2007/07/21 by Y. H. Ahn, Wei Tsen, A. W. Tsen +3 · 1 citation
Engineering · Materials Science · Neuroscience · Physics and Astronomy · #Ambipolar diffusion #Carbon Nanotubes in Composites #Carbon nanotube #Carbon nanotube field-effect transistor #Conductance #Microscopy #Nanofabrication and Lithography Techniques #Nanometre #Neuroscience and Neural Engineering #Photocurrent #cond-mat.mes-hall #cond-mat.mtrl-sci
paper · pdf · doi:10.1021/nl071536m
5 pages, 5 figures
arxiv created 2007/07/21 · openalex publication_date 2007/10/16 · arxiv updated 2015/05/12 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We use scanning photocurrent microscopy (SPCM) to investigate the properties of internal p-n junctions in ambipolar carbon nanotube (CNT) transistors. Our SPCM images show strong signals near metal contacts whose polarity and positions change depending on the gate bias. SPCM images analyzed in conjunction with the overall conductance also indicate the existence and gate-dependent evolution of internal p-n junctions near contacts in the n-type operation regime. To determine the p-n junction position and the depletion width with a nanometer scale resolution, a Gaussian fit was used. We also measure the electric potential profile of partially suspended CNT devices at different gate biases, which shows that induced local fields can be imaged using the SPCM technique. Our experiment clearly demonstrates that SPCM is a valuable tool for imaging and optimizing electrical and optoelectronic properties of CNT based devices.