This article describes the characteristics of the power semiconductor devices.
Power Electronic Device, also known as power semiconductor device, is used in high-power (usually refers to currents of tens to thousands of amps, voltages of hundreds of volts or more) electronic devices in electrical energy conversion and power control circuits. It can be divided into semi-controlled devices, fully-controlled devices and uncontrollable devices. The thyristors are semi-controlled devices with the highest voltage and current capacity among all devices. Power diodes are uncontrollable devices with simple structure and principle and work reliable; can also be divided into voltage-driven devices and current-driven devices.
IEGT (InjecTIonEnhancedGateTrangistor)
In recent years, Toshiba Corporation of Japan has developed the IEGT. Like the IGBT, it is also divided into a planar gate and a trench gate. IEGT combines some of the advantages of both IGBT and GTO: low saturation voltage drop, wide safe operating area (absorption loop capacity is only about 1/10 of GTO), low gate drive power (2 times lower than GTO) Order of magnitude) and higher operating frequency. In addition, the device adopts a flat plate crimping electrode lead-out structure, which is expected to have high reliability.
The main feature of the IEGT structure is that the gate length Lg is long, and the lateral resistance of the N-long base region near the gate side is relatively high. Therefore, the holes in the N-long base region are injected from the collector, unlike in the IGBT, smoothly. The lateral direction flows into the emitter through the P region, but a layer of hole accumulation is formed in the region. In order to maintain the electrical neutrality of the region, the emitter must inject a large amount of electrons into the N long base region through the N channel. In this way, a high concentration of carrier accumulation is formed on the emitter side of the N long base region, and a carrier distribution similar to that in the GTO is formed in the N long base region, thereby solving the high current and high withstand voltage contradiction. The device has now reached the level of 4.5kV / 1kA.
Gallium arsenide diode
As the switching frequency of the converter continues to increase, the requirements for fast recovery diodes also increase. As is well known, gallium arsenide diodes have superior high-frequency switching characteristics than silicon diodes. However, due to process technology and the like, gallium arsenide diodes have low withstand voltage and are limited in practical applications. Compared with silicon fast recovery diodes, the new diodes are characterized by low reverse leakage current with low temperature, low switching losses, and good reverse recovery characteristics.
MOS gated thyristor
The MOS gate-controlled thyristor makes full use of the good on-state characteristics of the thyristor, excellent turn-on and turn-off characteristics, and is expected to have excellent self-shutdown dynamic characteristics, very low on-state voltage drop and high voltage resistance. MOS gated thyristors mainly have three structures: MOS field-controlled thyristor (MCT), base resistance-controlled thyristor (BRT), and emitter-switched thyristor (EST). Among them EST may be the most promising structure in MOS gated thyristors. However, this kind of device has to become a commercial and practical device, and it takes a long time to replace the GTO level.
13. Silicon Carbide and Silicon Carbide (SiC) Power Devices
Among power devices made with new semiconductor materials, the most promising are silicon carbide (SiC) power devices. Its performance index is an order of magnitude higher than that of gallium arsenide devices. Compared with other semiconductor materials, silicon carbide has the following excellent physical characteristics: high band gap, high saturation electron drift speed, and high breakdown strength. Low dielectric constant and high thermal conductivity. These excellent physical properties determine that silicon carbide is an ideal semiconductor material for high temperature, high frequency, high power applications. Under the same withstand voltage and current conditions, the drift region resistance of SiC devices is 200 times lower than that of silicon, even the conduction voltage drop of high-voltage SiC FETs is better than that of unipolar and bipolar silicon devices lower. Moreover, SiC devices have a switching time of up to 10 nS and have a very good FBSOA.
SiC can be used to fabricate RF and microwave power devices, various high frequency rectifiers, MESFETS, MOSFETS and JFETS. SiC high frequency power devices have been successfully developed at Motorola and used in microwave and RF devices. GE is developing SiC power devices and high temperature devices (including sensors for jet engines). Westinghouse has produced very high frequency MESFETs operating at 26 GHz. ABB is developing high-power, high-voltage SiC rectifiers and other SiC low-frequency power devices for industrial and power systems.
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