A solar cell works on the photovoltaic effect, where it converts light energy (photons) into electrical energy. When light hits the semiconductor material, it excites electrons, generating an electric current.
What is the role of the anti-reflective coating on a solar cell?
A Increase efficiency
B Enhance current
C Increase voltage
D Absorb light
The anti-reflective coating on a solar cell helps reduce the reflection of light, allowing more light to be absorbed into the semiconductor material. This increases the efficiency of the solar cell by capturing more energy from sunlight.
What is the function of the emitter in a solar cell?
A Absorb photons
B Collect electrons
C Reflect light
D Generate voltage
In a solar cell, the emitter is the region that collects the electrons generated by the absorption of photons. These electrons then move toward the external circuit to generate electric current.
What material is most commonly used for solar cells?
A Silicon
B Copper
C Gallium Arsenide
D Aluminum
Silicon is the most commonly used material for solar cells due to its abundance, cost-effectiveness, and suitable semiconductor properties. It can efficiently convert sunlight into electricity in both monocrystalline and polycrystalline forms.
What is the primary function of a photodiode in optoelectronics?
A Light emission
B Voltage regulation
C Signal amplification
D Light detection
A photodiode is designed to detect light and convert it into an electrical signal. When photons strike the photodiode, they generate electron hole pairs, producing a current proportional to the light intensity.
How does a phototransistor differ from a photodiode?
A Amplifies signal
B Converts light to voltage
C Generates power
D Requires no current
A phototransistor, unlike a photodiode, can amplify the current generated by the incident light. It works by using a small current to control a larger current, which makes it more sensitive and useful for optical signal amplification.
What is the purpose of doping in semiconductor IC fabrication?
A Increase resistance
B Decrease voltage
C Control carrier concentration
D Control temperature
Doping in semiconductor IC fabrication involves adding impurities to control the carrier concentration (electrons or holes) in the material. This is crucial for forming p type or n type semiconductors and achieving desired electrical properties.
What is the process of photolithography used for in IC fabrication?
A Patterning
B Welding
C Doping
D Polishing
Photolithography is used in semiconductor IC fabrication to create patterns on the semiconductor surface. It involves exposing a light sensitive material (photoresist) to ultraviolet light through a mask, forming intricate circuit designs on the chip.
What is the primary characteristic of a p n junction in semiconductor devices?
A High resistance
B Low resistance
C Rectification
D Amplification
A p n junction allows current to flow in one direction only, a property known as rectification. This is essential in devices like diodes, where the junction blocks current under reverse bias and allows it to flow under forward bias.
What is the main purpose of a semiconductor diode in an electric circuit?
A Signal modulation
B Signal amplification
C Power regulation
D Current rectification
A semiconductor diode is used to rectify current, allowing current to flow in one direction and blocking it in the reverse direction. This makes it essential for converting AC to DC in power supplies.
What is the role of the collector in a Bipolar Junction Transistor (BJT)?
A Control current flow
B Collect charge carriers
C Emit charge carriers
D Amplify signal
In a BJT, the collector is responsible for collecting the charge carriers (electrons or holes) that flow through the base from the emitter. This allows the transistor to amplify signals and control larger currents.
What is the energy band gap of silicon?
A 0.1 eV
B 2.5 eV
C 1.1 eV
D 0.5 eV
Silicon has an energy band gap of 1.1 eV. This moderate band gap makes silicon suitable for a wide range of semiconductor devices, from transistors to diodes, and allows it to function efficiently in various electronic applications.
What is a major disadvantage of using Gallium Arsenide (GaAs) in semiconductor devices?
A High cost
B Low efficiency
C High thermal conductivity
D Low speed
While Gallium Arsenide (GaAs) has excellent properties for high speed devices, its high cost compared to silicon limits its widespread use in commercial applications. It is typically used in high performance or specialized devices like microwave amplifiers and solar cells.
What is the role of the base in a BJT?
A Emit charge carriers
B Collect charge carriers
C Amplify signal
D Control current flow
The base of a BJT controls the flow of current between the collector and emitter. A small base current allows a much larger current to flow from the collector to the emitter, enabling the transistor to function as an amplifier.
What does the term “band gap” refer to in a semiconductor?
A Current flow
B Difference in energy levels
C Voltage drop
D Doping level
The band gap in a semiconductor is the energy difference between the valence band and the conduction band. It determines the ability of electrons to move from the valence band to the conduction band, influencing the material’s conductivity.