We present theoretical and experimental studies of Schottky diodes that use aligned arrays of single-walled carbon nanotubes. A simple physical model, taking into account the basic physics of current rectification, can adequately describe the single-tube and array devices. We show that for as-grown array diodes, the rectification ratio, defined by the maximum-to-minimum-current-ratio, is low due to the presence of metallic-single-walled nanotube (SWNT) shunts. These tubes can be eliminated in a single voltage sweep resulting in a high rectification array device. Further analysis also shows that the channel resistance, and not the intrinsic nanotube diode properties, limits the rectification in devices with channel length up to 10 μm.
KEYWORDSSchottky diodes, aligned arrays, single-walled carbon nanotubesSince the earliest days of work on semiconductor devices, diodes have played critically important roles. Theories of p-n Schottky diodes [1, 2] laid the foundations for understanding bi-polar transistor operation and contact phenomena at the metal/semiconductor interface. Even though the diode itself is not a main element of modern digital electronics, the physics of the diode structure is essential for many applications, including in optoelectronics [3]. Nanoscale diodes have been already demonstrated with carbon-based nanomaterials, such as graphene and individual nanotubes [4][5][6][7][8][9][10][11][12][13][14]. The work presented here focuses on diode structures made of parallel nanotube arrays, their rectification properties, and the physics of their electronic transport. The array format is advantageous because they deliver much larger currents than a single-tube device and have less noise, enabling them to operate at high frequency as we have demonstrated Nano Res (2010) 3: 444-451