Electrons on dislocations



The electrical behaviour of only a few dislocations was analysed. Such small numbers of defined dislocations were produced by hydrophobic semiconductor wafer direct bonding. The dislocation networks were placed in the channel of SOI MOSFETs where the source and drain regions of these devices act as contacts. Varying the channel width allows one to control the number of dislocations measured. Analyses of nMOSFETs proved an increase of the drain current caused by dislocations by more than one order of magnitude, while a decrease of the current is obtained for pMOSFETs. This indicates that electrons are present on the dislocation core in p-type material. The concentration of electrons on dislocations was estimated to be about 200 electrons per micrometer dislocation length, corresponding to a distance of about 5 nm between free electrons. This distance agrees with the space between Coulomb islands proved by low-temperature measurements. The investigations refer to a metallic-like conductance along dislocations caused by a two-dimensional carrier confinement. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)