Optoelectronic Switching of a Carbon Nanotube Chiral Junction Imaged with Nanometer Spatial Resolution

Abstract

Chiral junctions of carbon nanotubes have the potential of serving as optically or electrically controllable switches. To investigate optoelectronic tuning of a chiral junction, we stamp carbon nanotubes onto a transparent gold surface and locate a tube with a semiconducting-metallic junction. We image topography, laser absorption at 532 nm, and measure I-V curves of the junction with nanometer spatial resolution. The bandgaps on both sides of the junction depend on the applied tip field (Stark effect), so the semiconducting-metallic nature of the junction can be tuned by varying the electric field from the STM tip. Although absolute field values can only be estimated because of the unknown tip geometry, the bandgap shifts are larger than expected from the tip field alone, so optical rectification of the laser and carrier generation by the laser must also affect the bandgap switching of the chiral junction.

Nanoscale properties of lead halide perovskites by scanning tunneling microscopy

“…These are the result of the short tip-sample distance on the order of nanometers required for quantum tunneling. 35 It has previously been shown that activation energies below 1 eV are sufficient to displace ions in the perovskite material and distort the perovskite lattice where the migration activation energies are the lowest for the halides followed by the A-site cations. [55][56][57][58] This results in various, and most of the time unpredictable and unforeseen, surface and bulk structures depending on the strength and polarity of the electric field.…”

“…In addition, strong electric fields emerge at the tip/sample junction due to the mandatory voltage which must be applied to either the tip or to the sample in STM experiments. 35 These requirements pose significant challenges with respect to lead halide perovskites where the ABX 3 crystal structure (A-site: organic or inorganic cation[s], B-site: lead, C-site: halides, eg, Cl, Br, I) also mirrors the weak point in these materials: the soft, dynamic and ionic bonding character of the crystal lattice. 36,37 In this critical review, we highlight the recent progress in applying STM-based techniques to organic/inorganic and all-inorganic lead halide perovskites, both in form of single crystals and thin films.…”

“…In particular, to obtain atomic resolution a flat surface is required in addition to the overall requirement of the sample's (semi‐)conductivity to enable the process of quantum tunneling. In addition, strong electric fields emerge at the tip/sample junction due to the mandatory voltage which must be applied to either the tip or to the sample in STM experiments 35 . These requirements pose significant challenges with respect to lead halide perovskites where the ABX 3 crystal structure (A‐site: organic or inorganic cation[s], B‐site: lead, C‐site: halides, eg, Cl, Br, I) also mirrors the weak point in these materials: the soft, dynamic and ionic bonding character of the crystal lattice 36,37 …”

Carbon nanomaterials and their application to electrochemical sensors: a review

“…An additional application of CNTs is as nano-probes. Here, carbon nano-probes can be exploited as atomic force microscopy [174,175] or scanning tunnelling microscope [176,177] tips.…”

Molecular doping of single-walled carbon nanotube transistors: optoelectronic study

“…Due to the unique electronic properties of single-walled carbon nanotubes (SWCNT) [1][2][3] , these quasi-one-dimensional materials have been widely investigated and applied in various device systems, such as field effect transistors (FET) 4 , optical switches 5 , organic photovoltaics (OPV) 6 and organic light emitting diodes (OLED) 7 . Charge dynamics at the interface between SWCNT and organic molecules/metals is of particular importance for the fundamental understanding of carbon-based electronic materials as well as for the development of new types of devices in organic electronics.…”