Single Carbon Nanotube Schottky Diode Microwave Rectifiers

We report the fabrication of single and few-channel carbon nanotube (CNT) Schottky diodes on high-frequency compatible substrates using horizontally aligned CNT arrays and dissimilar metal contacts in a coplanar-waveguide geometry. Rectification of ac signals in the range of 100 MHz-40 GHz is examined and the observed cutoff frequencies are used to compute the Schottky junction capacitance of the devices, which is strongly CNT-length-dependent and appears dominated by stray capacitance between the CNT channel and metal electrode, in agreement with electrostatic simulations.