SiC vs Silicon Schottky: What Four Switching Waveforms Can Tell You

Last Updated: 2026-10-06

Quick Answer

SiC and silicon Schottky diodes both use majority-carrier conduction, so a silicon PN recovery waveform is not a fair substitute for a silicon Schottky comparison. Inspect diode current, diode reverse voltage, switch current and switch voltage under matched conditions. These traces reveal commutation behavior, but they do not establish a universal technology winner.

SiC Schottky devices are valuable candidates for high-voltage rectification, while silicon Schottky devices remain useful in many lower-voltage circuits. The practical question is which exact device fits the voltage, temperature and loss requirements. Four synchronized measurements make that comparison more useful than a headline claim about recovery time.

A capacitive reverse pulse is not the same mechanism as PN stored-charge recovery.

Waveform 1: Diode Current

Define positive current as forward conduction. During forced turn-off, the current falls and a reverse-direction transient may appear while the junction capacitance changes voltage. The absence of minority-carrier storage does not imply a perfectly flat zero-current trace immediately after conduction ends.

Infineon’s Schottky switching explanation distinguishes capacitive charge from reverse recovery charge associated with stored carriers. Keep that distinction when interpreting a measured pulse. For a voltage-dependent capacitance, transferred capacitive charge is obtained by integrating capacitance over the voltage excursion, not by assuming one fixed capacitance at every voltage.

The four diagrams here are conceptual traces of a hard-switched commutation event. They show which features to inspect, without numerical scales or overlaid product measurements. A smaller pulse or shorter interval cannot be assigned to either technology without device-specific evidence.

Both comparison candidates must remain within their blocking ratings.

Waveform 2: Diode Reverse Voltage

Plot reverse-voltage magnitude as cathode voltage minus anode voltage. In forward conduction this quantity is slightly negative; after commutation it becomes positive. Inspect the plateau, overshoot and any ringing against the chosen device’s limits and design margin.

Use compatible candidates at the same applied voltage. Comparing a 200 V silicon Schottky and a 1200 V SiC device by applying 800 V to both is not a valid experiment. The lower-rated device is outside its blocking capability. If the candidates serve different voltage classes, describe that as an application-fit comparison rather than matched switching performance.

The transient can include capacitance and parasitic effects from the whole switching cell.

Waveform 3: Active-Switch Current

In a representative hard-switched boost or freewheeling commutation cell, the incoming switch takes over the load-related current. The transient peak can include current associated with charging and discharging capacitances as well as circuit parasitics. Identify the topology before assigning every extra ampere to the diode.

Measure the current before, during and after the transition. Compare peak stress and ringing at the same load, temperature and gate-drive settings. A changed diode capacitance can alter switch behavior even when neither candidate has the stored-charge recovery of a conventional PN rectifier.

Switching energy requires the time integral of measured voltage multiplied by measured current.

Waveform 4: Active-Switch Voltage

Capture switch voltage on the same time base as switch current. Turn-on energy is the integral of instantaneous switch voltage multiplied by switch current over a defined event window. Peak current alone does not supply that energy, and voltage-current probe delay can distort the integral.

The diagram shows voltage falling as the switch turns on; its shape is illustrative rather than a numerical match to a particular product. In a real comparison, use synchronized measured traces, consistent integration limits and corrected probe timing. Then include conduction and reverse-blocking losses when assessing total converter dissipation.

DSC40120P original model image: two-lead TO-247AC SiC Schottky device.

Anchor the Comparison to a Real Device

POWERSi DSC40120P is a 1200 V SiC Schottky example in a two-lead TO-247AC package. Its electrical table gives typical capacitive charge QC of 204 nC at Tj = 25°C and VR = 800 V. A nonzero charge entry is consistent with a capacitive commutation current; it is not evidence of PN-style stored-charge recovery.

At IF = 40 A, its table gives typical VF of 1.40 V at Tj = 25°C and 2.15 V at Tj = 175°C, with maxima of 1.53 V and 2.36 V respectively. These conditions matter when estimating conduction loss. Do not assume that a SiC option has the lowest forward drop at every load or temperature.

Key Takeaways

• Compare silicon Schottky with SiC Schottky, not with an unrelated PN trace.
• Separate capacitive current from stored-charge recovery.
• Keep both candidates within their voltage ratings.
• Combine synchronized switching measurements with hot conduction and blocking losses.

Conclusion

Four traces help identify where a proposed change affects stress and loss. When evaluating POWERSi SiC and rectifier products, state the voltage class and measured operating point first; the suitable technology follows from those requirements.

FAQs

Does silicon Schottky have conventional PN reverse recovery?

Its normal majority-carrier operation does not have the same stored-charge recovery mechanism, although capacitive current remains.

Does SiC mean zero switching charge?

No. Junction capacitance still transfers charge during a voltage transition.

Can a current spike alone determine switching energy?

No. Energy requires voltage and current over a defined time interval with correct timing alignment.

Should a 200 V and 1200 V device be tested at 800 V together?

No. The 200 V candidate would exceed its blocking rating, invalidating the comparison.

Is SiC always the lower-loss choice?

No. The outcome depends on voltage class, current, temperature, switching conditions and the exact devices.