Lifetime-controlling recombination centers in platinum-diffused silicon

Abstract

The diffusion of Pt into Si from a silica film at temperatures between 800 and 1000 °C has been found to provide room‐temperature minority‐carrier lifetimes between 10 nsec and 1 μsec. Evaluation of the dependence of lifetime on ambient temperature and on majority‐carrier doping concentration as well as the measurement of thermally stimulated currents indicate the presence of two recombination centers: an acceptor located 0.26 eV below the conduction band edge for n‐type Si and a donor located 0.32 eV above the valence band edge for p‐type Si. The concentration of electrically active Pt centers increases exponentially with increasing diffusion temperature, and is in the range 7×10¹³ to 7×10¹⁴ cm⁻³. Minority‐carrier capture cross sections for the n‐ and p‐type Si are about 1×10⁻¹⁴ and 6×10⁻¹⁵ cm², respectively. A simple single‐level Shockley‐Read model incorporating these centers has been used to fit observed minority‐carrier lifetime values over a wide range of temperature and to calculate the dependence of lifetime on majority‐carrier doping concentration for n‐ and p‐type Si.