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In this paper, Pt/TaSi 2 /Ni/Ti/Ni/SiC and Pt/Ti/SiC simultaneous ohmic contacts to n-type and p-type 4H-SiC are studied. The thermal stability and electrical characteristics of the ohmic contacts are investigated and compared after being aged at 500 °C for 300 h in air. The n- and p-type Pt/Ti/SiC ohmic contact failed after 100 h and after 200 h, respectively. While the Pt/TaSi 2 /Ni/Ti/Ni/SiC samples exhibits a good thermal stability and high temperature electrical characteristics, with a relatively small increase of the specific contact resistance (SCR) in the initial 50 h and then remains stable in the rest of the thermal aging duration. SEM analysis reveals that the surface morphologies of Pt/TaSi 2 /Ni/Ti/Ni/SiC samples keep smooth and stable during the aging process. According to AES analysis, the main reason of electrical characteristics degradation is the oxidation on the metal/4H-SiC interface during the aging process. Also, at the expense of the TaSi 2 layer oxidization, the diffusion rate of oxygen atoms towards the SiC are slowed down, and therefore, the metal/4H-SiC interface quality was not affected by oxidation problems and extending the life of ohmic contact in air at 500 °C. Experimental results indicate that the Pt/TaSi 2 /Ni/Ti/Ni/SiC simultaneous ohmic contacts to both n- and p-type SiC are promising to be used for high temperature and harsh environment SiC-based devices. [ABSTRACT FROM AUTHOR]

The 4H‐SiC/SiO2 interface quality can be significantly improved by adding an alkaline earth metal interface layer. To study the passivation mechanism of the alkaline earth metal barium (Ba), a supercell model with a transition layer is established. As shown in the results from first‐principles calculations, the bandgap increases and the density of states decreases when SiBaO or OBaO structures are introduced into the transition layer. 4H‐SiC/Ba interface layer/SiO2 capacitors with different annealing conditions are fabricated. X‐ray photoelectron spectroscopy results show that Ba mainly exists in the form of BaO2 (corresponding to the OBaO structure) after annealing in 5% O2 in Ar atmosphere, and there are fewer types of suboxides in the interface than those annealed in Ar. A small amount of Ba also combines with SiO2 to form SiBaxOy compounds (corresponding to the SiBaO structure). The correctness of the theoretical analysis is verified by capacitance–voltage measurements. The physical mechanism of Ba passivation is analyzed in this article, which helps to improve the performance of SiC metal–oxide–semiconductor (MOS) structure devices. [ABSTRACT FROM AUTHOR]

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]

SiC is a promising material for neutron detection in a harsh environment due to its wide band gap, high displacement threshold energy and high thermal conductivity. To increase the detection efficiency of SiC, a converter such as 6 LiF or 10 B is introduced. In this paper, pulse-height spectra of a PIN diode with a 6 LiF conversion layer exposed to thermal neutrons (0.026 eV) are calculated using TCAD and Monte Carlo simulations. First, the conversion efficiency of a thermal neutron with respect to the thickness of 6 LiF was calculated by using a FLUKA code, and a maximal efficiency of approximately 5% was achieved. Next, the energy distributions of both 3 H and α induced by the 6 LiF reaction according to different ranges of emission angle are analyzed. Subsequently, transient pulses generated by the bombardment of single 3 H or α -particles are calculated. Finally, pulse height spectra are obtained with a detector efficiency of 4.53%. Comparisons of the simulated result with the experimental data are also presented, and the calculated spectrum shows an acceptable similarity to the experimental data. This work would be useful for radiation-sensing applications, especially for SiC detector design. [ABSTRACT FROM AUTHOR]