Gallium arsenide

Gallium arsenide
Gallium arsenide
General
Chem. formula	Gaas
Physical properties
condition	solid , dark gray cubic crystals
Molar mass	144.64 g / mol
Thermal properties
T. melt.	1240 ° C
Structure
Crystal structure	zinc blende; a = 0.56533 nm
Classification
Reg. CAS number
PubChem
Reg. EINECS number
Smiles
Inchi
RTECS
UN number
ChemSpider
Security
Toxicity	Not investigated, hydrolysis products are toxic

Gallium arsenide (GaAs) is a chemical compound of gallium and arsenic . An important semiconductor , the third most widely used in industry after silicon and germanium . Used to create microwave circuits and transistors , LEDs , laser diodes , Gunn diodes , tunnel diodes , photodetectors and nuclear radiation detectors.

Content

1 Properties
2 Security
3 Zone structure parameters
4 notes
5 References

Properties

The band gap at 300 K is 1.424 eV
The effective mass of electrons is 0.067 m _e
Effective mass of light holes - 0.082 m _e
The effective mass of heavy holes is 0.45 m _e
Electron mobility at 300 K - 8500 cm² / (V · s)
Hole mobility at 300 K - 400 cm² / (V · s)

Some electronic properties of GaAs are superior to those of silicon . Gallium arsenide has a higher electron mobility, which allows devices to operate at frequencies up to 250 GHz.

GaAs-based semiconductor devices generate less noise than silicon devices at the same frequency. Due to the higher electric field strength of breakdown in GaAs compared to Si, gallium arsenide devices can operate at a higher power. These properties make GaAs widely used in semiconductor lasers, some radar systems. Semiconductor devices based on gallium arsenide have a higher radiation resistance than silicon, which determines their use in radiation conditions (for example, in solar panels operating in space).

GaAs is a direct - gap semiconductor , which is also its advantage. GaAs can be used in optoelectronic devices: LEDs , semiconductor lasers .

Complex layered structures of gallium arsenide in combination with aluminum arsenide (AlAs) or triple Al _x Ga _1-x As solutions ( heterostructures ) can be grown using molecular beam epitaxy (MBE) or MOS hydride epitaxy. Due to the almost perfect matching of the constant lattices, the layers have low mechanical stresses and can be grown of arbitrary thickness.

By physical characteristics, GaAs is a more fragile and less heat-conducting material than silicon. Gallium arsenide substrates are much more difficult to manufacture and about five times more expensive than silicon, which limits the use of this material.

Security

The toxic properties of gallium arsenide have not been studied in detail, but the products of its hydrolysis are toxic (and carcinogenic ).

Zone structure parameters

The band structure of GaAs.

The band gap : in the G-valley E _g ^Г - 1.519 eV;
Varsney parameter : α (G) - 0.5405 meV / K; β (G) - 204 K
The band gap in the X- valley E _g ^X - 1,981 eV
Varsney parameter: α ( X ) - 0.460 meV / K; β ( X ) - 204 K
The band gap in the L- valley E _g ^L - 1.815 eV
Varsney parameter: α ( L ) - 0.605 meV / K; β ( L ) - 204 K
Spin-orbit splitting Δ _so - 0.341
The effective mass of the electron in the G-valley m _e ^* (G) - 0,067
The longitudinal effective mass of the electron in the L- valley m _l ^* ( L ) - 1.9
The transverse effective mass of the electron in the L- valley m _t ^* ( L ) - 0,0754
The longitudinal effective mass of the electron in the X- valley m _l ^* ( X ) is 1.3
The transverse effective mass of the electron in the X- valley m _t ^* ( X ) is 0.23
Luttinger parameters : $\gamma$ ${\ displaystyle \ gamma}$ 1-6.98; $\gamma$ ${\ displaystyle \ gamma}$ ₂ - 2.06; $\gamma$ ${\ displaystyle \ gamma}$ ₃ - 2.93
Elastic constants : c ₁₁ - 1221 GPa; c ₁₂ - 566 GPa; c ₄₄ - 600 GPa

Notes

Links

Physical properties of gallium arsenide