Semiconductors and Their Properties

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Questions and Answers

Which material is classified as a compound semiconductor?

Gallium Arsenide (correct)

Copper

Germanium

Silicon

Which statement about the resistivity of semiconductors is accurate?

They have lower resistivity than conductors.

They have resistivity ranges from 10−12 to 10−8 Ω⋅m.

They exhibit very high resistivity compared to insulators.

Their resistivity ranges from 10−6 to 10^6 Ω⋅m. (correct)

What describes the conductivity of insulators compared to semiconductors?

Insulators allow current to flow easily, similar to semiconductors.

Insulators have higher conductivity than semiconductors.

Insulators have a negligible number of free electrons. (correct)

Insulators have moderate conductivity and low resistivity.

Which of the following materials has the highest electrical conductivity?

Copper Signup and view all the answers

What is the primary function of semiconductor devices?

To control the flow of current. Signup and view all the answers

What characterizes the conduction and valence bands of insulators?

Conduction Band has $E_g$ Signup and view all the answers

Which statement about intrinsic semiconductors is correct?

Holes concentration $n_h$ is equivalent to free electron concentration $n_e$. Signup and view all the answers

How does intrinsic carrier concentration $n_i$ behave with temperature according to the relationship provided?

$n_i$ increases exponentially with temperature. Signup and view all the answers

In an intrinsic semiconductor, which relationship holds true for $n_e$, the free electron concentration?

$n_e$ is equal to $n_h$ for all types of semiconductors. Signup and view all the answers

In an N-type semiconductor, which statement correctly describes the role of the added impurities?

They add pentavalent elements that contribute an extra electron. Signup and view all the answers

What is the relationship between the concentration of majority charge carriers and the intrinsic carrier concentration in N-type semiconductors?

The product of majority and minority carrier concentrations is equal to the square of intrinsic concentration. Signup and view all the answers

What happens to carrier mobility when temperature increases in semiconductors?

Carrier mobility typically increases, improving conductivity. Signup and view all the answers

In the energy band structure of a pure semiconductor, where is the forbidden gap located?

Between the conduction band and the valence band. Signup and view all the answers

Which equation correctly represents the conductivity in terms of charge carrier mobilities?

$\sigma = (N_e u_e + N_h u_h)e$ Signup and view all the answers

What is the implication of having a concentration of impurities of 1 per $10^{15}$ atoms in a semiconductor?

It creates a significant increase in majority charge carriers. Signup and view all the answers

In an n-type semiconductor, what can be said about the relationship between the concentration of donor atoms and free electrons?

The concentration of donor atoms is nearly equal to that of free electrons. Signup and view all the answers

What characterizes the energy level related to acceptor impurities in a p-type semiconductor?

It is located just above the valence band. Signup and view all the answers

Which equation accurately represents the relationship of charge carrier concentrations in a p-type semiconductor?

Nh × Ne = Ni^2 Signup and view all the answers

What is the role of trivalent atoms in the context of p-type semiconductors?

They provide additional vacancies that act as charge carriers. Signup and view all the answers

In the energy band diagram, where do the donor levels appear in an n-type semiconductor?

Within the forbidden gap near the conduction band. Signup and view all the answers

Which characteristic differentiates a semiconductor from a conductor?

A small energy gap between valence and conduction bands Signup and view all the answers

What enables electrons in semiconductors to transition from the valence band to the conduction band?

Sufficient external energy Signup and view all the answers

In the context of energy levels in silicon, which statement is true regarding intrinsic semiconductors?

Their conduction relies solely on temperature increase. Signup and view all the answers

Which of the following best describes the charge carriers in silicon when it behaves as a semiconductor?

Both electrons and holes contribute to conduction Signup and view all the answers

Compared to conductors, what type of band structure do semiconductors possess?

Non-overlapping valence and conduction bands Signup and view all the answers

What occurs at the P-N junction during the initial diffusion process?

Holes move from P to N and electrons from N to P. Signup and view all the answers

What is the role of the depletion region in a P-N junction?

It forms a barrier against further diffusion. Signup and view all the answers

What is the effect of forward biasing on the depletion region?

