NTD Silicon on High Power Devices

Abstract

High power rectifiers and thyristors are generally fabricated with float zone silicon material. The resistivity variations of this type of material produce non-uniform electrical characteristics from device to device, especially in blocking voltage, forward voltage drop, and switching characteristics. Large area NTD (neutron transmutation doped) silicon¹ has become available from different suppliers since 1975. This type of silicon has a narrow range of resistivity across the whole area. During the last few years, we have evaluated and manufactured 50mm to 67mm diameter high resistivity NTD silicon for high power devices. Devices fabricated from this type of material resulted in a higher voltage distribution and a narrower distribution of electrical characteristics.