Diodes Flashcards
Approximate thickness of depletion layer?
10^-6 m
Or
1 micrometer
Potential barrier (Vb) for Germanium diode
0.3V
Potential barrier for silicon diode
0.7V
Barrier electric field is of the order?
10^5 Vm-1
For forward biasing forward current is of the order
mA
For reverse biasing the order of reverse current is
MicroAmpere
What is the Richardson-Dushman Equation for half wave rectifier?
J= A x t^2 x e^(W/kT)
Where:
W- work function
k- Boltzmann’s constant
A-constant for pure metals= 60 A/cm2
Child Langmuir Law
For a space charge limited current :-
L~ (V)^3/2
Vrms =?
Vpeak/2
Vdc =? (For half wave rectifier)
Vpeak/||
Vpeak =?
2xVrms = ||xVdc
Vdc for full wave rectifier ?
2xVpeak/||
Ripple?
AC components present in rectifier’s outputs
Ripple factor (r)?
Measurement of AC components in a rectifier’s output
Ripple factor(r) for half wave rectifier
1.21
Ripple factor for full wave rectifier
0.48
In reverse biased mode how does the LED work
It works like a normal diode
LED’s light emitting intensity is
Directly Proportional to forward current
Photodiode materials?
Cadmium Sulphide (CdS) Serilium (Se) Zinc Sulphide (ZnS)
For a photodiode Energy of incident light photon must be
Greater than the forbidden gap energy
In Solar cells one of the semiconductors is made extremely small
So that solar radiation falling on it passes to the junction without any absorption
Popularly used solar cells?
Nickel-Cadmium (Ni-Cd)cell Lead Sulphide(PbS) cell
Width of depletion zone is
Dependant of dopant densities
On forward biasing a p-n junction
Number of donors in n-side increase
On forward biasing the width of depletion layer
Decreases
On reverse biasing the width of depletion layer
Increases
Photodiode is
Reverse biased and heavily doped
LED is
Forward biased
Materials used to make LED diodes
GaAs
GaP
