Semiconductor Diodes and p-n Junctions

<p>Conventional current flow under forward bias (C)</p> Signup and view all the answers

<p>It decreases, allowing current to flow (C)</p> Signup and view all the answers

<p>To reduce the intrinsic concentration of minority carriers. (C)</p> Signup and view all the answers

<p>Slightly below the bottom EC of the conduction band. (D)</p> Signup and view all the answers

<p>Majority carriers are destroyed. (D)</p> Signup and view all the answers

<p>Ionization of acceptor atoms. (B)</p> Signup and view all the answers

<p>It ionizes the acceptor negatively and leaves a hole. (B)</p> Signup and view all the answers

<p>They increase the chances of destruction of minority carriers. (D)</p> Signup and view all the answers

<p>From donors ionizing at room temperature. (A)</p> Signup and view all the answers

<p>They are predominantly due to ionization of acceptor atoms. (A)</p> Signup and view all the answers

<p>They move into the conduction band, creating vacant levels. (D)</p> Signup and view all the answers

<p>It is completely empty of electrons. (B)</p> Signup and view all the answers

<p>8N (C)</p> Signup and view all the answers

<p>Energy band gap (D)</p> Signup and view all the answers

<p>Electrons that are involved in bonding. (B)</p> Signup and view all the answers

<p>Both Si and Ge have 4 electrons in their outermost orbit. (D)</p> Signup and view all the answers

<p>It is completely filled with electrons. (B)</p> Signup and view all the answers

<p>It influences the grouping of energy levels into bands. (D)</p> Signup and view all the answers

<p>The total current is the sum of the currents from both electrons and holes. (A)</p> Signup and view all the answers

<p>At absolute zero, 0 K. (A)</p> Signup and view all the answers

<p>Thermal energy at temperatures greater than 0 K. (B)</p> Signup and view all the answers

<p>The rates of generation and recombination of charge carriers are equal. (D)</p> Signup and view all the answers

<p>Recombination occurs when an electron collides with a hole. (A)</p> Signup and view all the answers

<p>They partially occupy the conduction band. (B)</p> Signup and view all the answers

<p>Carbon has no free electrons while silicon and germanium have more available electrons. (A)</p> Signup and view all the answers

<p>It shows thermally generated electron-hole pairs. (A)</p> Signup and view all the answers

<p>Eg &gt; 3 eV (A)</p> Signup and view all the answers

<p>The junction barrier decreases. (B)</p> Signup and view all the answers

<p>They can be excited from the valence band. (C)</p> Signup and view all the answers

<p>Immobilized ion-cores (D)</p> Signup and view all the answers

<p>Eg &lt; 0.2 eV (C)</p> Signup and view all the answers

<p>Rectifying AC voltage (D)</p> Signup and view all the answers

<p>By altering the relative stoichiometric ratio (C)</p> Signup and view all the answers

<p>Increase in barrier height (D)</p> Signup and view all the answers

<p>10–2 to 10–8 W m (C)</p> Signup and view all the answers

<p>Has an equal number of electrons and holes (B)</p> Signup and view all the answers

<p>ne &gt;&gt; nh (B)</p> Signup and view all the answers

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

<p>They are vacancies for electrons with an effective positive charge (C)</p> Signup and view all the answers

<p>Electrons in this band are free to move and contribute to conductivity (D)</p> Signup and view all the answers

<p>nh &gt;&gt; ne (D)</p> Signup and view all the answers

<p>nenh = ni2 (B)</p> Signup and view all the answers

The energy difference between the valence band (where electrons are normally located) and the conduction band (where electrons can freely move to conduct electricity).

The band of energy levels containing electrons that are tightly bound to atoms and are not free to move. Most electrons in a semiconductor reside here at absolute zero.

The band of energy levels above the valence band where electrons can freely move, enabling electrical conductivity.

The movement of electrons in a material, creating an electric current.

Materials that have a moderate energy band gap, allowing them to conduct electricity under certain conditions. Examples include silicon (Si) and germanium (Ge).

Materials with a very large energy band gap, making it very difficult for electrons to conduct electricity.

