Gasphasenepitaxie

Gasphasenepitaxie, known in English as gas‑phase epitaxy, is a surface science technique for producing crystalline thin films on substrates under controlled vapor conditions. The method relies on the adsorption of gaseous precursors onto the heated substrate surface, where they decompose, rearrange, and form a single‑crystal lattice that matches the underlying substrate.

The earliest gas‑phase epitaxy work dates back to the 1950s, when research groups used phosphine and arsine gases to grow gallium arsenide layers in vacuum furnaces. Since then, the field has expanded to include several techniques distinguished by their transport and decomposition mechanisms. Metal‑organic chemical vapor deposition (MOCVD) employs metal‑organic and hydride gases, and is widely used in the production of light‑emitting diodes, laser diodes and high‑electron‑mobility transistors. Metal‑organic vapor phase epitaxy (MOVPE) is a variant where organometallic precursors are introduced with hydrogen or other carrier gases. Atomic layer deposition (ALD) is a precursor‑based, self‑limiting gas‑phase process that allows sub‑nanometer control of film thickness and is important for dielectric layers and tunnel junctions.

Gas‑phase epitaxy offers several advantages over solid‑phase methods. Because the substrate is never in direct contact with a molten material, the process can be gentler, reducing defect formation. It also allows precise compositional grading, creating heterostructures with abrupt interfaces, which is essential for modern semiconductor devices. However, the requirement for high‑purity gases, high temperatures, and the handling of toxic or pyrophoric precursors impose stringent safety and cost considerations.

Today, gas‑phase epitaxy remains a cornerstone of advanced semiconductor manufacturing, enabling the growth of III–V, II–VI, and more recently perovskite and other novel materials for photovoltaics, electronics, and photonics. Its continuous evolution, driven by new precursor chemistries and in‑situ monitoring technologies, keeps it at the forefront of thin‑film research.