What is epitaxy?
It is a process of growing multiple atomic layers of semiconductor compounds on a given monocrystalline substrate such as gallium arsenide or indium phosphide. Apart from technological know-how and hands-on epitaxy experience, a thorough understanding of equipment capabilities and cleanroom environment standards is also required to maintain full process control. The right equipment is equally important: the facility should have all most recent improvements and state-of-the-art tools.
So-called epi-wafers, the product of epitaxy process, can be grown on a few types of substrates. Our Epitaxy Division focuses on gallium arsenide (GaAs) and indium phosphide (InP), which are used extensively in photonics and microelectronics applications. Those semiconductor materials are the backbone of quantum communication, 3D sensing in vehicles and consumer products, green energy such as photovoltaic cells, infrared proximity detection in defense industry, and many more.
Our company specializes in the production of top quality III-V epitaxial structures, manufactured to specification. We have extensive expertise in a wide variety of epitaxial products and offer our epi-wafers in small as well as large batches.
A substrate is a mechanical carrier and acts as a crystallography pattern for the epitaxy structure. It means that e.g. GaAs related structures would need a GaAs substrate to ensure lattice matched crystal growth.
Semiconductor substrates are manufactured by growing a semiconductor bulk crystal by Czochralsky or Bridgman technique. The surface is the most critical feature of the wafer, so it has to undergo series of processes to ensure its atomic scale roughness and lack of any impurities. To prepare epi-ready wafers the substrates are subject to mechano-chemical polishing, followed by the cleaning process.
From electrical point of view substrates can be divided into low resistive N-type and semi-insulating. N-type GaAs wafers are doped with silicon and N-type InP ones with sulphur. Semi-insulating GaAs is undoped semiconductor while semi-insulating InP have to be doped with Fe. InP substrates enable to produce lasers of higher wavelength, but, due to more complicated bulk-crystal technology, the substrates are much more expensive.
GaAs finds application in the following devices:
- QW edge emitting lasers,
- FETs, Schottky diodes,
- High-electron-mobility transistors,
- Strained QW edge emitting lasers,
- Fabry-Perrot MQW lasers ,
- Strained QW lasers,
- QD lasers,
- Passive waveguides.
InP find application in the following devices:
- Strained or matched QW edge emitting lasers,
- SOAs 1300 – 1600 nm,
- VCSEL structures,
- Passive devices,