GOLD IMPLANTATION IN N-TYPE SILICON - ENTROPY FACTOR AND DIFFUSION STUDIES

Rutherford backscattering spectrometry and spreading resistance techniques have been used to determine the concentration profiles of gold implanted and diffused in n-type silicon. Diffusion has been performed at 1243 K for times ranging between 1 and 20 h in a dry-nitrogen flux. Resistivity profiles were transformed into concentration profiles by solving the charge balance equation. The entropy factor for the ionization of gold acceptor level was determined to be 50±5. By using this value and solving the charge balance equation we have calculated the silicon resistivity versus gold concentration (and therefore minority-carrier lifetime) curves as a function of the resistivity of starting material. Experimental gold concentration profiles were compared to the profiles obtained by numerical solution of the diffusion equation for gold in silicon. The measured diffusion coefficients coincide with the values determined for p-type material.