Heterostructures

Heterostructures.

 

 

Semiconductor heterostructures are used in the creation of modern transistors, lasers, LEDs, solar panels, thyristors, etc.

 


Heterostructures:

Heterostructure – an artificially created layered solid structure, made of two or more semiconductors made of a different chemical composition materialsin which the important role belongs to the transition layer, i.e. the interface of two semiconductors is called a heterojunction, and wherein a width of the forbidden zone.

The heterostructure is an artificially created layered solid-state structurecontaining multiple heterojunctions.

Bandgap is the minimum energy required to move an electron from the valence band to the conduction band. The values of the band gap in semiconductors range from 0.1 to 4 eV.

On width of forbidden zone of all solid materials differ in their electric properties and are divided into conductors, semiconductors and insulators. First, no forbidden zone, and the latter she is more than 4 eV.

In semiconductors the electrons from the valence band, breaking the forbidden zone (at nonzero temperature) fall in the zone of conduction and start to participate in conduction, that is, to move under the influence of an electric field.

The band gap causes the transparency of the semiconductor material for photons with energy smaller that width. On the contrary, photons with energy greater than the band gap, are absorbed by the semiconductor. The absorption of photons by the semiconductor is accompanied by the transfer of photon energy to electrons or atoms.

The reverse process – recombination – the disappearance of a pair of free carriers of opposite charge (electrons and holes) in semiconductors, followed by the release of energy that is carried away by photons. In some heterostructures the energy of the external source can almost completely be converted into light energy.

Under the heterojunction refers to a junction of two different chemical composition of the semiconductor in which the crystal lattice of one material without violating the periodicity goes into the lattice of another material, thereby forming a single crystalline lattice of these materials.

To create high-quality heterojunctions, i.e. in order for the heterostructure does not have any internal defects, it is necessary that semiconductor materials have had the same crystal structure and close lattice periods.

By creating a heterostructure can effectively control the movement of charge carriers, their recombination and light streams inside them (inside semiconductor heterostructures).

The properties of the obtained fully depend on the type and order of its constituent two-dimensional layers.

To obtain the heterostructures using the following methods:

– molecular beam epitaxy,

– deposition of ORGANOMETALLIC compounds from the gas phase,

– chemical Assembly.

Semiconductor heterostructures used to create transistors, lasers, LEDs, solar panels, thyristors, etc.

 

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