3rd generation SiC MOSFETs that contributes to lower loss of power supply in application

Power devices are essential components for managing and reducing power consumption in all kinds of electronic equipment, and for achieving a carbon neutral society. SiC is widely seen as the next generation material for power devices, as it delivers higher voltages and lower losses than silicon. While SiC power devices are now mainly utilized in inverters for trains, wider application is on the horizon, in vehicle electrification and the miniaturization of industrial equipment. However, the adoption and market growth of SiC devices have been held back by reliability issues.

Therefore, our 3rd generation SiC MOSFETs have the following features.

  1. Built-in Schottky barrier diode (SBD) reduced the forward voltage VDSF , and suppresses fluctuation in on-resistance RDS(ON)
  2. The performance index RDS(ON) × Qgd, which shows the relation between conduction loss and switching loss, is reduced
  3. Wide gate-source voltage VGSS specification range

Toshiba's 3rd generation SiC MOSFETs have a lineup of 650 V and 1200 V voltage products and provides lower loss of power supply for applications such as servers, uninterruptible power supplies (UPS), Photovoltaics Inverter.

The features of our 3rd generation SiC MOSFETs are introduced in detail below.

Features of the 3rd Generation SiC MOSFETs

1. Built-in Schottky barrier diode (SBD) reduces VDSF and suppresses fluctuation in on-resistance RDS(ON)

Our 3rd-generation SiC MOSFET has a built-in Schottky barrier diode (SBD) in parallel with the PN diode that exists between the drain and source, so built-in Schottky barrier diode reduces the forward voltage VDSF during reverse conduction to 1.35 V (typ.).
By energizing the SBD, we suppress fluctuation of the on-resistance RDS(ON) between the drain and source caused by the spread of defects in the SiC crystal.
When a current density of 250 A/cm2 was applied from the source to the drain for 1000 hours, the on-resistance RDS(ON) of the SiC MOSFET without the built-in SBD was 42 % at maximum because the body diode was energized.
On the other hand, in the 3rd generation SiC MOSFETs with built-in SBD, we were able to suppress the fluctuation of on-resistance RDS(ON) to a maximum of 3 % because the SBD can be energized. 

Built-in Schottky barrier diode (SBD) reduces VDSF and suppresses fluctuation in on-resistance R<sub>DS(ON)</sub>

2. Reduced the conduction loss and switching loss performance index : RDS(ON) × Qgd

For our 3rd-generation SiC MOSFETs, the performance index RDS(ON) × Qgd, which shows the relation between conduction loss and switching loss, is reduced by 80 % [note] compared with our existing 2nd-generation products by optimizing its cell structure.

Reduced the conduction loss and switching loss performance index : R<sub>DS(ON)</sub> x Q<sub>gd</sub>

 

Measurement conditions
RDS(ON): VGS = 18 V, ID = 20 A, Ta = 25℃
Qgd: VDD = 800 V, VGS = 18 V, ID = 20 A, Ta = 25℃
(Toshiba internal comparison, as of May 2022)

3. Wide gate-source voltage VGSS specification range

For our 3rd-generation SiC MOSFETs, the specification range of the gate-source voltage is -10 to 25 V, which is wider than that of other companies' products, allows a wider margin for the drive voltage and makes gate drive design  easier. (Recommended drive voltage: VGS_on = 18 V, VGS_off = 0 V)

Wide gate-source voltage V<sub>GSS</sub> specification range
(Toshiba internal comparison based on the datasheet of each company's 1200 V voltage products as of July 2023.)

[Note] Comparison of our 1200 V 3rd generation SiC MOSFETs when RDS(ON) × Qgd is set to 1 in our 2nd generation SiC MOSFETs is set to 1. 

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