Diode Characteristics and Properties Flashcards
What are diodes?
Semiconductors that allow the flow of electricity one way
To check forward resistance of a diode, the positive terminal lead of a multimeter should be connected to…
The anode
What gives the colour of an LED?
The active element
An atom with 5 electrons in its outer shell is part of P or N type material?
N type material
What is an SCR?
Silicon controlled rectifier (thyristor)
What are the properties of a thyristor?
- 3 terminal device used for switching
- turned on by a positive voltage at the gate
- silicon based
What component is used to turn AC to DV?
- Diode
- Thyristor
- Transistor
Diode
What type of diode gives off light photons when forward biased?
LED
To function, how much voltage does a germanium diode require?
0.3V forward biased
To function, how much voltage does a silicon diode require?
0.7V forward biased
What is a zener diode used for?
Voltage control.
It stabilises voltage at a predetermined level
When a diode is forward biased, what is the current flow due to?
The majority carriers (electrons and holes)
An atom with 5 electrons in its outer shell is part of what?
An N-type material.
It is pentavalent and will provide an extra free electron making the material N type.
Phosphor and Arsenic are examples
In a PN junction, what is the depletion region?
A depletion/lack of free electrons and holes in a vicinity of the junction.
It is reduced when the junction is forward biased
How is an SCR turned on?
A positive voltage at the gate
In a semiconductor junction diode, where are the electrons minority carriers?
Within the P region
If a rectifier circuit is designed to convert positive and negative cycles into DC output, what is the process called?
Full-wave rectification
Which type of diode (silicon or germanium) has the lower forward bias voltage?
Germanium diode
What are indium and aluminium used for in diodes?
They are a neutral semiconductor
How can the conductivity of an intrinsic semiconductor be improved?
By doping the materials
What are the electrodes of an SCR?
- gate
- anode
- cathode
How is an SCR switched off?
- Removing the source potential/reducing it below minimum holding current
- Reversing the current
A zener diode is reverse biased. When forward biased, what happens to a zener diode?
It will conduct like an ordinary rectifier diode.
When light falls onto a photo sensitive diode, it causes the resistance to…
Decrease
