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In this article, the breakdown voltage (${V}_{\text {BR}}$) shift of 4H-SiC Junction Barrier Schottky (JBS) diodes terminated by optimum nonequidistant field limiting rings (FLRs) subject to reverse-bias stress (RBS) has been investigated, and the corresponding mechanisms are studied in-depth. It can be observed that ${V}_{\text {BR}}$ gradually increases with increasing stress time, but there is no obvious shift of the forward voltage (${V}_{F}$). The increment in the magnitude of ${V}_{\text {BR}}$ induced by RBS testing is shown to depend strongly on the degree of applied reverse-bias voltage. The physical mechanism of ${V}_{\text {BR}}$ shift has been investigated and explained by means of numerical technical computer-aided design (T-CAD) simulations. Our analysis shows that the hole injection and trapping into SiO2 at the FLR terminal area are identified to be the main cause, resulting in the increase of ${V}_{\text {BR}}$. Besides, a simple model is proposed to explain the behavior of ${V}_{\text {BR}}$ instability. [ABSTRACT FROM AUTHOR]

High-temperature storage stressing (HTSS) experiments were carried out on high-voltage 4H-SiC junction barrier Schottky (JBS) diodes. The effects of the high-temperature (up to 275 °C) storage under air environment on thermal stability of the 4H-SiC JBS are investigated. The electrical parameter shifts for tested diodes after the HTSS were investigated in detail, and related degradation mechanisms have been discussed. It is found that HTSS has no effect on the Schottky barrier height, the ideality factor (n), and specific on-resistance ( $R_{{\text{on-sp}}}$). However, it was interesting that the breakdown voltage ($V_{{\text{BR}}}$ ) of the devices was decreased first and then increased as the storage time increased. With the analysis of the SiO2/4H-SiC interface characteristics using metal-oxide-semiconductor structure fabricated simultaneously with the investigated 4H-SiC JBS on the same wafer and technical computer-aided design (T-CAD) simulations, trapped-electrons and holes located at the interface of SiO2/4H-SiC on termination region are identified to be the basic reason causing the degradation of reverse characteristics in the devices. [ABSTRACT FROM AUTHOR]

In this paper, a novel 4H SiC trench metal-oxide-semiconductor field-effect transistor (MOSFET) with non-uniform doping floating islands is proposed, using a Gaussian doping profile in the floating islands. The feature of the non-uniform doping floating island is that the doping concentration of upper part is higher than the lower part. The electric field between the floating island and drift region can be reduced by the decrease in the doping concentration of the lower part. At the same time, the high doping concentration for the upper part of the floating island is utilized, so that gate oxide layer at the sharp corner of the trench gate bottom cannot be broken down in advance. The simulation results indicate that the breakdown voltage of the novel structure can increase by 48%, compared with the structure with the uniform doping (6 × 10 17 cm −3 ) floating island. Furthermore, the switching and gate charge characteristics of the UMOSFETs with uniform and Gaussian doping floating islands have been simulated using two simple switching circuits. The results indicate that changing the doping concentration of the floating islands has no negative effect on the switching characteristics. [ABSTRACT FROM AUTHOR]

In this paper, a 4H-SiC Junction Barrier Schottky diode (JBS) with non-uniform floating limiting rings (FLRs) has been investigated and fabricated using n type 4H-SiC epitaxial layer with thickness of 31 μm and doping concentration of 3.3 × 10 15 cm −3 . According to the simulated results, the key parameters of a FLRs design to achieve a high voltage are the minimum space between two adjacent doped rings, spacing growth step and number of rings. The experimental results also show a great agreement with simulated results. Meanwhile, a near-ideal breakdown voltage of 3.7 kV was achieved, which yield around 95% of the parallel-plane breakdown voltage. The forward characteristics show that the fabricated JBS diodes have a forward current density of 210 A/cm 2 at 3 V and a specific on-resistance ( R sp-on ) of 7.58 mΩ cm 2 . Different FLRs parameters have no effect on the forward device performance. [ABSTRACT FROM AUTHOR]