In NMOS (n-type metal-oxide-semiconductor) transistors, the transistor channels comprise n-type semiconductor material, in which electrons comprise the majority of charge carriers, and holes are the carriers that store charge. The n-type channels of such devices are sometimes formed in a bulk substrate that comprises a p-type semiconductor material, in which the majority of charge carriers comprise holes. The memory data retention times of some nMOS transistors (e.g., floating body effect-(FBE-) based ITOC DRAM cells) depend at least partially upon the length of time that the holes, which have a tendency to “travel” into the p-type semiconductor material of the bulk substrate, may be retained within the n-type channels.