Metal-oxide nanocrystals doped with aliovalent atoms can exhibit tunable infrared localized surface plasmon resonances (LSPRs). Yet, the range of dopant types and concentrations remains limited for many metal-oxide hosts, largely because of the difficulty in establishing reaction kinetics that favors dopant incorporation by using the co-thermolysis method. Here we develop cation-exchange reactions to introduce p-type dopants (Cu +, Ag +, etc.) into n-type metal-oxide nanocrystals, producing programmable LSPR redshifts due to dopant compensation. We further demonstrate that enhanced n-type doping can be realized via sequential cation-exchange reactions mediated by the Cu + ions.
- Semiconductor And Metal Nanocrystals Pdf - Free Software And Shareware Music
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Semiconductor And Metal Nanocrystals Pdf - Free Software And Shareware Music
Cation-exchange transformations add a new dimension to the design of plasmonic nanocrystals, allowing preformed nanocrystals to be used as templates to create compositionally diverse nanocrystals with well-defined LSPR characteristics. The ability to tailor the doping profile postsynthetically opens the door to a multitude of opportunities to deepen our understanding of the relationship between local structure and LSPR properties.
Doping, the intentional introduction of impurity atoms into a host lattice, is an essential process for developing semiconductor materials and devices. Over the past three decades, researchers have been studying how foreign atoms can be controllably incorporated into semiconductor nanocrystals (NCs) in order to tailor their optical and electronic properties,. In bulk semiconductors, substitutional dopant atoms with extra valence electrons can introduce shallow donor levels below the conduction band and when thermally ionized can produce n-type semiconductors that contain excess electrons. These electrons (or holes for p-type doping) are available as mobile charge carriers responsible for current transport. In semiconductor NCs, the collective oscillation of confined charge carriers in response to incident radiation can lead to the so-called localized surface plasmon resonance (LSPR),.The field of plasmonics can benefit greatly from the development of new nanomaterials with tunable carrier concentration and carrier dynamics,. Distinct from conventional metal-based plasmonic materials for which electron density is largely fixed and postsynthetic variation is typically not possible, the carrier density and thereby the LSPR energies of semiconductor NCs made of metal oxides, chalcogenides, phosphides, nitrides, and silicon can be synthetically adjusted to cover the near-infrared (NIR) and the mid-infrared regions.
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The unique plasmonic properties of semiconductor NCs are being harnessed for new applications and technologies including but not limited to surface-enhanced infrared absorption spectroscopy (SEIRAS), smart windows, low-loss optical metamaterials, and bioimaging. During the past 5 years, impressive progress has been made toward the syntheses of various plasmonic metal-oxide NCs, such as tin-doped In 2O 3 (ITO).