Indium nitride

The indium nitride (InN) is semiconductor of family III-V, all the nitride of aluminum (AlN) and the nitride of gallium (GaN). Semiconductors III-V know an growing interest in the scientific world for several reasons

they are robust,
have a high thermal conductivity
their point melting is high
they have a forbidden band (usually called gap) direct

These materials are mainly used in the photovoltaic cells and the optoelectronic devices such as electroluminescent diodes (French LED or English LED for Light Emitting Diode). AlN, GaN and InN respectively have energies of forbidden bands of 6.2eV, 3.4eV and ~0.7eV.

However, as we will see it, the indium nitride remains marginalized.

A strange material III-V

A marginalized material

Whereas AlN and GaN are now well-known materials, it is not the case of InN whereas it belongs to same family III-V. One estimates knowledge about InN equivalent to those of GaN ten years ago! It should be known that currently InN is created by epitaxy by molecular jets. However many difficulties of growth are encountered:

lack of substrates having a weak dissension of mesh
a low temperature of dissociation of InN
a nitrogen vapor high pressure in the presence of InN

An abnormally conducting material III-N

The studies on InN revealed an abnormally raised conductivity. Two assumptions were put forth to explain this conductivity: an oxidation or a phenomenon of curves of bands. Each assumption having for consequence an accumulation of electrons on the surface. For the moment, the track of the curve of band is most probable by far. In 2001, W. Waluckiewicz introduced a model calling upon the energy of stabilization of Fermi which connects the defects of surface to the phenomenon of anchoring ( pinning ) of the energy level of Fermi on the surface of the semiconductors.

Essential properties of InN

Crystallographic properties

Polarities of the faces

Origin of polarization

N-face and In-face

Optical properties

Structure of bands

Variation of the energy of forbidden band with the temperature

Nanocolonnes d' InN

Technological applications

By combining Ga, In and Indium, one can obtain a forbidden band varying from 0.7 with 3.4eV. This range of energy covers the visible spectrum. Moreover energy of forbidden band is direct. This material is thus ideal for the development of photovoltaic cells. For these same reasons, one uses also indium in the ternary compound InGaN for the realization of electroluminescent diodes.

Notes and references of the article

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