Direct coupling of electronic excitations of optical energy via plasmon resonances opens the door to improving gain and selectivity in various optoelectronic applications. We report a new device structure and working mechanisms for plasmon resonance energy detection and electric conversion based on a thin film transistor device with a metal nanostructure incorporated in it. This plasmon field effect transistor collects the plasmonically induced hot electrons from the physically isolated metal nanostructures. These hot electrons contribute to the amplification of the drain current. The internal electric field and quantum tunneling effect at the metal-semiconductor junction enable highly efficient hot electron collection and amplification. Combined with the versatility of plasmonic nanostructures in wavelength tunability, this device architecture offers an ultrawide spectral range that can be used in various applications.

A zinc oxide nanowire (ZnO NW)-embedded Schottky diode was fabricated for UV detection. Two types of devices were prepared. The ZnO NW was positioned onto asymmetric metal electrodes (Al and Pt) for a Schottky device or symmetric metal electrodes (Al and Al) for an ohmic device, respectively. The Schottky device provided a rectifying current flow and was more sensitive to UV illumination than the ohmic device. The Schottky barrier plays an important role for UV detection by a UV-induced barrier reduction effect. The fabrication of the ZnO NW-embedded Schottky diode and the UV reaction mechanism are discussed in light of the UV light-induced Schottky barrier reduction effect.

Could nanostructures act as lenses to focus incident light for efficient utilization of photovoltaics? Is it possible, in order to avoid serious recombination loss, to realize periodic nanostructures in solar cells without direct etching in a light absorbing semiconductor? Here we propose and demonstrate a promising architecture to shape nanolenses on a planar semiconductor. Optically transparent and electrically conductive nanolenses simultaneously provide the optical benefit of modulating the incident light and the electrical advantage of supporting carrier transportation. A transparent indium-tin-oxide (ITO) nanolens was designed to focus the incident light-spectrum in focal lengths overlapping to a strong electric field region for high carrier collection efficiency. The ITO nanolens effectively broadens near-zero reflection and provides high tolerance to the incident light angles. We present a record high light-conversion efficiency of 16.0% for a periodic nanostructured Si solar cell.