Electrical properties of platinum-hydrogen complexes in silicon

Abstract

The interaction between hydrogen and platinum is studied in n- and p-type silicon using deep-level transient spectroscopy. Hydrogen is introduced by wet-chemical etching or during crystal growth. In both cases we find that hydrogen forms only electrically active complexes with platinum. Four platinum-hydrogen related deep levels are identified: E(90) at ${\mathrm{E}}_{\mathrm{C}}$-0.18 eV, E(250) at ${\mathrm{E}}_{\mathrm{C}}$-0.50 eV, H(150) at ${\mathrm{E}}_{\mathrm{V}}$+0.30 eV, and H(210) at ${\mathrm{E}}_{\mathrm{V}}$+0.40 eV. These levels belong to at least three different platinum-hydrogen complexes. Level E(250) is identical to the so-called midgap level in Pt-doped Si, which is believed to control the minority-carrier lifetime in Pt-doped silicon. Level H(150) is an acceptor and is present both in n- and p-type samples after hydrogenation. It belongs to a platinum-hydrogen complex which contains more hydrogen atoms than the complexes responsible for the other hydrogen-related levels. Annealing at temperatures above 600 K results in a complete dissociation of all the platinum-hydrogen related defects and the substitutional platinum concentration is fully restored.