Diodes

Diode Reference designator

(D) or (CR)

P-Material loses holes near the junction through what?

Recombination with electrons

N-Material loses electrons near the junction through what?

Recombination with holes

Anode

represented by an arrowhead and is the positive side of the diode.

Zener diode Identification

resembles that of a conventional diode with a slight alteration to the cathode element. (A "Flag" at each end of the cathode)

A Zener diode MUST be placed

reverse bias in a circuit to operate as a voltage regulator

Current carriers in P-type material.

Holes are the majority and Electrons are minority

Current carriers in the N-type material

Holes are the minority and Electrons are the majority

Limiter

Limit the amplitude of input signals at the output of the circuit.

What is a Diode?

A uni-directional device that will allow current to flow in only one direction.

The anode represents what?

P-type material and has an increased number of holes.

germanium requires

.2V -. 3V

Silicon requires

.6V -.7V

What is Bias?

1. Energy applied across the semiconductor in the form of a voltage 2. directs the flow of holes and electrons.

Forward biased junction

1. Offers very little resistance to current flow 2. Decreases the width of the depletion region. 3. Must have a potential large enough to overcome barrier potential

What is barrier potential?

A buildup of positive and negative ions in the junction area which opposes any further diffusion or recombination and opposes current flow across the junction until some external force is applied.

What is a PN Junction?

A diode contains N and P materials joined together, separated by a junction.

What is doping?

A process of adding impurities (in controlled amounts) to semiconductor material to increase its conductivity.

What is the purpose of a junction diode?

Allow current flow in one direction only.

Electron flow is always from the what?

Cathode to the Anode.

The cathode of a diode represents what?

N-type material and has an increase of free electrons

Switches

Opens or closes a circuit under the proper conditions.

When are Germanium and silicon most commonly used?

Semiconductor materials.

When P and N material are initially joined together

electrons from N-material diffuse to lower concentration across the junction into the P-material and holes from the P-material diffuse across the junction into the N-material.

What is deletion region?

This narrow area of recombination

Clampers

Used to add a DC voltage level to an AC input signal.

Rectifiers

Used to convert AC into pulsating DC.

What is a LED?

another special type of diode that emits light when current passes through it.

Holes and electrons are present in both type materials_______

but N-type has more electrons than holes and P-type has more holes than electrons.

Cathode

indicated by a single line (bar) just touching the tip of the arrowhead and represents the negative side of the diode.

A Zener diode placed forward bias in a circuit operates like a

junction diode

What are the most common types of diodes?

junction, Zener, and LED (Light Emitting Diode).

Holes flow towards what?

negative charge.

Electrons flow towards what?

positive charge.