Introduction to solar cells week 3 part A

Introduction to solar cells

week 3 part A

link to join this course https://www.coursera.org/learn/solar-cells

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Semiconductors and doping

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1.Question 1

A material is generally considered a semiconductor when...

The material exclusively consists of one element

EG is smaller than the thermal energy (3 eV)

Correct

That is correct

If the bandgap of a material is greater than the thermal energy it is considered an insulator.

EG is less than or equal to zero

1 / 1 point

2.Question 2

Which photons result in the highest energy conversion with minimum wasted energy?

Eph ≥ EG (photon energy equal to or larger than the bandgap)

Eph ≫ EG (photon energy much greater than the bandgap)

Eph = EG (photon energy equal to the bandgap)

Eph < EG (photon energy smaller than the bandgap)

Correct

That is correct

1 / 1 point

3.Question 3

Describe the difference between n-type and p-type doped semiconductors. Why are both needed for a solar cell?

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Correct

In an n-doped semiconductor the concentration of free electron is drastically increased and there is therefore a majority of negative charge carriers. A n-type silicon semiconductor is made by introducing for example Phosphorus, that has one additional valence electron as compared to silicon.

A p-doped semiconductor is created by introducing foreign atoms with less valence electrons (e.g. boron) than the silicon semiconductor. In the p-doped material hole conductance becomes possible.

With both types of doped silicon semiconductor it is possible to form a pn-junction. With the pn-junction a static electric field is formed allowing the charges to be seperated and current extracted from the solar cell.