Comparison of Modern Devices:
Comparison of Modern Devices – SITH is the largest power device and SIT is the highest frequency device in the present state of technology. It is not possible to compare exactly since devices with compatible power ratings are not simply available. SIT is a very high frequency high power device, but it has the serious problem of large conduction drop. Hence it should not be included in most of the power electronics applications. The SITH is the only current-controlled device with very poor turn-off current gain and is also sluggish compared to other devices. All the devices currently possess an asymmetric voltage blocking capability. Although IGBT, SIT and SITH have somewhat linear characteristics in the active region, only IGBT will pull into high dissipation active mode for fault condition, whereas the other devices will remain saturated due to almost vertical I-V characteristics. It seems that the MCT has the best combination of conduction drop, junction temperature, dv/dt, di/dt and the switching speed is only next to SIT.
Recent Trends of Power Semiconductors
The recent trends in Power Semiconductors from application point of view show that MOSFETs and IGBTs are replacing BJTs almost completely while GTOs are currently being used for high V and power ratings (> 0.5 MVA), these are expected to be replaced by IGBTs and recently introduced IGCTs (integrated Gate Commutated Thyristors) due to power density and performance considerations.
All power semiconductor devices at present employ silicon as the basic material. However, the new type of materials such as gallium arsenide, silicon carbide and diamond show a great promise for future generation of devices. Further, super conductive power control devices based on Josephson effect also show future promise.