We demonstrate experimentally a chemical codoping approach that would simultaneously narrow the band gap and control the band edge positions of oxide semiconductors. Using TiO 2 as an example, we show that a sequential doping scheme with nitrogen (N) leading the way, followed by phosphorous (P), is crucial for the incorporation of both N and P into the anion sites.Various characterization techniques confirm the formation of the N-P bonds, and as a consequence of the chemical codoping, the band gap of the TiO 2 is reduced from 3.0 eV to 1.8 eV. The realization of chemical codoping could be an important step forward in improving the general performance of electronic and optoelectronic materials and devices.
This investigation focuses on the formation of nanoscale puddles of an intermediate metallic phase (IMP) in the metal-insulator transition (MIT) temperature regime of single-crystalline vanadium dioxide (VO2) nanowires. The electronic structure of VO2 nanowires was examined with scanning tunneling spectroscopy. The evolution of the local density of states of individual nanowires throughout the MIT regime is presented with differential tunneling conductance spectra and images measured as the temperature was increased. Our results show that the formation of an IMP plays an important role in the MIT of intrinsic VO2.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.