Epitaksjon

Epitaksjon is a process in materials science where a new crystalline layer is grown on top of a crystalline substrate. The deposited layer, known as the epitaxial layer, adopts the same crystallographic orientation as the substrate. This means that the atoms in the new layer align themselves with the atomic structure of the underlying material. The term "epitaxy" itself comes from Greek words meaning "arrangement upon."

There are two main types of epitaxy: homoepitaxy and heteroepitaxy. Homoepitaxy involves growing a layer of the same material as the substrate. For example, growing silicon on a silicon substrate. Heteroepitaxy, on the other hand, involves growing a layer of a different crystalline material on a substrate. An example would be growing gallium arsenide on a silicon substrate.

Epitaxy is a crucial technique in the fabrication of semiconductor devices. It allows for the precise control of the composition, thickness, and crystal quality of thin films, which are essential for creating transistors, diodes, and integrated circuits. The process typically involves vapor-phase deposition methods, such as Chemical Vapor Deposition (CVD) or Molecular Beam Epitaxy (MBE). These methods allow for the controlled introduction of precursor materials that react and deposit onto the heated substrate, forming the epitaxial layer. The purity and structural perfection of the substrate and the deposition process are critical for achieving high-quality epitaxial layers, which directly impacts the performance and reliability of electronic and optoelectronic devices.