Do thermal donors reduce the lifetimes of Czochralski-grown silicon crystals?

Abstract

High-performance electronics require long carrier lifetimes within their silicon crystals. This paper reports the effects of thermal donors on the lifetimes of carriers in as-grown n-type silicon crystals grown by the Czochralski method. We grew silicon crystals with two different concentrations of thermal donors using the following two cooling processes: one was cooled with a 4-h halt after detaching the crystal from the melt, and the other was cooled continuously. The crystal grown with the cooling halt contained higher concentrations of thermal donors of the order of 1 × 1013 cm−3, while the crystal without the halt had no thermal donors. The measured bulk lifetimes were in the range of 15–18 ms. We concluded that thermal donors in Czochralski-grown silicon crystals do not act to reduce their lifetimes.