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Solid State Devices
Quiz 1 Review
Question | Answer |
---|---|
What is a semiconductor? | a material whose electrical conductivity can be controlled over a wide range from near-insulating to metal-like conducting. |
What property makes semiconductors special for electronic device applications? | engineerable conductivity |
The following are semiconductors... | Silicon(Si),Germanium(Ge),Diamond,Gallium Nitride(GaN) |
Energy bandgap is? | the span of energies that lie between the valence and conduction bands for insulators and semiconductors. |
A unit cell is | the smallest part of a crystal that has no periodicity in itself. |
The lattice constant is | one of the dimensions of a unit cell. |
Where can you find GaAs? | Cell phone, TV remote, TV satellite dish |
Why is crystalline semiconductor more desirable than polycrystalline and amorphous? | because electron speed is much faster in crystalline. |
Where do most of today's semiconductors come from? | they are made by industries. |
Why do people try so hard to grow semiconductors rather than take it from nature? | because they want a very pure crystal. |
How many crystals do people want to get, when they grow a big boule? | just a single crystal. |
Epitaxial growth means: | the growth of a semiconductor on the surface of a semiconductor. |
Why do impurities matter? | Impurities affect the transport properties of a semiconductor. It can make semiconductors highly conducting (shallow donors or acceptors) or highly insulating (deep traps). |
True or False: Impurities will always make a semiconductor useless. | False. |
Doping means... | to put certain atoms in a semiconductor or the insertion of controlled impurities. |
A doped semiconductor: | has a different electrical conductivity than before doped. |
An unintentionally doped semiconductor is: | a semiconductor that gets doped accidentally during the growth. |
True or False: A zero-impurity polycrystalline semiconductor is always more valuable than a single-crystal semiconductor with impurities. | False. Controllable impurities are desirable because this is how we make devices. |
Can you just buy raw semiconductors (not in a circuit)? | Yes. |
What were the motivations for people to develop semiconductors? | To have materials whose electrical conductivity can be controlled. |
Before the development of semiconductor devices, people: | did computation with mechanical devices(e.g. abacus, mechanical gears, etc.) and metal and glass-bulb electrical devices. |
The development of semiconductor devices improved what? | Radio, telephone, wireless communication. |