P-N JUNCTIONS

A P-N junction is one of the most important semiconductor devices with applications ranging from rectifiers to solar cells. It is also an important part of more complex devices such as transistors. In this chapter you get to play with an ideal abrupt P-N Junction.

P-N Junction

Imagine we magically connect P-type and N-type pieces of Si together. Let's see what happens.

Doping Concentration (per cm3):

5x1013

1014

After reaching equilibrium, do you see any electrons going from the N-side to the Pside? What do they have in common? What happens if an electron-hole pair is generated in the middle (depletion region)?

Apply Voltage

Let's apply a positive or negative voltage across this device and see what happens.

Doping Concentration (per cm3):

5x1013

1014

Applied Voltage (V)

-1.6

-1.2

-0.8

-0.4

0

0.4

Minority Carrier Concentration

Minority carrier concentration changes by many orders of magnitude depending on the applied voltage. Play with the applied voltage and see if you can qualitatively explain the trends you observe.

Doping Concentration (per cm3):

5x1013

1014

Applied Voltage (V)

-1.6

-1.2

-0.8

-0.4

0

0.4