Intermediate band mobility in heavily titanium-doped silicon layers

The sheet resistance and the Hall mobility of high-purity Si wafers, in whose surface Ti atoms are implanted and laser annealed reaching concentrations above 1021 cm−3, are measured in the 90–370 K range. Below 240 K, an unconventional behavior is observed that is well explained on the basis of the appearance of an intermediate band (IB) region able to form a blocking junction with the substrate and of the appearance of an IB conduction. Explanations based on ordinary device physics fail to justify all the unconventional behavior of the characteristics observed.