Epitaxy is the family of processes that grow a single-crystal film in registry with a crystalline substrate, and it remains the step that sets the performance ceiling for power transistors, photonic and quantum emitters, and most exotic thin-film phases.
Summary
Epitaxy means growing a crystalline layer whose atomic lattice is aligned to that of the substrate underneath it. Rather than depositing an amorphous or polycrystalline film, the arriving atoms find lattice sites dictated by the surface below, so the film inherits its orientation and, if the lattice constants differ, a defined state of strain. This is how essentially every compound-semiconductor device stack is made: heterostructures, quantum wells, doped channels and buffer layers are all built by stacking epitaxial layers of controlled composition and thickness.
Several distinct techniques share the name. Molecular beam epitaxy (MBE) evaporates elemental sources in ultra-high vacuum onto a heated substrate, giving monolayer-level control and in-situ diagnostics via reflection high-energy electron diffraction (RHEED); the sources here use it for everything from single- to five-layer MoS2 on graphene/Ir(111) to PtTe2 films grown with single-monolayer precision from 1 to 20 ML. Metal-organic vapour phase epitaxy (MOVPE) uses gaseous precursors at high temperature and is the workhorse for nitrides. Halide vapour phase epitaxy (HVPE) trades some control for rate, reaching up to 30 µm/hr for β-Ga2O3 on sapphire. Liquid-phase epitaxy is used in ambient conditions for oriented metal-organic framework films by spin-assisted layer-by-layer deposition, and thermal laser epitaxy uses a focused high-power laser to evaporate refractory targets.
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Assessment drafted 2026-08-31 from up to 18 KB sources using the technology-scorecard framework; scores are a draft read pending review.