The method provides for the growth of an epitaxial layer (200) made of a first semiconductor material on a substrate (100) made of a second semiconductor material; the materials are different and have different CTEs; the method comprises the steps of: A) patterning the substrate (100) by an etching process so to form an array of pillars (110), the pillars (110) being laterally spaced from each other and having a top section (112) larger than a bottom section (114) and/or intermediate sections (116), B) depositing the second semiconductor material on top of the pillars (110) at a growth temperature so to form an epitaxial layer (200) generated by vertical and lateral growth, and C) inducing breaking of the pillars (110) by cooling the substrate (100) and the epitaxial layer (200) below the growth temperature.

A method of manufacturing a field-effect transistor device includes forming a bottom electrode, forming a ferroelectric layer over the bottom electrode, forming a seed layer over the ferroelectric layer, forming a channel layer on the seed layer, and forming source/drain electrodes at sidewalls of the channel layer. The seed layer is formed by using a physical vapor deposition (PVD) process, and the seed layer has a quasi-crystalline structure. The channel layer has a spinel structure.

A seed substrate for epitaxial growth has a support substrate, a planarizing layer of 0.5 to 3 m provided on the top surface of the support substrate, and a seed crystal layer provided on the top surface of the planarizing layer. The support substrate includes a core of group III nitride polycrystalline ceramics and a 0.05 to 1.5 m encapsulating layer that encapsulates the core. The seed crystal layer is provided by thin-film transfer of 0.1 to 1.5 m of the surface layer of Si<111> single crystal with oxidation-induced stacking faults (OSF) of 10 defects/cm.sup.2 or less. High-quality, inexpensive seed substrates with few crystal defects for epitaxial growth of epitaxial substrates and solid substrates of group III nitrides such as AlN, AlxGa1-xN (0<X<1) and GaN are obtained.