Domain epitaxy: A unified paradigm for thin film growth

Abstract

We present a unified model for thin film epitaxy where single crystal films with small and large lattice misfits are grown by domain matching epitaxy (DME). The DME involves matching of lattice planes between the film and the substrate having similar crystal symmetry. In this framework, the conventional lattice matching epitaxy becomes a special case where a matching of lattice constants or the same planes is involved with a small misfit of less than 7%–8%. In large lattice mismatch systems, we show that epitaxial growth of thin films is possible by matching of domains where integral multiples of major lattice planes match across the interface. We illustrate this concept with atomic-level details in the TiN/Si(100) with 3/4 matching, the AlN/Si(100)with 4/5 matching, and the ZnO/α−Al2O3(0001) with 6/7 matching of major planes across the film/substrate interface. By varying the domain size, which is equal to intregral multiple of lattice planes, in a periodic fashion, it is possible to accommodate additional misfit beyond perfect domain matching. Thus, we can potentially design epitaxial growth of films with any lattice misfit on a given substrate with atomically clean surfaces. In situ x-ray diffraction studies on initial stages of growth of ZnO films on sapphire correctly identify a compressive stress and a rapid relaxation within 1 to 2 monolayers, consistent with the DME framework and the fact that the critical thickness is less than 1 monolayer. DME examples ranging from the Ge–Si/Si(100) system with 49/50 matching (2% strain) to metal/Si systems with 1/2 matching (50% strain) are tabulated, strategies for growing strain-free films by engineering the misfit to be confined near the interface are presented, and the potential for epitaxial growth of films with any lattice misfit on a given substrate with atomically clean surfaces is discussed.

RETRACTED ARTICLE: Fundamental Discovery of New Phases and Direct Conversion of Carbon into Diamond and hBN into cBN and Properties

“…According to the domain epitaxy paradigm, 15 {110} half-planes match with 16 (À2110) planes of sapphire to accommodate the planar lattice misfit. [34] These results on epitaxial growth are fully consistent with cross-section TEM results, shown in Figure 7(a) for diamond and Figure 15(a) for cBN. Since diamond and cBN are grown from super undercooled liquid, they can be doped with both n-and p-type dopants.…”

“…By providing a planar matching (0001) sapphire epitaxial template for diamond as well as cBN growth from super undercooled liquid, we have obtained large-area single-crystal thin films through domain matching epitaxy paradigm, where large misfit is accommodated by integral multiple matching of lattice planes across the film/substrate interface. [34] Table III provides a summary of domain matching epitaxy parameters to accommodate large lattice misfit between diamond/sapphire and cBN/sapphire interfaces. [34] Figure 16(a) shows a large-area single-crystal h111i diamond thin film which has grown epitaxially on (0001) sapphire substrate with a following epitaxial relationships: h111i dia // h0001isapphire out of the plane and in-plane h110i diamond // hÀ2110i sapphire.…”

“…[34] Table III provides a summary of domain matching epitaxy parameters to accommodate large lattice misfit between diamond/sapphire and cBN/sapphire interfaces. [34] Figure 16(a) shows a large-area single-crystal h111i diamond thin film which has grown epitaxially on (0001) sapphire substrate with a following epitaxial relationships: h111i dia // h0001isapphire out of the plane and in-plane h110i diamond // hÀ2110i sapphire. According to the domain epitaxy paradigm, 19 {110} half-planes match with 20 (À2110) planes of sapphire to accommodate the planar lattice misfit.…”

Antiferromagnetic domain size and exchange bias

“…Previously, the dislocation density at the Co/ FeF 2 interface ͑dislocations help relieve misfit strain between the AF film and substrate͒ 51 was measured with transmission electron microscopy and found to be about half of what would be expected to fully relieve the mismatch between the lattice parameters of FeF 2 and MgF 2 . 32,52,53 Here, we have shown that microstrain is indeed present in the FeF 2 film.…”

Epitaxial orientation of Mg2Si(110) thin film on Si(111) substrate

“…To understand how this huge lattice mismatch was accommodated between Mg 2 Si and Si, its interfacial structure was investigated. To do this, Fourier-filtered TEM image of the interfacial region 14 was acquired from Fig. 2͑b͒ and the result is shown in Fig.…”