Semiconductors and Their Properties

<p>Copper (D)</p> Signup and view all the answers

<p>To control the flow of current. (C)</p> Signup and view all the answers

<p>Conduction Band has $E_g$ (C)</p> Signup and view all the answers

<p>Holes concentration $n_h$ is equivalent to free electron concentration $n_e$. (B)</p> Signup and view all the answers

<p>$n_i$ increases exponentially with temperature. (B)</p> Signup and view all the answers

<p>$n_e$ is equal to $n_h$ for all types of semiconductors. (D)</p> Signup and view all the answers

<p>They add pentavalent elements that contribute an extra electron. (B)</p> Signup and view all the answers

<p>The product of majority and minority carrier concentrations is equal to the square of intrinsic concentration. (D)</p> Signup and view all the answers

<p>Carrier mobility typically increases, improving conductivity. (C)</p> Signup and view all the answers

<p>Between the conduction band and the valence band. (C)</p> Signup and view all the answers

<p>$\sigma = (N_e u_e + N_h u_h)e$ (A)</p> Signup and view all the answers

<p>It creates a significant increase in majority charge carriers. (C)</p> Signup and view all the answers

<p>The concentration of donor atoms is nearly equal to that of free electrons. (A)</p> Signup and view all the answers

<p>It is located just above the valence band. (C)</p> Signup and view all the answers

<p>Nh × Ne = Ni^2 (C)</p> Signup and view all the answers

<p>They provide additional vacancies that act as charge carriers. (B)</p> Signup and view all the answers

<p>Within the forbidden gap near the conduction band. (C)</p> Signup and view all the answers

<p>A small energy gap between valence and conduction bands (B)</p> Signup and view all the answers

<p>Sufficient external energy (D)</p> Signup and view all the answers

<p>Their conduction relies solely on temperature increase. (A)</p> Signup and view all the answers

<p>Both electrons and holes contribute to conduction (C)</p> Signup and view all the answers

<p>Non-overlapping valence and conduction bands (D)</p> Signup and view all the answers

<p>Holes move from P to N and electrons from N to P. (D)</p> Signup and view all the answers

<p>It forms a barrier against further diffusion. (D)</p> Signup and view all the answers

<p>It narrows the depletion region. (B)</p> Signup and view all the answers

<p>The potential barrier created by the depletion region. (A)</p> Signup and view all the answers

<p>It exists due to charge imbalance created by diffusion. (B)</p> Signup and view all the answers

<p>It increases. (C)</p> Signup and view all the answers

<p>Minority carriers from both sides. (C)</p> Signup and view all the answers

<p>Holes from the P-type material and electrons from the N-type material move towards the junction. (B)</p> Signup and view all the answers

<p>Enen = Eex + Ein (A)</p> Signup and view all the answers

<p>It is negligible and due to minority carriers. (C)</p> Signup and view all the answers

<p>The width of the depletion region decreases. (C)</p> Signup and view all the answers

<p>Resistance is very high, allowing negligible current. (C)</p> Signup and view all the answers

<p>$E_{nen} = E_{ex} + E_{in}$ (D)</p> Signup and view all the answers

<p>It creates a condition for either forward or reverse biasing. (D)</p> Signup and view all the answers

<p>$n_e imes p_h = n_i^2$ (D)</p> Signup and view all the answers

<p>An ideal diode behaves like a short circuit. (D)</p> Signup and view all the answers

<p>The hole concentration will increase. (A)</p> Signup and view all the answers

<p>It will approach zero. (C)</p> Signup and view all the answers

<p>It decreases the free electron concentration. (D)</p> Signup and view all the answers

<p>It marks the voltage at which current increases dramatically. (A)</p> Signup and view all the answers

<p>Dynamic resistance can be categorized as R1 &gt; R2 &gt; R3 based on increasing voltage. (B)</p> Signup and view all the answers

<p>Diffusion of majority charge carriers (C)</p> Signup and view all the answers

<p>It behaves in a non-linear fashion and does not adhere to Ohm's law. (C)</p> Signup and view all the answers

<p>Current increases rapidly as voltage continues to rise. (C)</p> Signup and view all the answers

Semiconductors are classified as elemental (like silicon and germanium) or compound (inorganic like GaAs, or organic like phthalocyanine).

Materials are categorized by their ability to conduct electricity: Conductors have high conductivity, semiconductors have moderate conductivity, and insulators have very low conductivity.

Semiconductors have a resistivity that is in the range between that of conductors and insulators.

Substances with many free electrons that conduct electricity easily.

Materials offering very high resistance to electricity flow.

Material with overlapping valence and conduction bands, allowing free movement of electrons.

Material with a small energy gap between valence and conduction bands, letting some electrons move with activation energy.

