Deep-level transient spectroscopy on p-type silicon crystals containing tungsten impurities

Tungsten deep levels are investigated to clarify energies, which are inconsistent among current research. Hole traps located at 0.41 eV above the top of the valence band are determined to be due to tungsten impurities. The concentration of hole traps is almost one-third of that of the tungsten impurities in the substrates. Similar hole traps are also found in different silicon substrates in which tungsten impurities are thermally diffused from the surface. These facts indicate that the hole traps are truly due to tungsten impurities.