Conductivity & Band Structure Flashcards
Explain Ohm’s law
Electric potential difference (V) is linearly proportional to current (I) and resistance (R)
What are properties that are independent of sample size and geometry
Resistivity, Conductivity
Explain resistance vs resistivity
Resistance (R) can be thought of how much current is blocked, like water, depends on size (length and width) and geometry of the wire. Resistivity (rho) is the ability of a substance to carry electric current which changes with temperature (it’s a material property)
Explain conductance vs conductivity
Conductance (G) depends on the inverse of the resistance, whereas conductivity (sigma) is dependent on length and other factors
Explain Ohm’s law in terms of electron flux
J = sigma ep J = current density ep = electric field potential/voltage gradient = V/length
What is drift velocity
Drift velocity is the average electron velocity in the direction opposite of applied force (electrical field)
What is matthiessen’s rule
Presence of imperfections (anything that flaws lattice) increases resistivity, e.g. dislocations, impurity atoms, and vacancies.
Resistivity increases with
temperature, wt%, %cold working
The highest energy band that is at least partially occupied is known as the
valence band
As the bands below the valence band are called
core bands. They are fully occupied bands with no net movement of electrons
The energy band above the valence band is called the
conduction band.
The term band gap
refers to the magnitude of the forbidden energy range between the valence and conduction bands.
Draw out some electron energy band structures for metals, insulators, and semiconductors
For metals, what factors decrease mobility
increasing temperature, adding imperfections, plastic deformation, and distortions from a perfect lattice
