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 10(21) 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 ail 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. (C) 2009 Elsevier B.V. All rights reserved.