MCQ Quiz On Introduction To Semiconductors

Silicon is the most commonly used semiconductor among the given substances. Semiconductors are materials that have properties between those of conductors and insulators, allowing them to control the flow of electrical current. Silicon is widely used in the electronics industry due to its abundance, stability, and versatility in conducting electricity. It is a fundamental component in the production of integrated circuits, transistors, and other electronic devices. Germanium and Galena were also used as semiconductors in the past, but silicon's superior properties and availability have made it the dominant choice in modern technology. Copper, on the other hand, is a good conductor of electricity but not a semiconductor.

GaAs refers to gallium arsenide, which is a compound. Compounds are substances composed of two or more elements chemically bonded together. In this case, gallium (Ga) and arsenic (As) are combined to form gallium arsenide. Therefore, the correct answer is A compound.

When a P-N junction is reverse-biased, the voltage applied across the junction is in the opposite direction of the normal flow of current. In this case, the junction is reverse-biased at a voltage less than the avalanche voltage, which means that the voltage applied is not high enough to cause the avalanche breakdown and allow current to flow through the junction. Therefore, the junction does not conduct even though a voltage is applied.

In P-type material, the majority carriers are the positively charged holes, which are created due to the presence of acceptor impurities. The minority carriers, on the other hand, are the electrons, which are present in much smaller quantities compared to the holes. Therefore, the correct answer is "The minority carriers."

Semiconductor devices have many advantages over vacuum tubes, such as smaller size, lower working voltage, and lighter weight. However, one advantage that vacuum tubes have over semiconductor devices is their ability to withstand high voltage spikes. Unlike semiconductor devices, which can be easily damaged by high voltage spikes, vacuum tubes are more resilient in this regard.

A hole can be considered to have a charge of +1 unit because it is essentially an absence of an electron in the valence band of a semiconductor. When an electron leaves the valence band, it leaves behind a positive charge in the form of a hole. This hole can move through the crystal lattice and behave as if it were a positively charged particle. Therefore, a hole is considered to have a charge of +1 unit.

Doping in semiconductors involves intentionally adding impurities to alter the electrical properties of the material. By introducing impurities, the semiconductor can exhibit specific properties such as increased conductivity or the ability to emit light. This process allows for the customization of semiconductor materials to suit specific applications in electronics and optoelectronics.

Adding a donor impurity to a semiconductor material makes it N-type. In N-type semiconductors, the donor impurity atoms have extra valence electrons compared to the host material, which results in the creation of excess free electrons. These free electrons are responsible for the conductivity of the N-type material.

Holes flow the opposite way from electrons because they have an opposite electric charge. In a semiconductor material, when an electron leaves its position, it leaves behind a positively charged hole. This hole behaves as a positive charge carrier and can move through the material in the opposite direction of the negatively charged electrons. This movement of holes contributes to the flow of current in the opposite direction of the flow of electrons.

The term semiconductor arises from the variable conductive properties of some materials. Semiconductors are materials that have electrical conductivity between that of a conductor and an insulator. They can be controlled to conduct or not conduct electricity, making them ideal for use in electronic devices such as transistors and diodes. The ability of semiconductors to vary their conductivity is due to the presence of energy bands and the movement of electrons within these bands. This property allows semiconductors to be used in a wide range of applications in the field of electronics.

Germanium allows the lowest forward voltage drop in a diode compared to the other materials listed. This is because Germanium has a lower bandgap energy than Silicon, Copper, and Selenium. A lower bandgap energy means that Germanium requires less energy to allow current to flow in the forward direction, resulting in a lower forward voltage drop.

When a P-N junction is forward-biased, conduction will not occur unless the applied voltage exceeds the forward break-over voltage. This is because the forward break-over voltage is the minimum voltage required to overcome the potential barrier at the junction and allow current to flow. If the applied voltage is less than the forward break-over voltage, the potential barrier will not be overcome and conduction will not occur. Therefore, the applied voltage must exceed the forward break-over voltage for conduction to take place.

MOS devices can be damaged by electrostatic discharges. Electrostatic discharges occur when there is a sudden flow of electricity between two objects with different electric potentials. This discharge can cause a high voltage spike that can damage the delicate components of MOS devices. Therefore, it is important to handle and protect MOS devices from electrostatic discharges to ensure their proper functioning and longevity.

Selenium works especially well in photocells because it is a semiconductor material that exhibits photoconductivity. When light is incident on selenium, it excites the electrons in the material, allowing them to move more freely and conduct electricity. This property makes selenium a suitable material for converting light energy into electrical energy in photocells.

When an acceptor impurity is added to a material, it creates holes in the crystal lattice. These holes act as positive charge carriers, resulting in a P-type material. Current flows mainly in the form of these holes, which have a positive electric charge. However, adding an acceptor impurity does not result in the substance acquiring an electron surplus. Instead, it creates a deficit of electrons, leading to the formation of holes.

When a P-N junction acts as a voltage regulator, it is designed to maintain a constant output voltage regardless of changes in input voltage or load. In this mode of operation, the P-N junction is biased in reverse breakdown region, where the avalanche voltage is routinely exceeded. This allows the P-N junction to regulate the voltage by controlling the current flow through it, ensuring a stable output voltage. Therefore, the correct answer is voltage regulator.

A CMOS integrated circuit is known for its low power consumption. This is because CMOS technology uses complementary pairs of MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) that consume power only when they switch states. When one transistor is on, the other is off, resulting in very low power consumption compared to other types of integrated circuits. Therefore, a CMOS integrated circuit requires very little power to function.

The correct answer is "Plus to minus." This refers to the movement of charge carriers, specifically holes, in a circuit. In a conventional current flow, positive charges move from the positive terminal (plus) to the negative terminal (minus) of a power source. Therefore, holes, which are positively charged, also move in the same direction, from the region of higher potential (plus) to the region of lower potential (minus).

The phase of an applied AC signal does not affect the junction capacitance of a diode. The junction capacitance is primarily determined by the physical characteristics of the diode, such as the cross-sectional area of the P-N junction and the width of the depletion region. The reverse-bias voltage also affects the junction capacitance, as it changes the width of the depletion region. However, the phase of an applied AC signal does not have any direct impact on the junction capacitance.

When the reverse bias exceeds the avalanche voltage in a P-N junction, it creates a high electric field across the junction. This electric field causes the electrons in the valence band to gain enough energy to break free from the covalent bonds and become free electrons. These free electrons can then move across the junction, resulting in current flow. Therefore, the correct answer is that the junction will conduct current.