On the high end, "laboratory" operation of discrete semiconductor devices has been reported at temperatures as high as about +700°C (for a diamond Schottky diode) and 650°C (for a SiC MOSFET). Integrated circuits based on Si and GaAs have operated to +400−500°C. Si ICs have been reported to operate at +300°C for 1000 hours or longer.
Covering both extremes, there are reports of the same transistor working from about −270°C to about +350 to +400°C, an operating temperature span of over +600°C!