Effects of Heat Treatments and the Li-Doping on the Minority Carrier Lifetime in Dislocation-Free p-Type Silicon

Abstract

We studied the minority carrier lifetime in localized volumes in dislocation free silicon, using laser diode as the carrier injection source (1 mmφ, spot). The minority carrier lifetime can be estimated independent of sample thickness provided the thickness is of about the same order as the carrier diffusion length. The lifetime of the quenched samples increases from the surface to the interior and depends on the quenching speeds. It finally assumes oscillating values with a period of 100)_??_200μm in both quenched and as-grown silicon. By lithium diffusion, the increments of lifetime in A type swirl rich region are larger than those of the swirl lean region in swirl contained silicon. Although the minority carrier lifetimes in samples of silicon quenched from 700°C were not changed, those quenched from 400°C, 500°C and 600°C showed an increase by lithium diffusion.