Chapter 1: Semiconductor Diodes

Semiconductors

are a special class of elements having a conductivity between that of a good conductor and that of an insulator.

Single crystal; Compound

2 Classes of Semiconductor

Germanium (Ge); Silicon (Si)

Examples of Single Crystal Semiconductor

Gallium Arsenide (GaAs); Cadmium Sulfide (CdS);
Gallium Nitride (GaN)
gallium arsenide phosphide (GaAsP)

Examples of Compound Semiconductors

Ge, Si, and GaAs

What are The three semiconductors used most frequently in the construction of electronic devices?

Germanium

What was diode made of in 1939?

Germanium (Ge)

Transistor is using what element in 1947?

Silicon (Si)

In1954 what was used in Transistor because it is less temperature sensitive and abundantly available?

GaAs

High speed transistor was using What element/compound in 1970 (which is 5 times faster compared to Si)?

Valence electrons

electrons in the outermost shell.

tetravalent

Atoms with four valence electrons

trivalent

Atoms with three valence electrons

pentavalent

Atoms with five valence electrons

Covalent bonding

sharing of electrons

Higher

The farther an electron is from the nucleus, the ___ is the energy state.

Free carriers

are free electrons due only to external causes such as applied electric fields established by voltage sources or potential difference

Five

n-Type materials are created by adding elements with how many valence electrons?

antimony, arsenic, and phosphorous.

Give examples of n-type materials:

Donor Atoms

What do you call the atom that are in n-type material?

Higher ; Less Energy

The free electrons due to the added atoms have _______ energy levels and require ______ to move to conduction band.

three

p-Type materials are created by adding atoms with thow many valence electrons?

Boron, Gallium; Indium

Give examples of p-type material:

Hole

The resulting vacancy is called a "____" represented by small circle or plus sign indicating absence of a negative charge.

Acceptor Atoms

What do you call the atoms I p-type materials?

electrons.

•The majority carriers in n-type materials are ____.

holes

The majority carriers in p-type materials are _____.

holes.

The minority carriers in n-type materials are __.

electrons.

The minority carriers in p-type materials are ____.

attracted

At the p-n junction, the excess conduction-band electrons on the n-type side are ____to the valence-band holes on the p-type side.

electron flow

The electrons in the n-type material migrate across the junction to the p-type material.

p-type; n-type

The electron migration results in a negative charge on the which side of the junction and a positive charge on the which side of the junction.

depletion region

The electron migration results in the formation of a ___ around the junction.

- No external voltage is applied: Vd =0V- No current is flowing: Id = 0A- Only a modest depletion region exist.

Characteristic of No Bias

Reverse Bias

External voltage is applied across the p-n junction in the opposite polarity of the p- and n-type materials.

- the reverse voltage causes the depletion region to widen.- the electrons in the n-type material are attracted toward the positive terminal of the voltage source. - The holes in the p-type material are attracted toward the negative terminal of the voltage source.

Characteristic of reverse Bias

Forward Bias

External voltage is applied across the p-n junction in the same polarity as the p- and n-type materials.

- The forward voltage causes the depletion region to narrow.- The electrons and holes are pushed toward the p-n junction.- The electrons and holes have sufficient energy to cross the p-n junction

Characteristic of forward Bias

Zener Region

is in the diode's reverse-bias region.

peak inverse voltage (PIV) or peak reverse voltage (PRV).

The maximum reverse voltage that won't take a diode into the zener region is called the

zener voltage (Vz)

The voltage that causes a diode to enter the zener region of operation is called the

Forward Bias Voltage

The point at which the diode changes from no-bias condition to forward-bias condition occurs when the electrons and holes are given sufficient energy to cross the p-n junction. This energy comes from the external voltage applied across the diode.

1.2V

The forward bias voltage required for gallium arsenide diode is __

0.7V

The forward bias voltage required for Silico Diode is ___.

0.3V

The forward bias voltage required for Germanium Diode is ___.

Directly

Temperature is ___ proportional to energy to the diode.

reduces; forward bias voltage

Temperature ____ the required ___for forward-bias conduction.

Increases; reverse current

Temperature ___ the amount of ______ in the reverse-bias condition.

Germanium Diodes

Which semiconductor material is more sensitive to temperature variations?

DC (Static) Resistance; AC (Dynamic) resistance; Average AC resistance

3 types of Ressistance

Zener Diode

is a type of diode that permits current not only in the forward direction like a normal diode, but also in the reverse direction if the voltage is larger than the breakdown voltage known as "Zener voltage" (VZ ).

Zener Voltage

Breakdown Voltage is also known as ___.

Regulator

Zener diode is used as ____.

1.8V - 200V

Common Zener voltages are between ____.

Light-Emitting Diode

LED stands for?

Photons; forward.

A LED emits ____ when it is _____ biased.

Amber AlInGaP 2.1
Blue GaN 5.0
Green GaP 2.2
Orange GaAsP 2.0
Red GaAsP 1.8
White GaN 4.1
Yellow AlInGaP 2.1

Light Emitting Diodes' Color, Construction, and Forward Voltage