Papers by Keyword: SBD

Abstract: Silicon carbide (SiC) Schottky barrier diodes (SBDs) have become critical components in power electronics due to their excellent high-voltage, high-temperature tolerance, and fast switching capability. However, increasing device area to improve current-carrying capability increases the total number of defects, which leads to an increase in reverse leakage current and reduces wafer yield. To improve current distribution uniformity within SiC module packaging, reduce system size and weight, and enhance the current-carrying capacity and high-temperature stability of a single SBD, this paper develops 750V/100A and 1200V/100A SiC SBDs on 6-inch wafers. For the 750V/100A device, the corresponding forward voltage (V_F) at forward current (I_F) of 100 A is 1.68 V. For the 1200V/100A device, the corresponding V_F is 1.75V. Calculation based on the current voltage characteristics shows that the ideal factors of 750V/100A and 1200V/100A devices are 1.01 and 1.04, respectively, which are very close to 1. It demonstrates excellent Schottky contact and a high-quality interface. The devices exhibit high-temperature stability, meeting the demands of high-temperature applications.

Abstract: This paper investigates the effect of DLTS measurement parameters on characterizing deep level defects in 4H-SiC Schottky barrier diode (SBD). By adjusting parameters such as the time window (t_W), pulse time (t_P), reverse voltage (U_R), and pulse voltage (U_P), the underlying mechanisms influencing defect peak positions, signal amplitudes, and peak broadening are analyzed. Experimental results reveal three deep level defects identified in 4H-SiC SBD: majority carrier traps T1 (E_C - 0.66 eV) and T2 (E_C - 1.0 eV), along with minority carrier trap T3 (E_V + 1.1 eV). Parameter settings not only influence defect characterization sensitivity and concentration calculations but also reveal the dynamics of carrier capture and emission. Through the thorough analysis of the DLTS signal and behavior under different DLTS measurement conditions, the electronic properties and concentration profiles of deep level defects in 4H-SiC epitaxial layers are determined.

Abstract: The influence of the recovery characteristics on the switching behavior of SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) with different switching speeds was investigated. A comparative analysis of the devices with different recovery characteristics revealed an increase in the turn-on loss (E_on) owing to the higher output capacitance charge (Q_oss) and reverse recovery charge (Q_rr) in the recovery arm. On the other hand, a higher Q_oss in the recovery arm resulted in a lower turn-off loss (E_off). In addition, an increase in Q_oss and Q_rr further influenced E_on and E_off at a higher switching speed. Furthermore, a higher Q_rr observed at a higher switching speed indicated a more significant impact of Q_rr on E_on at a high switching speed than that of Q_oss. The findings clarified in this study highlight the necessity of focusing the recovery characteristics to ensure a desirable switching loss of SiC MOSFETs.

Abstract: The diffusion welding (DW), known as direct bonding technique could be more used as an alternative approach to develop silicon carbide (SiC) Schottky rectifiers to existing mainstream metallization contact technologies. Measured results for p-type 4H-SiC Schottky barrier diodes (SBD) arepresented. And comprehensive numerical study to characterize the device has been performed. The simulations are carried out with ATLAS software (Silvaco). The measured and numerically simulated forward current-voltage (I–V) and capacitance-voltage (C–V) characteristics in a large temperaturerange are analyzed. Some of the measured p-type 4H-SiC Schottky diodes show deviation in specific ranges of their electrical characteristics. This deviation, especially due to excess current, dominates at low voltages (less than 1 V) and temperatures (less than room temperature). To verify the existence of electrically active defects under the Schottky contact, which influences the Schottky barrier height (SBH) and its inhomogeneity, the deep level transient spectroscopy (DLTS) technology was applied. DLTS measurements show the presence of a deep-level defect with activation energy corresponding typically for multilevel trap clusters.

Abstract: A total loss reduction of 3.3 kV power module by using SiC-MOSFET embedding SBD has been demonstrated through the investigation of DC characteristics and switching characteristics. Despite 1.1 times larger on-resistance than that of conventional SiC-MOSFET due to larger cell pitch, superior switching characteristics of SiC-MOSFET embedding SBD, which are due to smaller total chip area than that of SiC-MOSFET coupled with external SBD and due to elimination of recovery charge by minority carrier injection compared with SiC-MOSFET utilizing its body diode, enable the total loss reduction especially for high frequency operation.

Abstract: Silicon Carbide JBS diodes are capable, in forward bias, of carrying surge current of magnitude significantly higher than their rated current, for short periods. In this work, we examine the mechanisms of device failure due to excess surge current by analyzing variation of failure current with device current and voltage ratings, as well as duration of current surge. Physical failure analysis is carried out to correlate to electrical failure signature. We also quantify the impact, on surge current capability, of the resistance of the anode ohmic contact to the p-shielding region.

Abstract: The dislocation of a p⁺ high-temperature, high-pressure (HPHT) seed crystal is analyzed by X-ray topography using a SR light source, and compared with that of an insulating HPHT seed crystal. The dislocation density of the typical insulating HPHT substrate is around 250 cm^-2. Over several years, significant progress has been achieved in reducing the dislocation density of the typical insulating HPHT substrate from the order of 10⁴–10⁵ cm^-2 to 10² cm^-2. The p⁺ HPHT seed crystal has unique properties, especially in terms of the number of stacking faults (SFs), and very clear growth sector boundaries with dislocation densities of up to 3000 cm^-2. As most research activities have been focused on the “insulating substrate” in HPHT growth technology for a long time, several challenges need to be overcome with respect to the growth of a p⁺ HPHT crystal.

Abstract: Characteristics of SiC MOSFETs and SBDs with 3.3 kV-class have been presented. Static Characteristics of the MOSFET showed a specific on-resistance of 14.2 mΩ cm². A breakdown voltage of 3850 V is obtained by using the dose optimized edge termination structure as we have previously reported [1]. At the same time, reverse leakage current of the 3.3 kV SiC SBDs can be suppressed by the JBS structure and the edge termination which is also used in the MOSFETs. By using the MOSFETs and SBDs, we have demonstrated the superior capability of the 3.3 kV 400 A full SiC 2 in 1 modules with a compatible case and terminal configurations to Si IGBT modules. Dynamic characteristics of the full SiC module in an inductive load switching exhibits superior turn-on and turn-off properties even at a high drain voltage of 1650 V, demonstrating the availability of high voltage SiC power systems.

Abstract: In this paper, semiconductor simulation software ISE TCAD 10.0 was used to simulate W/SiC SBD forward voltage characteristics and reverse voltage characteristics at different temperatures on the basis of theoretical analysis, and the valuable results were achieved. Under the temperature range from 73 K to 773 K, the simulation results of W/SiC Schottky barrier diode forward voltage characteristics showed that forward characteristics were significant influenced by the temperature. At room temperature (303K), if bias voltage was low, the current will be exponential growing with voltage, and the turn-on voltage of W/SiC Schottky barrier diode was about 0.2V. If bias voltage was high, the current increased will be high, and the series resistance effect will become obvious. Under lower bias (2V), a different temperature from 73K to 573K had small impact on reverse current-voltage characteristics. The results showed that the device had the good rectifier characteristics, small reverse current, high breakdown voltage, and the device can steadily and long-term work in high temperature and other complex environment.

Abstract: In this paper, we demonstrate the fabrication of SBD utilizing SiC process line specially designed for mass production of SiC power device. In SiC power device process, ion implantation and activation annealing are key technologies. Details of ion implantation system and activation annealing system designed for SiC power device production are shown. Further, device characteristics of SBD fabricated using this production line is also shown briefly.