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Despite the extensively researched physical principles, numerous published simulations on SiC drift step recovery diodes (SiC DSRD) and the practical implementation of SiC DSRD-based pulses, there are few kinds of research focusing on collaborative design between a SiC DSRD and its driving circuit. In this paper, a collaborative design method of a SiC DSRD and its driving circuit are presented. In addition, a detailed simulation is conducted to verify design considerations and to analyze the impact of driving parameter changes on the output pulse waveform. A pulse generator prototype with a self-developed SiC DSRD is implemented. The experimental results show that the circuit can output a peak voltage of 790 V on a matching load of 50 Ω, with a rise time of 520 ps (20%~80%), and can work at a 1 MHz repetition frequency rate with good stability. [ABSTRACT FROM AUTHOR]

Silicon Carbide (SiC) Ultraviolet (UV) phototransistors with bidirectional bias response were fabricated and analyzed in this letter. The results showed that the fabricated UV phototransistor exhibited stable photoelectric response characteristics and transistor characteristics under both forward and reverse voltages, owing to the structure design of the epi-layers, while the mechanism of the bidirectional response was also studied. The difference in photocurrent under different bias voltages and wavelengths of UV illumination were mainly due to the variation of the absorption coefficient with wavelength and the change in the width of the space charge regions, which ultimately led to a difference in the number of photo-generated carriers. The time response characteristics of the detector showed that there were time delays when the detector was turned on and turned off, which was caused by the photo minority carriers in the depletion layer of the base-collector junction. [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]

A new structure of a 4H‐SiC bipolar transistor with ultra‐high current gain is proposed and analysed by simulation. A p‐type Schottky contact serving as the conventional emitter region is introduced. By proper choice of the metal work‐function, the injection efficiency of the minority carrier (electron) is promoted and may be close to unity. Therefore high current gain is realised due to the high electron current density injected from the p‐type Schottky contact. The simulation results show that the current gain varies with the metal work‐function and could reach ∼1000, which is attractive for the base‐drive circuit. Moreover, the new structure simplifies the etching process compared with the conventional bipolar junction transistor. [ABSTRACT FROM AUTHOR]

The properties of 4H–SiC/Ni/Ti/Al/W metal contacts on n-type and p-type ion-implanted 4H–SiC layers are studied in this paper, with the aim of realizing simultaneous ohmic contact formation. The thickness of the Al film and the alloying temperature are analyzed. Specific contact resistances of 8 × 10−4 Ω cm2 and 4.1 × 10−5 Ω cm2 were achieved with multi-metal layer Ni/Ti/Al/W (80/30/110/50 nm) for n-type and p-type 4H–SiC, respectively, at an annealing temperature of 750 °C. This is for first time at such a low annealing temperature that ohmic contacts have been reported to simultaneously form on n-type and p-type 4H–SiC with satisfactory specific contact resistances. Samples were characterized using AFM, XRD, AES and TEM, and the results indicate that the presence of the W top layer facilitates lowering the surface roughness and accumulating elemental Ni and Al on the SiC side during annealing, which benefits the formation of the ohmic contacts. • Ni/Ti/Al/W on n-type and p-type 4H–SiC with various Al layer thicknesses are studied. • Ohmic contacts have been simultaneously formed on n-type and p-type 4H–SiC at 750 °C. • It's for the first time at such a low annealing temperature ohmic contacts have been formed. •The top layer W metal results in the formation of Ni2Si and Al-Rich at the interface. [ABSTRACT FROM AUTHOR]