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MMET 206 > Semiconductors > Flashcards

Semiconductors Flashcards

1
Q

LED

A

Light Emmitting Diode Semiconductor

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2
Q

Efficiency of LEDs

A

250 lumens and conusumes 85% less energy than a standard 60W incandescent light bulb

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3
Q

Diode

A

A diode is an electrical/electronic device made of semiconductor
materials which allow the electric current to flow through it in
only one direction.

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4
Q

Conduction band

A

The range of energy required to free an electron from an atom

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5
Q

Conduction band of Semiconductors

A

Inbetween electric conductors and electric insulators
Covalent Bonds

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6
Q

Instrinsic Semiconductor

A

(pure Semiconductor)
No holes or free electrons

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7
Q

Charge carriers

A

Free electrons and holes which are responsible for current flow thorugh a semiconductors

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8
Q

Current flow in intrinsic semiconductor

A

free electrons flow to the positive terminal, holes flow to the negative terminal

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9
Q

Doping

A

Add Phosphorus to create N-type Extrinsic semiconductor
Add Boron to create P-type Extrinsic semiconductor

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10
Q

Current flow in N-type semiconductor

A

Negative to Positive

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11
Q

Current flow in P-type semiconductor

A

Positive to Negative

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12
Q

P-N Junction

A

P and N type semiconductors placed togther will create a depletion region (barrier)

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13
Q

What happens if the negative terminal (–) is connected to the P-type semiconductor?

A

No current flow

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14
Q

What happens if the positive terminal (+) is connected to the P-type semiconductor?

A

Current flows; will release light if a light emmiting semiconductor is used

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15
Q

Composition of LED

A

a diode (P-N junction) made of a light emmiting material (GaN) with another light emmitting material sandwhiched in between (InGaN) and a ceramic substrate (Sapphire)

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16
Q

LED Chip Materials

A

III-V semiconductors
III = B, Al, Ga, In
V = N, P, As
Balga In Napals

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17
Q

Applications of LEDs

A

Table Lamps, Street Lights, Backlight for LCD monitors

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18
Q

OLED

A

Self illuminating, higher efficiency, thinner, brighter, flexible
Higher cost than LCD

19
Q

New LED Technologies

A

Mini LED : Source of Backlight
Micro LED : A new display

20
Q

Photocoltaic Effect

A

The photons from the sun light prompted electrons flowing from N-type semiconductor to the P-type semiconductor. → Electric current flow.

21
Q

Indium Tin Oxide (ITO)

A

Transparent ceramic electric conductor

22
Q

Solar Cell materials

A

P-N Junction of Si, tempered glass

23
Q

Types of Solar Cells

A

All Si P-N Juctions

  1. Single Crystal Si : 27% efficiency
  2. Polycrystaline Si : 20% efficiency
  3. amorphous (a-Si) : 10% efficiency
24
Q

Nanomaterials

A

Materials with at least one dimensionsmaller than 100 nanometer (nm)

25
MEMS
Micro-ElectoMechanical Systems are inertial sensors which detect: Acceleration Vibration Shock Tilt Rotation
26
Types of Nanotechnologies
Carbon Nanotube Electrode Quantum Corral: 14 nm diameter, qauntum confinement (traping of electrons)
27
Particle Sizes
cement dust > 4µm bacteria > virus carbon black < 100nm
28
Size dependent material properties of nanomaterials
Mechanical Optical Thermal Catalytic
29
Melting Temp of nanomaterials
decreases as particle size decreases
30
Modulus and Hardness of nanomaterials
Both decrease as size decreases
31
Color of nanomaterials
The smaller the particle, the more blue is absorbed and the redder it appears
32
Why are nanoparticle properties size dependent?
There are more atoms on the surface than the inside which means more atoms will be affected.
33
Carbon Nanotubes: Mechanical Properties
100 times stronger than steel same hardness as diamond but felxible
34
Carbon Nanotubes: Thermal Properties
Great conductor along axis (9x copper) great insulator across axis (0.4% copper)
35
Carbon Nanotubes: Electric Properties
Best electric conductor: can carry 1000x current of copper wires
36
Graphene
single layer used to make carbon nanotube best electric conductor
37
Magic angle of graphene
1.08 degree offset to create superconductor
38
Super thread
carbon nanotube fiber is the strongest and stiffest material on earth
39
CVD
Chemical Vapor Deposition for growing carbon nanotubes (CNT) on a silicon substrate
40
Colors on silicon wafers and butterflies
structural color
41
Apples latests bionic chip
5 nanometer process, 16 billion transistors
42
Modern Silicon IC tech
- Planar >= 28nm - FinFet <= 22nm - Gate-All-Around <= 3nm
43
Max # of particles per m^3 in Semiconductor Fab
35

MMET 206 (3 decks)

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