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Flashcards in Semi-Conductor Questions Deck (27):
1

How do you estimate the concentration of electrons and holes in a p-type semiconductor? 

nrefers to the concentration of electrons

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2

How do you calculate the concentration of electrons and holes in an n-type semiconductor? 

pn refers to hole concentration

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3

What Hall voltage do you expect for a positive majority carrier ? 

And negative majority carrier? 

Positive 

Negative

4

What is the Hall coefficient ? 

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5

What equation would you use to calculate the built-in voltage of a silicon PN junction?

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6

The equation that relates the depletion region width (lengths) to the concentration? 

What does it tell us? 

Tells us that depletion regions can only be symmetric if the donor and acceptor concentration are equal.

xn region of the donor , n for negative 

x region of the accepto, p for positive  

 

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7

What does a reverse bias in a pn junction do to the built-in voltage? 

It increases the built in voltage and increases the barrier potential. 

8

Graphical representation of the effect a reverse and forward bias has on the diffusion current. 

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9

The equation for Itotal through a pn junction ? 

What is this equation essentially? 

The equation for current through a diode. 

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10

What do you call the terminal of a diode where the current flows into?

anode(+)

11

What do you call the terminal of a diode where current flows out of ?

cathode (-)

 

remember current flows from positive to negative.

12

What is the equation for current density? 

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13

What does a direct bandgap semiconductor emit? 

Through radiative recombination it releases photons.

14

The equation for the energy of a photon? 

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15

If you have the band gap energy, what equation do you use to determine the wavelength? 

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16

The equation for current through solar cell ?

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17

Sketch the IV characteristic of a solar cell in the dark and under light.

Include all details. 

Where is the region of interest for extracting solar power?

Include Iphoto and V oc  

and the region for extracting power 

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18

What is the equation for the short circuit current for a solar cell ? 

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19

What does it mean that the IV(power) characteristic for a solar cell is in the negative quadrant? 

If it's negative it means that power is being extracted from the device. 

20

The easy way of determining maximum power rectangle of a solar cell? 

take the product of Isc and V oc  

Then multiply by 0.8. 

21

The equation for the oxide capacitance of a MOSFET? 

Where epsilon is the numerator 

and 

tox thickness of oxide layer

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22

The equation for overdrive voltage? 

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23

State which of the materials given in Table 7.1 would be suitable for use in an LED, and why.

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LEDs work when the PN junction is in the forward bias. 

LEDs are based on electron-hole recombination. 

The electromagnetic energy they release is equal to the band gap energy.

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24

For each number, name the region and suggest a specific material (including dopants) from which it can be made. 

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25

The equation to calculate the concentration of electrons in the conduction band. 

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26

What is the unit for electron or hole concentration?

cm-3

27