Epitaxy - close and far away from thermodynamic equilibrium

The enormously wide field of epitaxy cannot be covered in one paper since there are so many different methods partly specially designed or modified for the application for distinct materials. Therefore, this contribution is restricted to two epitaxial growth techniques, namely the Hot-Wall-Epitaxy (HWE) and the Atomic-Layer-Epitaxy (ALE), together with their modifications the Hot-Wall-Beam-Epitaxy and the Self-Limiting-Monolayer-Epitaxy. The main difference between HWE and ALE can be described in terms of thermodynamics. The HWE works very close to thermodynamic equilibrium, whereas the ALE is far away from thermodynamic equilibrium conditions. The main advantages and disadvantages will be elaborated, together with some significant applications for the growth of single layers, multilayers, superlattices and quantum well structures of II-VI compounds or organic semiconductors.