US researchers say they\'ve joined a conductor and insulator into a single atoms-thick layer that may advance the ability to shrink electronic devices. Scientists at Rice University in Houston say the material -- graphene as a conductor and hexagonal boron nitride as an insulator -- have been merged into sheets and built into a variety of patterns at nanoscale dimensions. Researchers say the technique suggests the possibility of building 2-D, atomic-layer circuits that could offer manufacturers the possibility of condensing electronic devices into even smaller packages. While the Rice researchers have created sheets with features to a resolution of about 100 nanometers, they say the only real limits are those defined by modern lithographic printing techniques. (A nanometer is one-billionth of a meter.) \"It should be possible to make fully functional devices with circuits 30, even 20 nanometers wide, all in two dimensions,\" Rice researcher Jun Lou said in a university release Sunday.