Nanotube electronic devices exhibit selective affinity to disparate nanotube types. According to an example embodiment, a semiconductor device exhibits a treated substrate that selectively interacts (e.g., chemically) with nanotubes of a first type, relative to nanotubes of a second type, the respective types including semiconducting-type and metallic-type nanotubes. The selective interaction is used to set device configuration characteristics based upon the nanotube type. This selective-interaction approach can be used to set the type, and/or characteristics of nanotubes in the device.