▲ A Semiconductor

South Korea is famous for the technology of semiconductors. Semiconductors play an important role in equipment control in a variety of fields. Then, what is their main role? First, semiconductors can do rectifying. It is an electrical device that converts alternating current(AC), which periodically reverses the direction, to direct current(DC), which flows in only one direction. In a circuit, the semiconductors play the role of rectifiers. Second, they can also amplify the signal. Semiconductors are used in high technology, and they are basic materials for an arithmetic unit of logic gates like a computer.

The first aim of semiconductors is to control electricity, and this role has steadily been developed. The power of semiconductors is the main component of an inverter. A power inverter is a power electronic device of circuitry that changes direct current(DC) to alternating current(AC). The inverter is one of the most important components of solar panels. However, there is a problem that semiconductors conduct their function in the inverter. Because of the role, there are a lot of current flows. Then, friction heat occurs by following the formula (Heat Energy=I^2RT). At present, power semiconductors are based on the silicon wafer, but, silicon cannot do its function in 150 Celsius and over. Therefore, a cooling system is essential for the use of power semiconductors.

▲ The Heat Energy Formula in calories

Recently, the demand for a power semiconductor with SiC(Silicon Carbide) surges. SiC power semiconductors are made of a compound that is combined with carbon and silicon at a one-to-one ratio. They can withstand about ten times the voltage compared to Si with the same thickness. Furthermore, they can do their roles even at 500 Celsius, and they do not need any cooling system. Thanks to the absence of a cooling system, the volume and weight of an inverter reduce. The energy efficiency of electric car inverters with SiC power semiconductors increases ten percent at maximum compared to Si ones.

It is very important to reduce the resistance in power semiconductors. It is because resistance is proportional to energy loss. To reduce resistance, KERI (Korea Electrotechnology Research Institute)

▲ Previous Structure and Trench Structure

June 12th, by Jiho Kim