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Nanoelectronics - Coggle Diagram

- - - - Atoms are held tightly in place
        
        Prevent electromigration
        
        prevent short circuit or open circuit due to the formation of hillocks and grooves within the material
    - - Scattering occurs due to collision of electrons with impurities, defects or atoms and molecules that are composed in the medium (oscillating around their equilibrium position)
        
        Therefore, mean free path > dimension of the carbon nanotube, ballistic conduction occurs.
        
        Negligible heat dissipation
        
        Hence, carbon nanotubes can be used as interconnects in miniaturized electronic circuits
  - - - Have the highest tensile strength of the materials discovered (about 63GPa)
    - - Standard single-walled nanotube can withstand a maximum pressure of 25-55GPa, without deforming
    - - Stiffest (high elastic modulus) of all materials discovered
  - - - The starting (0, 0) carbon atom can be joined to any other carbon atom to form (n, m) carbon nanotube
        
        Armchair pattern
        
        (n, n)
        
        Zigzag pattern
        
        (n, 0) or (0, m)
        
        Chiral pattern
        
        (n, m)
      - Attaching to different carbon atom results in different structures and size of the carbon nanotubes
        
        Diameter of carbon nanotube, d, where a =0.246nm and n/m is the chiral indices
        
        Diameter is inversely proportional to the band gap, smaller the diameter, greater the band gap.
        
        Larger diameter, with reduced band gap, is more desirable for the carbon nanotube to act as a semiconductor, and able to conduct electricity.
        
        At nanoscale, electrons propagate along the cross-section of the tube's axis
        
        1-demensional conductors
    - - All armchair patterns are metallic, as it fulfills the criteria, n=m
  - - - Larger mean free path, electrons can travel over a larger distance without collision and scattering
        
        Resistivity is reduced, higher conductivity
- - - - Electrons does not have enough energy to overcome the large barrier size, in the absence of voltage
    - - Therefore, by controlling the voltage applied, at the gate electrode, the passage for the flow of single electrons can be controlled
    - - Energy required is inversely proportional to the diameter of the nanoparticles
        
        When U > the thermal energy at room temperature (4 x 10^-21J), in the absence of gate voltage, electrons does not possess enough energy for tunneling, no conduction, SET is switched off
        
        When U < 4 x 10^-21J, in the absence of gate voltage, there is sufficient thermal energy to charge the electrons for conduction to occur and SET remain switched on (not desirable)
        
        Reduce the size of the nanoparticles (diameter in m) to increase the energy needed to tunneling to occur, inverse proportion
- - - - Leading to the increased in resistance and more heat being generated and could cause the reliability to decrease
    - - Allow current to flow through the interconnects at a lower resistance
        
        Therefore, signals can be transmitted.
    - - More frequent collision occurs when current density and temperature are high
        
        As particles/ions are displaced from the original position by the electrons in the presence of an electric field
        
        Due to the transfer of momentum
        
        Direction of movement of ions depends on the direction of collision with the electrons
        
        Formation of defects such as hillocks and vacancies
        
        Creates short-circuit when the ions of two interconnects joined together, and open-circuit when the displacement of ions form voids, such that electrons cannot flow through
      - All conductors are susceptible to electro-migration, but the chances of electro-migration can be reduced at lower temperature and lower electron density.
    - - More scattering events as electrons collide with the side walls and grain boundaries defects, higher the resistivity of material
        
        Resistance to current flow increases
        
        More heat will be generated per cm^2 as electronic device advances and miniaturized contributing to reliability issues