Shottky Diodes Based on Silicon CarbideA Shottky diode is a semiconductor diode with a low voltage drop in direct connection. It was named in honour of the German physicist Walter Shottky. Shottky diodes use metal-semiconductor junctions as Shottky barriers (instead of a p-n junction as in regular diodes).The main properties of Shottky diodes determine their area of application. They have low direct voltage drop and high response speed. Reverse recovery charge is almost absent.The reverse voltage of mass manufactured Shottky diodes is limited by 250V. In reality, most Shottky diodes are used in low voltage circuits at reverse voltages ranging from 1 to several tens of Volts. However, if you use silicon-carbide substrates (Silicon Carbide - SiC) as the base, the operating voltage can be increased up to 1200 Volts.Crystalline silicon carbide was first created in 1892. Then it received the name of carborundum. William Shockley, the inventor of transistors, said that silicon carbide was the perfect semiconductor. He was sure that by 1950 this material would completely replace silicon due to its excellent properties.Silicone carbide is a semiconductor with an indirect energy-band structure. The width of the band gap varies from 2.4 to 3.3 electronvolts. This means a wide range of working temperatures (in theory it's up to 1000 Celsius degrees while in reality it reaches 600 Celsius degrees). It also provides for low leakage current (of less than 70 microamperes at 200 Celsius degrees).The material is corrosion resistant at temperatures of up to 1400 Celsius degrees. It doesn't interact with any acids at room temperature. This explains why it is so hard to make semiconductor devices using this material.Silicon carbide has a high thermal conductivity (approximately equal to that of copper). Thus it is easier to remove heat. Compared to silicon, the thermal resistance of silicon carbide crystals is 2 times smaller. Besides, this material has a critical breakdown field ten times higher than that of silicon.The above mentioned characteristics are responsible for the excellent properties of silicon carbide Shottky diodes which include:- the recovery time of main charge carriers at commutation is extremely low (almost equal to zero);- a higher breakdown voltage, if compared to silicon devices;- high working temperature (up to 175 Celsius degrees);- high frequency of switching (up to 500 kHz). This allows decreasing the size of electromagnetic interference filter ...

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