Specially designed p-n junctions are semiconductor devices engineered for specific applications beyond standard rectification. These include light-emitting diodes (LEDs), photodiodes, and photovoltaic cells, each utilizing the unique properties of p-n junctions to perform distinct functions. LEDs emit visible light when an electron recombines with a hole in the forward-biased junction, making them ideal for lighting and display technologies. Photodiodes are designed to convert light into electrical current, serving as sensors in various applications, including cameras and optical communication. Photovoltaic cells, commonly used in solar panels, convert sunlight directly into electricity through the photovoltaic effect. These specialized p-n junctions leverage the fundamental principles of semiconductor physics to enable a wide range of modern electronic and optoelectronic devices
What are specially designed p-n junctions?
Specially designed p-n junctions are semiconductor devices engineered for specific applications, such as light-emitting diodes (LEDs), photodiodes, and photovoltaic cells.
What is the function of a light-emitting diode (LED)?
An LED emits visible light when an electron recombines with a hole in the forward-biased p-n junction, making it useful for lighting and display applications.
How does a photodiode operate?
A photodiode operates by converting light into electrical current; when light photons strike the p-n junction, they generate electron-hole pairs, increasing the reverse current.
What is the primary application of photovoltaic cells?
Photovoltaic cells are primarily used to convert sunlight into electricity, making them essential components in solar panels.
What materials are commonly used to make LEDs?
LEDs are typically made from semiconductor materials such as gallium arsenide and gallium arsenide phosphide.
What is the primary function of a light-emitting diode (LED)?
a) To detect light
b) To emit visible light
c) To convert AC to DC
d) To store energy
Answer: b) To emit visible light
Which semiconductor material is commonly used in the construction of LEDs?
a) Silicon
b) Gallium arsenide
c) Germanium
d) Copper
Answer: b) Gallium arsenide
What is the main application of a photodiode?
a) To emit light
b) To convert light into electrical current
c) To rectify AC voltage
d) To amplify signals
Answer: b) To convert light into electrical current
In which mode is a photodiode typically operated for light detection?
a) Forward bias
b) Reverse bias
c) Zero bias
d) Direct bias
Answer: b) Reverse bias
What phenomenon allows photovoltaic cells to generate electricity?
a) Electroluminescence
b) Photovoltaic effect
c) Thermoelectric effect
d) Piezoelectric effect
Answer: b) Photovoltaic effect