Bonding 2 Flashcards
Insulators
A solid in which electrons saturate a band and a considerable gap exists between the completely filled band and the next available one
Semiconductors
Electrical properties intermediate between metals and insulators; in semiconductors the forbidden energy gap is relatively small and can be overcome by thermal means of a moderate electrical field
Semiconductors
Unlike metals, semiconductors are substances with electrical conductivities that increase with increasing temperature
Intrinsic semiconductors
A solid in which the band gap is so small that some electrons from the VB will occupy energy levels in the CB
Negative carriers
Electrons in the upper level resulting from the slight electron population in the conduction band
Positive holes
Results when the slight electron population in the conduction band causes these to form in the lower level
Extrinsic semiconductor
A substance that is normally an insulator but if small amounts of atoms are introduced into the lattice become semiconducting
Doping
Process of introducing the impurity
N-type semiconductors
Formed when a doping atom possesses more external electrons than the parent atom.
N-type conductivity
The donor band is close to the conduction band, and the thermal excitation of electrons from the donor band to the empty conduction band enables a current to flow; charge carriers are negative electrons
Acceptor band
Created when the impurity has less external electrons than the parent atom and lies close to and above the filled silicon valence band
P-type conductivity
The charge carriers are positive holes; the process in the valence band can also be seen as a hole moving across a row of atoms, in the direction opposite to the flow of electrons
p-n junctions
Consist are f s p-type semiconductor that’s in close contact with an n-type semiconductor
p-n junctions function part a
A few electrons of the n-zone migrate spontaneously toward the p-type zone; the migration confers a - charge to the p-zone and a + charge to the n-zone
Contact or junction potential
The accumulation of charge at p-n junctions
Inversely polarized
When the junction offers a resistance to the current flow; no current can flow through the system; happens if p-zone is connected to the negative pole and the n-zone the positive pole of a battery
Directly polarized
Current can flow freely; happens when p-zone is connected to the positive energy pole and n-zone the negative pole; flow of e- occurs in the normal direction
Rectifiers
P-n junctions allows the current to flow only in the direction of direct polarization so an AC is turned into a DC
Transistors creation
Made by insetting a p-type semiconductor between two n-type semiconductors; creating 2 interfaces and attaching the (+) & (-) poles so that one applied potential increases the supply of carriers to another potential
Transistors
Acts as an amplifier, when a n-p-n transistor is inserted b/w 2 circuits where I can then take the current in one circuit and produce a proportional current in the other one at a higher potential
Coordinate covalent bonds
When covalent bonds form b/w a transition metal and a polar molecule like water or ammonia
Coordination complexes
Molecules that consist of a transistor metal ion bonded to polar molecules via a coordinate covalent bond; H3B-NH3
Lewis Base
A molecule that donates a pair of electrons to form a covalent bond
Lewis Acid
A molecule that accepts a pair of electrons to form a covalent bond
