Synthesis of nanowires of Group III antimonides (GaSb and InSb) is studied in detail using two approaches: (i) direct antimonidization of Group III metal droplets and (ii) reactive vapor transport of Group III metals in the presence of antimony in the vapor phase. The diameter of the GaSb nanowires ranged from 30 to 700 nm and length from a few to hundreds of micrometers. GaSb nanowires as long as 1 millimeter have been synthesized using direct antimonidization of large (several millimeters) sized gallium droplets. Reactive vapor transport of Group III metals in the presence of antimony in the vapor phase led to the formation of homoepitaxially oriented GaSb nanowire arrays on top of GaSb crystals. In the case of InSb, 100-nm-thick nanowires were obtained by direct antimonidization of indium droplets. Optical and electrical measurements of the GaSb nanowires, performed using photoluminescence and scanning tunneling spectroscopy, reveal a band gap of ∼0.72 eV, similar to that of bulk GaSb.
The performance of bottom‐contact thin‐film transistor (TFT) structures lags behind that of top‐contact structures owing to the far greater contact resistance. The major sources of the contact resistance in bottom‐contact TFTs are believed to reflect a combination of non‐optimal semiconductor growth morphology on the metallic contact surface and the limited available charge injection area versus top‐contact geometries. As a part of an effort to understand the sources of high charge injection barriers in n‐channel TFTs, the influence of thiol metal contact treatment on the molecular‐level structures of such interfaces is investigated using hexamethyldisilazane (HMDS)‐treated SiO2 gate dielectrics. The focus is on the self‐assembled monolayer (SAM) contact surface treatment methods for bottom‐contact TFTs based on two archetypical n‐type semiconductors, α,ω‐diperfluorohexylquarterthiophene (DFH‐4T) and N,N′bis(n‐octyl)‐dicyanoperylene‐3,4:9,10‐bis(dicarboximide) (PDI‐8CN2). TFT performance can be greatly enhanced, to the level of the top contact device performance in terms of mobility, on/off ratio, and contact resistance. To analyze the molecular‐level film structural changes arising from the contact surface treatment, surface morphologies are characterized by atomic force microscopy (AFM) and scanning tunneling microscopy (STM). The high‐resolution STM images show that the growth orientation of the semiconductor molecules at the gold/SAM/semiconductor interface preserves the molecular long axis orientation along the substrate normal. As a result, the film microstructure is well‐organized for charge transport in the interfacial region.
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.