A Semiconductor with Embedded Nanoparticles Invisible to the Conduction Carriers

Applications

This technology can be used to create highly conductive transistors, diodes, and metal–oxide–semiconductor field-effect transistor (MOSFETs). It can also be implemented in very precise electronic switches and filters.

Problem Addressed

Currently, semiconductors are doped to increase carrier density and, theoretically, electrical conductivity. However, doping also increases the carrier scattering cross section which decreases electrical conductivity. The proposed method increases carrier mobility and decreases carrier scattering cross section for a desired energy window. The separation of these properties allows the electrical conductivity and the thermoelectric figure-of-merit to simultaneously increase.

Technology

The key to this design is fabricating carrier donating nanoparticles with a specific potential profile to minimize the electron scattering cross section within the Fermi window, cloaked nanoparticles, to guarantee mobility enhancement. If the scattering cross section versus energy has a large slope at the edges of the Fermi window, anti-resonance scattering, the thermoelectric power factor also increases significantly.  This is done by using core-shell structured nanoparticles - modeled as two-step potential wells - and only modifying the barrier height and well depth. Using this technique a residue scattering cross section smaller than 0.01% of the physical cross section was observed. More remarkably, 4 orders of magnitude difference in total scattering cross section was presented within an energy range of only 40meV. This invention makes it possible to design scattering centers with anti-resonance or cloaking features in a specifically tunable energy range. Using these techniques, materials with almost perfect carrier transmission can be designed. Similarly, an electronic filter is created by tuning the specific energy range and the on-off scattering ratio so only charge carriers in a specific energy range will pass. Finally, by controlling the on-off scattering ratio, proper switches can be designed and used for quantum information storage.

Advantages

  • Simultaneous increase of electrical conductivity and thermoelectric figure-of-merit
  • Ability to create precise electronic filters and switches