May 2 2013
Aluminum gallium arsenide AlxGa1-xAs) is a semiconductor material having almost the same lattice constant as gallium arsenide but a bigger bandgap. The x in the formula is a number between 0 and 1 indicating an alloy between gallium arsenide and aluminum arsenide.
The bandgap is in the range 1.42 eV (GaAs) to 2.16 eV (AlAs). The bandgap is direct when x < 0.4.
Applications
The applications of aluminum gallium arsenide are:
- It is used as a barrier material in GaAs-based heterostructure devices.
- The electrons are confined to a gallium arsenide region by the AlGaAs layer. An example of this kind of device is a quantum well-infrared photodetector (QWIP).
- It also finds application in 1064 nm (Infra-red) laser diodes.
Chemical Properties
The chemical properties of aluminum gallium arsenide are:
| Chemical Properties |
| Chemical Formula |
AlGaAs |
| Group |
III-V |
| Band Gap |
1.42 – 2.16 eV |
| Band Gap Type |
Direct when x<0.4 |
| Crystal Structure |
Zinc Blende |
| Symmetry Group |
TD2-F43m |
| Lattice Constant |
5.6533+0.0078x Å |
Electrical Properties
The electrical properties of aluminum gallium arsenide are:
| Electrical Properties |
| Intrinsic Carrier Concentration |
x=0.1 2.1•105 cm-3
x=0.3 2.1•103 cm-3
x=0.5 2.5•102 cm-3
x=0.8 4.3•101 cm-3 |
| Electron Mobility |
02 V -1 s-1
0.452 V-1 s-1 |
| Hole Mobility |
370-970x+740x2 cm2 V-1 s-1 |
| Electron Diffusion Coefficient |
02/s
0.452/s |
| Hole Diffusion Coefficient |
9.2-24x+18.5x2 cm2/s |
| Electrical Resistivity |
x=02/s
0.452/s |
Thermal, Mechanical and Optical Properties
The thermal, mechanical, and optical properties of aluminum gallium arsenide are:
| Mechanical Properties |
| Melting Point |
1414 °C |
| Density |
2.329 g cm-3 |
| Young's Modulus |
130-188 GPa |
| Shear Modulus |
51-80 GPa |
| Bulk Modulus |
(7.55+0.26x)•1011 dyn cm-2 |
| Specific Heat (@ 298 K) |
0.33+0.12x J g-1°C-3 |
| Thermal Properties |
| Thermal Conductivity |
0.55-2.12x+2.48x2 W cm-1 °C-1 |
| Thermal Diffusivity |
0.31-1.23x+1.462 cm2s-1 |
| Thermal Expansion Coefficient |
2.6x10-6 °C-1 |
| Optical Properties |
| Infrared Refractive Index (@ 300 K) |
n=3.3-0.53x+0.09x2 |
Safety Information
The toxicology of aluminum gallium arsenide has not been investigated completely. The dust may irritate the eyes, skin, and lungs.