. Electrical characterization (I-V, C-V) shows sufficient depletion of the device structure to demonstrate low-gain charge carrier multiplication.

Abstract: 4H silicon carbide (SiC) based pin photodiodes with a sensitivity in the vacuum ultraviolet spectrum (VUV) demand newly developed emitter doping profiles. This work features the first ever reported 4H-SiC pin photodiodes with an implanted p-emitter and a noticeable sensitivity at a wavelength of 200 nm. As a first step, Aluminum doping profiles produced by low energy ion implantation in 4H-SiC were characterized by secondary-ion mass spectrometry (SIMS). Photodiodes using these shallow emitters are compared to one with a deep p-emitter doping profile employing IV characteristics and the spectral response. SIMS results demonstrate the possibility of shallow Alimplantation profiles using low implantation energies with all emitter profiles featuring characteristic I-V results. For some shallow doping profiles, a meassurable signal at the upper limit of the VUV spectrum could be demonstrated, paving the way towards 4H-SiC pin photodiodes with sensitivities for wavelengths below 200 nm.

Abstract: 6.5 kV SiC PiN diode with JTE and p+ rings termination was fabricated and characterized. The static and dynamic performance of SiC PiN diode were compared with that of SiC JBS diode and silicon diode, while switched in combination with a silicon IGBT. SiC PiN provides clear advantage while operating at higher current densities (above 100 A/cm²) and had lower leakage current. When switched together with a silicon IGBT, they contribute to losses similar to that of a SiC JBS diode.

Abstract: This work aims at extending the predictive simulation technique for cosmic ray-induced failure analysis from Si PiN diodes [1] to SiC PiN diodes. Accurate 3D cylindrical-symmetric transient simulations were performed with a minimum mesh size of 20nm at the center track of the impinging ion and a maximum time step of 0.1ps during the development of the ion-induced transient current. We made a comparative study between a SiC PiN diode and a Si PiN diode with the same blocking voltage of 1.5kV, using the same heavy ion transportation models. In the simulation, we observed different ion-induced current transients, differing not only in the peak value of the current, but also in its duration. Due to different physical mechanisms, the dependence of the ion-induced current on the reverse pre-bias voltage and the numerical mesh adaptations are also different. Eventually, we brieflydiscuss electro-thermal simulations, which indicate once more that the ion-induced transient current in the SiC PiN diodes under consideration is primarily drift current and involves only negligible impact ionization.

Abstract: Expansion of single Shockley stacking faults (SSFs) during forward current operation is an important issue, because it decreases the reliability of 4H-SiC bipolar devices. In this paper, we propose a method for analyzing SSF dynamics based on free energy under current conduction, temperature, and resolved shear stress conditions. The driving force for dislocation dissociation reactions and formation of SSFs is incorporated into the free energy function, including chemical potential, stacking fault energy, crystallographic energy, gradient energy and elastic strain energy. The net energy gain of the chemical potential was calculated as a function of temperature and current conduction through use of the a TCAD device simulator based on the Boltzmann equation, Poisson equation and the current continuity equation concerning electron and hole distributions with self-consistency. It was confirmed that SSF dynamics can be simulated by the proposed method. It was also found that SSF formation can be attributed to quantum well variation in which electrons in n-type 4H–SiC enter SSF-induced quantum well states to lower the energy of the dislocation system.

Abstract: In this paper, the application of a high temperature thermal oxidation and annealing process to 4H-SiC PiN diodes with 35 μm thick drift regions is explored, the aim of which was to increase the carrier lifetime in the 4H-SiC. Diodes were fabricated using 4H-SiC material and underwent a thermal oxidation in dry pure O₂ at 1550^◦C followed by an argon anneal at the same temperature. Reverse recovery tests indicated a carrier lifetime increase of around 42% which is due to increase of excessive minority carriers in the drift region. The switching results illustrate that the use of this process is a highly effective and efficient way of enhancing the electrical characteristics of high voltage 4H-SiC bipolar devices.

Abstract: This study investigated the relationship between the forward voltage degradation induced by SSF expansion and (a) BPD density in substrates and epitaxial layers of SiC, and (b) the temperature during the application forward current to the pin diodes. The V_f shift caused by the BPDs in the drift layer simply depended on the BPD density. However, no correlation was initially observed between the V_f shift and BPD density in the substrate; instead a strong correlation was observed between the V_f shift and the device temperature measured when applying the current stress. Thus when we selected samples which show the same temperature at that time, a correlation was observed between the V_f shift and the BPD density in the SiC substrate, with the slope corresponding to the former, drift layer relationship. Therefore, due to the high BPD density in the SiC substrate, suppressing the V_f shift due to BPD density in this region is highly important, and a combination of approaches is therefore proposed in order to reduce the overall forward voltage degradation.

Abstract: An in-house fabricated 4H-SiC PIN diode that has both optical sensing and temperature sensing functions from room temperature (RT) to 550 °C is presented. The two sensing functions can be simply converted from one to the other by switching the bias voltage on the diode. The optical responsivity of the diode at 365 nm is 31.8 mA/W at 550 °C. The temperature sensitivity of the diode is 2.7 mV/°C at the forward current of 1 μA.

Abstract: Implantation-free mesa etched 10+ kV 4H-SiC PiN diodes are fabricated, measured and analyzed by device simulation. An area-optimized junction termination extension (O-JTE) is implemented in order to achieve a high breakdown voltage. The diodes design allows a high breakdown voltage of about 19.3 kV according to simulations by Sentaurus TCAD. No breakdown voltage is recorded up to 10 kV with a very low leakage current of 0.1 μA. The current spreading within the thick drift layer is considered and a voltage drop (V_F) of 8.3 V and 11.4 V are measured at 50 A/cm² and 100 A/cm², respectively. The differential on-resistance (Diff. R_on) of 67.7 mΩ.cm² and 55.7 mΩ.cm² are measured at 50 A/cm² and 100 A/cm², respectively.