Noncontact minority-carrier lifetime measurement at elevated temperatures for metal-doped Czochralski silicon crystals

Abstract

Minority-carrier recombination lifetimes have been extensively measured with a noncontact laser/microwave method for metal-doped p-type Czochralski silicon crystals in the temperature range from room temperature to 250 °C. The contrasting behavior of the lifetime as a function of temperature is shown for Fe- and Cr-doped silicon crystals. Iron doping greatly shortens the lifetime in the entire temperature range. Although Cr doping also greatly shortens at room temperature, the degradation effect completely disappears at elevated temperatures. Doping the Na, Ni, Cu, and W shows little effect on lifetime; Na doping results in a rather higher lifetime compared with that of undoped silicon. Moreover, lifetime measurement as a function of holding time at an elevated temperature clearly distinguishes uncontaminated silicon from metal-doped silicon.