Materials with a very small energy band gap, allowing electrons to easily conduct electricity.

The temperature at which all molecular motion stops and all substances are theoretically in their most stable state.

The total current (I) flowing through a semiconductor is the sum of the electron current (Ie) and the hole current (Ih).

At equilibrium, the rate of generation of electron-hole pairs is equal to the rate of recombination of these pairs.

Recombination occurs when an electron collides with and recombines with a hole, effectively neutralizing both charge carriers.

Thermal energy at temperatures above absolute zero can excite electrons from the valence band to the conduction band, creating electron-hole pairs and increasing conductivity.

In an intrinsic semiconductor at absolute zero (T = 0 K), all electrons occupy the valence band and the material behaves like an insulator.

In an intrinsic semiconductor at temperatures above absolute zero (T > 0 K), electrons are thermally excited to the conduction band, creating electron-hole pairs and enabling some conductivity.

Carbon (C) is an insulator, while silicon (Si) and germanium (Ge) are intrinsic semiconductors because they have different energy band gaps.

An intrinsic semiconductor possesses properties based on the inherent nature of its material, without any external doping.

The area within a p-n junction where there are very few free charge carriers (electrons and holes). It acts as a barrier to current flow.

The potential difference that exists across the depletion region of a p-n junction when it is in equilibrium (no external voltage applied).

A semiconductor diode is made by joining a p-type and an n-type semiconductor material. The junction between these materials is called a p-n junction.

The process of applying an external voltage to a semiconductor diode to reduce the barrier potential and make it easier for current to flow.

The process of applying an external voltage to a semiconductor diode in a way that increases the barrier potential and makes it harder for current to flow.

The process where thermally generated minority carriers in a semiconductor combine with majority carriers, leading to their destruction.

The energy level within a semiconductor where donor impurities (atoms with extra valence electrons) are located. It's slightly below the conduction band, making it easier for electrons to jump into the conduction band.

The energy level within a semiconductor where acceptor impurities (atoms with missing valence electrons) are located. It's slightly above the valence band, making it easier for electrons to jump from the valence band to this level.

The process of adding impurities to a pure semiconductor to increase its conductivity. This is done by adding atoms with either extra or missing valence electrons.

A semiconductor where the majority of charge carriers are electrons. This is achieved by adding donor impurities, which provide extra electrons to the conduction band.

A semiconductor where the majority of charge carriers are holes. This is achieved by adding acceptor impurities, which create holes in the valence band.

The process where electrons move from the valence band to a higher energy level, creating a 'vacancy' or 'hole' in the valence band. This hole can then move as a positive charge carrier.

The ability of a material to conduct electricity. It is determined by the ease with which electrons can move through the material.

The energy difference between the valence band and the conduction band. Electrons must gain enough energy to jump this gap to become free and conduct electricity.

The difference in energy between the valence band, where electrons are normally found, and the conduction band, where electrons can move freely to conduct electricity.

A semiconductor behaves as an insulator at very low temperatures due to its large energy gap, preventing electron excitation from the valence band to the conduction band.

As temperature rises, electrons in a semiconductor gain thermal energy, overcoming the energy gap and moving to the conduction band, increasing its conductivity because more electrons can flow.

A p-n junction is formed when a p-type semiconductor is joined with an n-type semiconductor. It forms a depletion layer (empty of free charge carriers) due to the diffusion of electrons and holes across the junction.

An external voltage applied to a p-n junction can alter the width of the depletion layer, affecting its conductivity. In forward bias, the depletion layer narrows, allowing more current to flow, while in reverse bias, it widens, restricting current.

A diode is a device that allows current to flow in only one direction, allowing us to convert alternating current (AC) to direct current (DC) by blocking current in the reverse direction.

An AC voltage can be converted to a DC voltage using a diode and a filter. The diode restricts the AC current to one direction, and the filter smooths out the remaining ripple.

In compound semiconductors, the relative proportions of different elements can change the type of semiconductor, instead of doping. Changing the composition alters the energy levels and affects conductivity.