It narrows the depletion region. Signup and view all the answers

In terms of energy, what does the equation 'V0 = Ein / d' represent?

The potential barrier created by the depletion region. Signup and view all the answers

Which statement best describes the electric field within the depletion region?

It exists due to charge imbalance created by diffusion. Signup and view all the answers

What happens to the potential barrier during reverse biasing of a P-N junction?

It increases. Signup and view all the answers

In reverse biasing, which carriers move toward the junction?

Minority carriers from both sides. Signup and view all the answers

In the context of a P-N junction, what occurs during forward biasing?

Holes from the P-type material and electrons from the N-type material move towards the junction. Signup and view all the answers

Which equation correctly describes the relationship between the total energy in a forward-biased P-N junction?

Enen = Eex + Ein Signup and view all the answers

What characterizes the current in a reverse-biased P-N junction?

It is negligible and due to minority carriers. Signup and view all the answers

What happens to the width of the depletion region when a P-N junction is forward biased?

The width of the depletion region decreases. Signup and view all the answers

Which statement accurately describes the resistance of a reverse-biased diode?

Resistance is very high, allowing negligible current. Signup and view all the answers

In the context of a reverse-biased P-N junction, which equation represents the relationship of energies?

$E_{nen} = E_{ex} + E_{in}$ Signup and view all the answers

What is the result of connecting a P-N junction to an external power source?

It creates a condition for either forward or reverse biasing. Signup and view all the answers

What is the balance condition for free electron and hole concentrations in an intrinsic semiconductor?

$n_e imes p_h = n_i^2$ Signup and view all the answers

Which characteristic distinguishes an ideal diode from a non-ideal diode when forward biased?

An ideal diode behaves like a short circuit. Signup and view all the answers

What will happen to the hole concentration if the intrinsic carrier concentration in a semiconductor is increased?

The hole concentration will increase. Signup and view all the answers

If the concentration of Arsenic in an N-type semiconductor is significantly higher than the intrinsic carrier concentration, what is the expected outcome for the free hole concentration?

It will approach zero. Signup and view all the answers

What impact does the addition of boron impurities have on the free electron concentration in a silicon semiconductor?

It decreases the free electron concentration. Signup and view all the answers

What significance does the knee voltage (Vk) have in the I-V characteristic of a forward-biased P-N junction?

It marks the voltage at which current increases dramatically. Signup and view all the answers

Which statement correctly describes the relationship of dynamic resistance in a forward-biased P-N junction?

Dynamic resistance can be categorized as R1 > R2 > R3 based on increasing voltage. Signup and view all the answers

What is the primary cause of current generation in a forward-biased P-N junction?

Diffusion of majority charge carriers Signup and view all the answers

Which characteristic best defines the behavior of a forward-biased P-N junction compared to Ohm's law?

It behaves in a non-linear fashion and does not adhere to Ohm's law. Signup and view all the answers

How does increasing the voltage affect the current in a forward-biased P-N junction after reaching the knee voltage?

Current increases rapidly as voltage continues to rise. Signup and view all the answers

Study Notes

Semiconductor Devices used to control the flow of current are there amount is known as conductors.

Types of material and bases of conductivity

(😀) Conductors - large number of the electrons so they have very high electric conductivity. As the temperature increases the resistivity increases and conductivity decreases.

(😃) Semiconductors - they have a very less amount of electrons and comparison to the conductors with smaller conductivity As the temperature increases the conductivity increasing the resistivity decreases

(😄) Insulators - Negligible amount of electrons hence, poor conductor of electricity Resistivity (Ω-m) 🌺Conductors. 10^8 to 10^12 🌺Semiconductors. 10^[-6] to 10^6 🌺Insulators. 10^11 to 10 ^17

Types of semiconductors

(1) Elemental - silicon(Si), Germanium (Ge) (2) Compound - (a) Inorganic- CdS , InP , GnAs etc (b) Organic - pthalycine , anthracene

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Description

This quiz covers fundamental concepts related to semiconductors, including their classification, conductivity, and the behavior of intrinsic and extrinsic materials. Test your understanding of key terms and principles surrounding semiconductor physics.