Diodes

A zener diode only works in (reverse/forward) bias

reverse

A zener diode is used to intentionally conduct ____ current. Also known as a _____ _____.

reverse voltage regulator

A zener diode resembles that of a conventional diode with a slight alteration to the cathode element. What is it?

A flag at each end of the cathode

Define diode

A unidirectional device that will allow current to flow in only one didection

A diode contains n and p materials separated by a junction called the

PN junction

***Breakdown voltage is typically between

-50 - 100V

What is the turn on voltage for germanium?

0.2 - 0.3VT

What is the turn on voltage for silicon?

0.6 - 0.7VT

4 diode uses and what they mean

1. Rectifiers : used to convert ac into dc 2. Switches : opens or closes a circuit under the proper conditions 3. Limiter: limit the amplitude of input signals at the output of the current 4. Clampers: used to add dc voltage level to an ac input signal

What is doping?

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

In schematics, the Anode is represented by an _____ and is the ____ side of the diode

Arrowhead Positive

Voltage is also known as ____ and is directional

Bias

Electron flow is always from the ___ to the ___.

Cathode Anode

Diode Reference designator

D or CR

____ flow toward the positive charge

Electrons

______ are the minority carrier in P type material

Electrons

What are the 2 most commonly used semiconductor materials?

Germanium and silicone

____ are the majority carriers in P type material

Holes

____ are the minority carriers in N type marerisl

Holes

____ flow toward the negative charge

Holes

Semiconductors offer less resistance than —-, but more than —-.

Insulators Conductors

Three most common types of diodes

Junction Zener LED

Electrons are the majority carriers in ___ type material

N type

The cathode of a diode represents the ___ material and has an increase of ____ _____

N type Free electrons

The anode represents the ___ type material and has an increased number of ____.

P type Holes

In a reverse biased junction, negative potential is applied to the ____. Positive potential is applied to the ___.

P-material (anode) N-material (cathode)

In schematics, the cathode is represented by a _____ _____ and is the _____ side of the diode.

Single line Negative

T/F There are no mobile carriers in the depletion region

T

In a reverse biased junction, the source now (aids/inhibits) barrier potential. The junction has a very (high/low) resistance to current flow.

aids high

The purpose of a junction diode is to

allow current flow in one direction only

In forward bias, the positive potential is applied to the _____ and the negative potential is applied to the ____.

anode (p-material) cathode (n-material)

Forward bias must have a potential large enough to overcome ____ ____

barrier potential

____ is the application of a voltage across a PN junction that aids (forward bias) or opposes (negative bias) current flow

bias

Current flow is a function of ____. Increasing forward bias voltage increases _____.

bias current

___ occurs when there is excessive reverse bias voltage and causes the depletion region to break apart, which cause a very large flow of current.

breakdown (A diode will be damaged due to heat generated by the large amount of current)

An LED schematic symbol looks like a junction diode, except that it has two arrows pointing outward from the ____

cathode (bar)

When forward biased and above VT, the junction diode acts like a ___ ___ allowing current to flow freely

closed switch

A forward biased diode is said to be "___" when current flows through it.

conducting

Forward bias ___ the width of the depletion regions

decreases

The recombination area is called the ___ ___

depletion region

P material loses holes near the junction through recombination with ___

electrons

N material loses electrons near the junction through recombination with ____

holes

in reverse bias, the depletion region is (increased / decreased)

increased

Reverse biased is when bias voltage is ____ to reach VT or bias source polarities are reversed from forward bias

insufficient

A zener diode placed forward bias in a circuit operates like a ____ diode.

junction

When P and N material are initially joined together, electrons from N-material diffuse to ____ concentration across the junction into the P material and holes from the P material diffuse across the junction into the ___ _____

lower N material

If voltage applied to a circuit falls below breakdown voltage, the zener diode will revert to acting like an ___ ____.

open switch

When reversed biased or below VT the junction diode acts like an ____ ____, preventing current flow

open switch

An LED emits light when (+ / -) voltage passes through it.

positive

Forward bias offers (very little / a lot) of resistance to current flow

very little