Doping Flashcards
How can we manipulate the concentrations of electrons and holes?
Doping
What is Doping?
Atoms of other elements replace Si atoms in the crystal lattice
Most typical elements for Si Doping?
Boron (B) - 5 Atomic numbers
Phosphorus (P) - 15 Atomic numbers
Boron
Is an Acceptor because of his 3 valence electrons (NA)
Phosphorous
Is an Donor because of its 5 valence electron (ND)
How the concentrations of charge carriers inside a semiconductor are derived?
Assuming the semiconductor is under thermal equilibrium
What is the Thermal Equilibrium on a semiconductor?
Is used to describe the unperturbed state of a system, to which no external voltage, magnetic field, illumination, mechanical stress, or other
perturbing forces are applied. In the equilibrium state, the observable parameters of a semiconductor do not change with time.
What is the Fermi Level?
The electrochemical potential of the electrons in a material and in this way it represents the averaged energy of electrons in the material.
Amount of Thermal energy level
KBT at 300 K =26.85°C 0.0258 eV
Relation in a Intrinsic Semiconductor in equilibrium
n = p = ni
n X p in an Intrinsic Semiconductor
nxp=ni*2
The two basic transport mechanisms in a semiconductor
Drift and Diffusion
Define Mobility
Measure of how easily the charge particles can move through a semiconductor material
Drift
Charged particle motion in response to an electric field. In an electric field the force acts on the charged particles in a semiconductor, which accelerates the positively
charged holes in the direction of the electric field and the negatively charged electrons in the opposite direction.
Diffusion
Process whereby particles tend to spread out from regions of high particle concentration into regions of low particle concentration as a result of random thermal motion.
What is the driving force for the Diffusion Motion?
Gradient in the particle concentration.
