Gallium Arsenide Unit Cell Structure
SKU: 68762W
Build an aluminium gallium arsenide (AlGaAs) unit cell with the Indigo® 68762W molecular model kit to demonstrate Td point group symmetry, zinc blende crystal structure, and bandgap engineering in III-V ternary semiconductor alloys. Ideal for solid state chemistry, semiconductor physics, materials science, and optoelectronics courses.
The Indigo® 68762W kit can build an aluminium gallium arsenide (AlxGa1-xAs) unit cell molecular model. AlGaAs has a zinc blende crystal structure and belongs to the Td point and F4?3m crystallographic space groups. It consists of two interpenetrating face-centered cubic sublattices offset by one quarter of the body diagonal. The Group V arsenic (As) atoms occupy one FCC sublattice, shown in yellow in the model, while aluminium (Al) and gallium (Ga) atoms randomly share the second FCC sublattice, shown in blue. Each atom is tetrahedrally coordinated by four atoms of the opposite type, giving a 4:4 coordination geometry consistent with the sp3 covalent bonding character of III-V semiconductors.
AlGaAs Crystal Symmetry: Zinc Blende Structure and Bandgap Engineering
The Td point group of the AlGaAs zinc blende structure lacks an inversion center which makes AlGaAs piezoelectric. All vibrational modes are both IR and Raman active. An important of AlGaAs system is its continuously tunable direct bandgap from 1.42 eV (GaAs) to approximately 1.97 eV (Al0.45Ga0.55As) enabling precise wavelength tuning from infrared visible red. The physical unit cell model makes this tunability concept tangible since students can visualize Al atoms substituted for Ga atoms leave the As sublattice and overall zinc blende structure unchanged.
AlGaAs Applications: Lasers, LEDs, Solar Cells and High-Speed Electronics
AlGaAs/GaAs double heterostructure laser diodes were the first practical room-temperature continuous-wave semiconductor lasers. These heterostructure lasers are used in CD and DVD players, laser printers, barcode scanners, and fiber optic communications. AlGaAs/GaAs high electron mobility transistors (HEMTs) achieve the highest operating frequencies of any transistor technology, making them essential components in satellite communications, radar systems, and 5G wireless infrastructure. In photovoltaics, AlGaAs/GaAs multijunction solar cells hold the world record for single-junction solar cell efficiency and are the preferred technology for space power systems on satellites and the International Space Station.
Indigo Instruments has held inventory of genuine Cochranes of Oxford (Orbit) parts for 30+ years (See Skeletal (Orbit/Minit)) that are compatible with every molecular model we have sold since day 1. This level of quality may appear expensive but no parts support from other vendors costs even more.
