... purity silicon 2:float zone technology 3:low cost 4:IGBT use ApplicationPower rectifiers, power transistors, diodes, switching devices the FZ ... is pri-heated by means of a graphite heater.After pre-heating,the graphite heater is swung away and the cone_shaped ingot ... .they are mainly used in GTR,GTO,SCR,IPM,PIM IGBT use mono silicon wafer