18 Questions
What type of materials contain large densities of free electrons, leading to a strong contribution to the dielectric function?
Metals and heavily doped semiconductors
In a free electron plasma, what happens when the free electrons interact with electromagnetic radiation?
They experience a zero restoring force
What formula can be used to calculate the dielectric function of a metal or a doped semiconductor?
Drude-Lorentz formula
In an ideal metal with zero damping, what is the behavior of the plasma frequency?
It remains constant
Why are metals transparent in the UV region?
They absorb UV light efficiently
What characterizes the dielectric function of a free electron plasma?
It contains a plasma frequency term
What induces a current density J in a metal during a time-varying field?
Finite AC electrical conductivity
In the equation of motion for free electron plasma, what does the symbol 'g' represent?
Reciprocal of the characteristic timescale
What is the relationship between momentum scattering time and momentum loss in free electron plasma?
Inversely proportional
How does the velocity v(t) in free electron plasma behave with respect to time?
Has a harmonic time dependence
What does the dielectric function of a free electron plasma represent?
AC conductivity measurements
Which term in the equation Ne 2 / s(w) represents the AC conductivity in free electron plasma?
(1/t - iw)
What type of transitions occur in semiconductors during inter-band transitions?
Valence Band to Conducting Band transitions
How can mid-bandgap states in wide bandgap materials be created for optical activity?
Adding impurities
What gives metals their characteristic shiny appearance?
Free electron interactions with light
In which part of the spectrum does free carrier absorption typically occur in semiconductors?
Infrared (IR)
What is a common method to introduce 'Colour centres' in materials like sapphire?
Ion beam or X-ray irradiation
What is a characteristic feature of the optical response of all insulators and semiconductors?
A very characteristic form in T(E)
Explore the range over which semiconductors and their nanostructures can generate and detect electromagnetic radiation from ultraviolet to microwave. Learn about the properties of metals, insulators like diamond and sapphire, as well as semiconductors like ZnSe.
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