ABSTRACT
A plot of electron affinity (EA) and ionization potential (IP) versus energy band gap (E(G)) for 69 binary closed-shell inorganic semiconductors and insulators reveals that E(G) is centered about the hydrogen donor/acceptor ionization energy ε(+/-). Thus, ε(+/-), or equivalently the standard hydrogen electrode (SHE) energy, functions as an absolute energy reference, determining the tendency of an atom to be either a cation or anion in a compound. This empirical trend establishes the basis for defining a new solid state energy (SSE) scale. This SSE scale makes possible simple approaches for quantitatively assessing electronegativity, chemical hardness, and ionicity, while also providing new insight into the periodic trends of solids.
ABSTRACT
A method for achieving large area integration of nanowires into electrically accessible device structures remains a major challenge. We have achieved directed growth and integration of ZnO nanobridge devices using photolithographically patterned carbonized photoresist and vapor transport. This carbonized photoresist method avoids the use of metal catalysts, seed layers, and pick and place processes. Growth and electrical connection take place simultaneously for many devices. Electrical measurements on carbonized photoresist/ZnO nanobridge/carbonized photoresist structures configured as three-terminal field effect devices indicate bottom gate modulation of the conductivity of the n-type ZnO channel. Nanobridge devices were found to perform well as ultraviolet and gas sensors, and were characterized as regards ultraviolet light pulsing, oxygen concentration, and humidity. The sensitivity of the three-terminal nanobridge sensors to UV light and oxygen was enhanced by application of a negative bottom gate voltage.
