Tailoring the Height of Ultrathin PbS Nanosheets and Their Application as Field-Effect Transistors

Abstract

Two-dimensional, solution-processable semiconductor materials are anticipated to be used in low-cost electronic applications, such as transistors and solar cells. Here, lead sulfide nanosheets with a lateral size of several micrometers are synthesized and it is shown how their height can be tuned by the variation of the ligand concentrations. As a consequence of the adjustability of the nanosheets' height between 4 to more than 20 nm charge carriers are in confinement, which has a decisive impact on their electronic properties. This is demonstrated by their use as conduction channel in a field-effect transistor. The experiments show that the performance in terms of current, On/Off ratio, and sub-threshold swing is tunable over a large range.

New ways to synthesize lead sulfide nanosheets—substituted alkanes direct the growth of 2D nanostructures

“…8,9,10,11,18,19 Here, we demonstrated that amines and aliphatic fluorides are also suitable for the growth of twodimensional lead sulfide shapes at reaction temperatures of 170 °C. By omitting the coligand, the only ligand left in the solution is oleic acid.…”

Towards colloidal spintronics through Rashba spin-orbit interaction in lead sulphide nanosheets

“…We synthesized PbS nanosheets with lateral dimensions of up to 5 μm and tunable thickness of 2–20 nm by introducing different amounts of oleic acid to the synthesis192022 (for crystallographic characterization see Supplementary Fig. 1).…”

“…The height of the nanosheets directly determines the band gap of the material by confinement23. This tunability is of advantage for the performance of applications such as transistors, photodetectors and solar cells17182023. The synthesis of the nanosheets is independent of the fabrication of the devices, which makes it practical for industrial applications.…”

“…The solution-based synthesis of colloidal nanomaterials offers enormous opportunities in the production of inexpensive and high-quality crystals for electronic and, as we will show, spintronic devices171819. Colloidal lead sulphide (PbS) nanosheets as continuous 2D crystals with promising properties do not suffer from tunnel barriers like other colloidal systems, such as thin films of nanoparticles171820. However, their rock salt crystal structure is centrosymmetric.…”

Phototransport in colloidal nanoplatelets array

“…Moreover, the 2D aspect of the nanoparticles leads to a high exciton binding energy [7,8] (≈250 meV) and a fast photoluminescence lifetime. While the spectroscopic properties have attracted huge interest in particular for stimulated emission, the integration of NPL [9] into conductive devices remains far less investigated [10,11]. Nevertheless, NPL look promising because their sharp optical features can be used to develop narrow emission electroluminescence devices [12] or photodetectors with finely controlled cut-off wavelengths.…”