The energy difference between the valence and conduction bands in a semiconductor.

Energy band holding electrons responsible for bonding.

Energy band containing electrons available for electric conduction.

A semiconductor doped with donor impurities, creating excess free electrons in the conduction band, leading to increased conductivity.

A semiconductor doped with acceptor impurities, creating holes in the valence band, improving conductivity by allowing electrons to move through these holes.

Impurities in semiconductors like phosphorus or arsenic, with one extra valence electron that can easily jump to the conduction band, increasing conductivity.

Impurities like boron or aluminum that have one fewer valence electron than the semiconductor material creating 'holes' in the valence band to accept electrons, increasing conductivity.

The minimum energy required to excite an electron from the valence band to the conduction band, where it can freely contribute to conduction. This energy difference is denoted as $E_g$.

The energy gap between the valence band and the conduction band in a semiconductor material. In insulators, $E_g$ is greater than 5 eV, making it difficult for electrons to move to the conduction band.

A semiconductor material that is inherently pure, meaning it has a very small number of impurities. In this case, the number of free electrons ($n_e$) and holes ($n_h$) are equal, and their concentration is called the intrinsic carrier concentration ($n_i$).

As temperature increases, the concentration of intrinsic carriers ($n_i$) in an intrinsic semiconductor increases. This is because increased thermal energy excites more electrons from the valence band to the conduction band.

The conductivity of an intrinsic semiconductor is directly proportional to the square of the intrinsic carrier concentration ($n_i$). Thus, an increase in temperature, which increases $n_i$, leads to an increase in conductivity.

The conductivity of a semiconductor is determined by the sum of the contributions from both electrons and holes, weighted by their respective carrier concentrations (N_e and N_h) and mobilities (µ_e and µ_h).

Doping in semiconductors involves intentionally adding impurities (dopant atoms) to a pure semiconductor material to alter its electrical properties. These impurities create either extra electrons (N-type) or 'holes' (P-type) for enhanced conductivity.

In an N-type semiconductor, electrons are the majority carriers as they're present in higher concentrations. Holes become the minority carriers. Conversely, in a P-type semiconductor, holes are the majority carriers, and electrons are the minority carriers.

A connection point between a P-type semiconductor material (excess holes) and an N-type semiconductor material (excess electrons).

A region near the P-N junction where charge carriers (electrons and holes) are depleted, forming a barrier that prevents current flow.

An external voltage is applied in a direction that opposes the potential barrier, allowing more electrons to flow across the junction and increasing current.

The energy difference between the Fermi levels of the P-type and N-type semiconductors. It is the internal electric field generated in the depletion region, preventing current flow.

An external voltage is applied in a direction that strengthens the potential barrier, stopping current flow.

When a P-type semiconductor and an N-type semiconductor are joined, a depletion region forms at the junction due to diffusion of holes and electrons. This region has an internal electric field.

The potential barrier (V0) is the energy required for an electron to move from the N-type semiconductor to the P-type semiconductor. It's directly proportional to the width of the depletion region (d) and inversely proportional to the electric field (Ein).

In an unbiased P-N junction, no external voltage is applied. The electric field across the depletion region prevents further diffusion of charge carriers, resulting in a small current flow.

Connecting the positive terminal of a cell to the P-type material and the negative terminal to the N-type material reduces the electric field and narrows the depletion region, allowing current to flow easily.

In reverse bias, the majority carriers (electrons in N-type and holes in P-type) are repelled away from the junction.

In reverse bias, the minority carriers (holes in N-type and electrons in P-type) are attracted towards the junction, leading to a small reverse current.

Reverse biased PN junctions exhibit a very high resistance and a negligible current flow, mainly due to the drifting of minority carriers.

Reverse bias increases the potential barrier and reduces current, while forward bias reduces the barrier and increases current.

A theoretical diode with zero knee voltage, allowing current to flow freely in the forward direction and completely blocking it in reverse. It behaves like a short circuit in forward bias and an open circuit in reverse bias.

The minimum voltage required to overcome the potential barrier in a diode and allow significant current flow in forward bias.

A real-world diode with a non-zero knee voltage, limiting current flow in forward bias and allowing some leakage current in reverse bias.

The voltage value at which the current in a forward-biased P-N junction starts to rapidly increase, indicating a transition to a high-conduction state.

A characteristic of the forward-biased P-N junction diode where the current doesn't increase proportionally with the applied voltage, as in Ohm's law, but rather follows a non-linear curve.

The instantaneous change in the voltage (dV) over the corresponding change in current (dI) at a particular point on the I-V curve of a forward-biased P-N junction. It varies with the operating voltage.

The movement of majority charge carriers (either electrons in N-type or holes in P-type semiconductors) across the P-N junction in forward bias, leading to the generation of current in the circuit.