Low Drive Voltage High Efficiency SiC Schottky Barrier Diodes

ROHM has announced the development of next-generation SiC (Silicon Carbide) Schottky barrier diodes (SBD), featuring lower loss and higher voltage capability compared to silicon-based SBDs. In addition, the SCS110A series provides advantages over even other SiC SBDs currently on the market regarding forward voltage and operating resistance. This makes them ideal for a wide range of applications, including PFC (power factor correction) circuits, converters, and inverters for power conversion such as those used in EV/HEV and air conditioning units.

In the power electronics sector, conversion losses generated in conventional (Si-based) semiconductor devices have become increasingly problematic, prompting a search for a viable alternative. Silicon carbide (SiC) has emerged as the most promising candidate due to its superior material properties, in particular lower loss.

ROHM has been performing R&D on SiC for years, beginning with the successful development of an SiC MOSFET prototype in 2004, followed by power modules and SBDs. Improvements and enhancements were made to the SiC SBDs based on customer feedback in 2005. This led to the development of a uniform production system for SiC devices and the acquisition of SiCrystal AG (Germany) in order to ensure a stable supply of high-quality SiC wafers.

The SCS110A series of SiC SBDs feature a reverse recovery time (trr) of 15nsec – much less than the 35nsec to 50nsec of conventional Si-based FRDs. As a result, recovery loss is reduced by as much as 2/3rds, decreasing heat generation as well. In addition, the products ensure more stable operation during temperature changes than silicon FRDs, contributing to smaller heat sinks.

Compared with competitor SiC SBDs, the series improves trr and reduces chip size by 15%, along with operating resistance, temperature characteristics, and forward voltage (VF=1.5V at 10A), resulting in greater efficiency. ROHM has also solved the problems associated with the mass production of SiC SBD devices, such as uniformity of the Schottky contact barrier and formation of a high-resistance guard ring layer that does not require high temperature processing, making uniform, in-house production possible.

SiC Schottky Barrier Diode  (PDF：340KB)

■Key Features (SCS110A Series):

• Ultra-small reverse recovery charge (Qrr) enables high-speed switching
• Stable temperature characteristics
• trr (reverse recovery time) characteristics independent of temperature

■Switching Waveform Comparison: Silicon FRD vs. SiC SBD

■Electrical Characteristics

■Terminology

• SiC (Silicon Carbide)
  A compound semiconductor with characteristics superior to silicon, including a band gap approximately 3 times greater, a dielectric breakdown field 10 times higher, and a thermal coefficient 3 times larger. These characteristics make it ideal for power device applications and high-temperature operation.
• Schottky Barrier Diode
  A diode that utilizes the rectifying properties (diode characteristics) of a Schottky junction, in which a metal and a semiconductor are placed in contact with one another. This type of diode features superior speed performance due to the lack of the minority carrier storage effect.
• Schottky Barrier
  The barrier formed due to the Schottky (metal-semiconductor) junction.
• Guard Ring
  Refers to the ring-shaped region formed around the device in order to prevent possible adverse effects due to peripheral components.
• Reverse Recovery Time (trr)
  The time during which there is instantaneous flow of reverse current when the voltage direction has changed from the forward to the reverse direction.