Aluminium arsenide () is a
semiconductor material
A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. ...
with almost the same
lattice constant
A lattice constant or lattice parameter is one of the physical dimensions and angles that determine the geometry of the unit cells in a crystal lattice, and is proportional to the distance between atoms in the crystal. A simple cubic crystal has o ...
as
gallium arsenide
Gallium arsenide (GaAs) is a III-V direct band gap semiconductor with a Zincblende (crystal structure), zinc blende crystal structure.
Gallium arsenide is used in the manufacture of devices such as microwave frequency integrated circuits, monoli ...
and
aluminium gallium arsenide
Aluminium gallium arsenide (also gallium aluminium arsenide) ( Alx Ga1−x As) is a semiconductor material with very nearly the same lattice constant as GaAs, but a larger bandgap. The ''x'' in the formula above is a number between 0 and 1 - this ...
and wider
band gap
In solid-state physics, a band gap, also called an energy gap, is an energy range in a solid where no electronic states can exist. In graphs of the electronic band structure of solids, the band gap generally refers to the energy difference (in ...
than gallium arsenide. (AlAs) can form a superlattice with
gallium arsenide
Gallium arsenide (GaAs) is a III-V direct band gap semiconductor with a Zincblende (crystal structure), zinc blende crystal structure.
Gallium arsenide is used in the manufacture of devices such as microwave frequency integrated circuits, monoli ...
(
GaAs) which results in its semiconductor properties. Because GaAs and AlAs have almost the same lattice constant, the layers have very little induced strain, which allows them to be grown almost arbitrarily thick. This allows for extremely high performance high electron mobility, HEMT transistors, and other
quantum well
A quantum well is a potential well with only discrete energy values.
The classic model used to demonstrate a quantum well is to confine particles, which were initially free to move in three dimensions, to two dimensions, by forcing them to occupy ...
devices.
Properties
It has the following properties:
*
Thermal expansion coefficient
Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature, usually not including phase transitions.
Temperature is a monotonic function of the average molecular kinetic ...
5 µm/(°C*m)
*
Debye temperature
In thermodynamics and solid-state physics, the Debye model is a method developed by Peter Debye in 1912 for estimating the phonon contribution to the specific heat (Heat capacity) in a solid. It treats the vibrations of the atomic lattice (hea ...
417 K
*
Microhardness
Indentation hardness tests are used in mechanical engineering to determine the hardness of a material to deformation. Several such tests exist, wherein the examined material is indented until an impression is formed; these tests can be performed on ...
5.0 GPa (50 g load)
*Number of atoms in 1 cm
3: (4.42-0.17x)·10
22[Dierks, S]
"Aluminum Arsenide - Material Safety Data"
. The Fitzgerald Group, MIT, 1994.
*
Bulk modulus
The bulk modulus (K or B) of a substance is a measure of how resistant to compression the substance is. It is defined as the ratio of the infinitesimal pressure increase to the resulting ''relative'' decrease of the volume.
Other moduli describe ...
(7.55+0.26x)·10
11 dyn cm
−2
*Hardness on the
Mohs scale
The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material.
The scale was introduced in 1812 by th ...
: ~ 5
*Insolubility in H
2O
Uses
Aluminium arsenide is a III-V compound
semiconductor material
A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. ...
and is an advantageous material for the manufacture of
optoelectronic
Optoelectronics (or optronics) is the study and application of electronic devices and systems that find, detect and control light, usually considered a sub-field of photonics. In this context, ''light'' often includes invisible forms of radiatio ...
devices, such as
light emitting diodes
A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (cor ...
.
Aluminium arsenide can be prepared using well-known methods, such as
liquid and vapor-phase epitaxy techniques or melt-growth techniques. However, aluminium arsenide crystals prepared by these methods are generally unstable and generate
arsine
Arsine (IUPAC name: arsane) is an inorganic compound with the formula As H3. This flammable, pyrophoric, and highly toxic pnictogen hydride gas is one of the simplest compounds of arsenic. Despite its lethality, it finds some applications in th ...
(
As H3) when exposed to moist air.
Synthesis
Little work has been reported on the preparation of aluminium arsenide, mainly because of the practical difficulties involved. Preparation from the melt is difficult because of the high
melting point
The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends ...
of the compound (about 1,700 °C) and of the extreme reactivity of aluminium at this temperature. A few workers have prepared small crystals from the melt, and
polycrystalline ingots have also been produced. The best of this material has an impurity carrier density of the order of 10
19/cm
3 and is p-type.
Reactivity
Aluminium arsenide is a stable compound; however, acid, acid fumes and moisture should be avoided. Hazardous polymerization will not occur. Decomposition of aluminium arsenide produces hazardous
arsine
Arsine (IUPAC name: arsane) is an inorganic compound with the formula As H3. This flammable, pyrophoric, and highly toxic pnictogen hydride gas is one of the simplest compounds of arsenic. Despite its lethality, it finds some applications in th ...
gas and
arsenic fumes.
Toxicity
The chemical, physical and toxicological properties of aluminium arsenide have not been thoroughly investigated and recorded.
Aluminium compounds have many commercial uses and are commonly found in industry. Many of these materials are active chemically and thus exhibit dangerous toxic and reactive properties.
Safety
Effects of exposure
Aluminium compounds have many commercial uses and are commonly found in industry. Many of these materials are active chemically and thus exhibit dangerous toxic and reactive properties. The chemical, physical and
toxicological properties of aluminium arsenide have not been thoroughly investigated and recorded; however, there are some known
chronic and
acute
Acute may refer to:
Science and technology
* Acute angle
** Acute triangle
** Acute, a leaf shape in the glossary of leaf morphology
* Acute (medicine), a disease that it is of short duration and of recent onset.
** Acute toxicity, the adverse eff ...
symptoms based on chemical delivery.
Inhalation of aluminium arsenide may cause acute irritation to the respiratory system. It may also cause chronic arsenic poisoning, ulceration of the nasal septum, liver damage and cancer/diseases of the blood, kidneys and nervous system. Aluminium arsenide is poisonous if ingested and may cause gastrointestinal and skin effects and acute
arsenic poisoning
Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but o ...
. Chronic implications from ingestion include arsenic poisoning, gastrointestinal disturbances, liver damage, and cancer/disease of the blood, kidneys and nervous system. If applied to the skin, aluminium arsenide may cause acute irritation, but there are no chronic health effects recorded.
[Sax. ''Dangerous Properties of Industrial Materials''. Eighth edition. 2005.]
Special precautions
Precautions to be taken in handling and storage: Store in a cool, dry place in tightly sealed containers. Ensure there is good ventilation. Open and handle container with care. Do not store together with acids. Keep container tightly sealed.
References
External links
{{Arsenides
Arsenides
Aluminium compounds
III-V semiconductors
III-V compounds
Zincblende crystal structure