Performance and photovoltaic response of polymer-doped carbon nanotube p-n diodes.

Two terminal abrupt junction diodes are fabricated from single semiconducting carbon nanotubes with simple photopatterned polymer layers defining air-stable p- and n-regions. These intratube diodes show nearly ideal behavior with relatively low series resistance and no sign of Zener breakdown at room temperature. Spatial doping profiles measured by micro-Raman spectroscopy and selective electrochemical gating of the n-region indicate that diode performance depends strongly on relative doping levels. A short circuit current of 1.4 nA with an open circuit voltage of 205 mV are measured when illuminated to saturation.