10 Devices

Question 1

what are 3 semiconductor devices

Answer 1

• pn junction
• LEDs
• Transistors

Question 2

what is a pn-junction

Answer 2

• connect p and n dopped semiconductors
• e in n migrate to p, shift E of bands

Question 3

pn junctions: As electrons are
added to a SC, the band energy ______.
Conversely, as electrons are removed from a SC,
the band energy ______.

Answer 3

increases, decreases

Question 4

n and p brought together their fermi levels?

Answer 4

align

Question 5

What is a depletion layer?

Answer 5

• as e/ h move leave behind donor ions close to junction
• region where ionized atoms exist

Question 6

pn junction under no bias

Answer 6

• as e migrate E p type semiconductor increases, stops when femi levels same

Question 7

Bias

Answer 7

Forward: + (h) at P, - (e) at n, smaller diff b/w CB and VB
Reverse: opp

Question 8

Under forward bias the potential energy barrier
at the depletion region _________.
Under
reverse bias the potential energy barrier at the
depletion region _______.

Answer 8

Decreases, increases

Question 9

LEDs

Answer 9

pn junction under forward bias

• e and h migrate to depletion layer and recombine to generate photon

Question 10

how to tune LED colour

Answer 10

• change material
• change band structure (add impurities)
• add filter
• build device with red, green, blue LEDs and control intensity

Question 11

MOSFET parts

Answer 11

i) Source, ii) Drain, iii) Gate, iv) p-region, v) n-region, vi) Metal, vii) oxide