The Manga Guide to Electricity

If an element with

five valence electrons,

like phosphorus,

is mixed in with a

siliconcrystal...

...the phosphorus

and silicon bond,

and one valence

electron escapes.

It becomes a

fr electron,

right?

Fr electron

That's right!

This causes the

electricalconductivity

of this semiconductor

toincrease.

This semiconductor

is caed an n-type

semiconductor

because the electron,

which has a negative

electrical property,

becomes a caier

ofelectricity.

What's

this n ?

...What's

wrong?

The n stands

for negative.

Ah...!

Negative

Silicon

Phosphorus

Silicon

Silicon

Phosphorus

Sigh...

166 Chapter 5 How Can You Conveniently Use Electricity?

Now, let's say we

mixed in a lile of the

element boron, which

has thr valence

electrons.

The boron and silicon

bond, but there is an

empty seat left in the

space that doesn't have

an electron.

Empty seat?

This empty

seat iscaed

a hole.

Holes are places

electrons are

vacant in covalent

bonds.

You can think

ofthe hole as

a fr electron

with a positive

charge.

Okay...

Boron

Hole

Hole

Drift

Drift

Hole

Hole

Semiconductors 167

Therefore,

electrical

conductivity also

increases for this

semiconductor.

This kind of

semiconductor is caed

a p-type semiconductor

because the hole, which

has a positive electrical

property, becomes a

caier of electricity.

What's the p

stand for?

What's the

oosite of

negative?

Oosite...

!!

The p stands for

positive, right?

Right!

The substance

formed by mixing

an element such

as phosphorus or

boron into a pure

silicon crystal is

caed an extrinsic

semiconductor.

I get it!

Electricity

n-type P-type

Extrinsic semiconductor

168 Chapter 5 How Can You Conveniently Use Electricity?