Radiation Induced Single Ion Surface Effects in Nanoelectronic Circuits

Due to their small physical size, carbon nanotubes (CNTs) and other molecular systems are highly susceptible to changes in individual defect or charge states nearby or in contact with the device. As increasing numbers of deeply scaled micro- and nano-electronic devices are used in space systems, effects such as this will become more important. Several important radiation studies on CNT based field effect transistor (FET) devices have shown marginal to minimal sensitivity to TID; however, to the authors' knowledge, no reports have been made concerning the observation of transient radiation effects such as single event effects in CNT FET devices. Here, we report on electrical measurements of CNT FETs exposed to ionizing proton and gamma radiation that show large, sudden, quantized increases in electrical resistance of the device by over two orders of magnitude. These transient radiation effects are attributed to individual ionized gas molecules adsorbing to the surface of and interacting with the CNT FET devices. This hypothesis is supported by electrical measurements showing quantized resistance increases during ion exposure, by ion drift chamber measurements that show transients only during exposure to positive ions, and by exposure to ions generated by corona discharge, in the absence of radiation. These results demonstrate that as electronics are ultimately scaled towards the one-dimensional limit, radiation effects at the single defect limit become more important.