Epitaxy

About: Epitaxy is a research topic. Over the lifetime, 38168 publications have been published within this topic receiving 645844 citations. The topic is also known as: Epitaxial Growth.

Epitaxial Growth of a Silicene Sheet

Abstract: Using atomic resolved scanning tunneling microscopy, we present here the experimental evidence of a silicene sheet (graphene like structure) epitaxially grown on a close-packed silver surface (Ag(111)). This has been achieved via direct condensation of a silicon atomic flux onto the single-crystal substrate in ultra-high vacuum conditions. A highly ordered silicon structure, arranged within a honeycomb lattice is synthesized and presenting two silicon sub-lattices occupying positions at different heights (0.02 nm) indicating possible sp2-sp3 hybridizations.

Thick GaN Epitaxial Growth with Low Dislocation Density by Hydride Vapor Phase Epitaxy

Abstract: Thick GaN layers were grown by hydride vapor phase epitaxy (HVPE) with the aim of using these layers as a homoepitaxial substrate to improve device quality of laser diodes or light emitting diodes. HVPE is very useful for thick layer growth since the growth rate can reach from several ten up to one hundred micron per hour. In this experiment, the growth began as selective growth through openings formed in a SiO2 mask. Facets consisting of {1101} planes were formed in the early stage and a continuous film developed from the coalescence of these facets on the SiO2 mask. As a result, GaN layers with a dislocation density as low as 6×107 cm-2 were grown on 2-inch-diameter sapphire wafers. These GaN layers were crack-free and had mirror-like surface.

van der Waals Epitaxy of MoS2 Layers Using Graphene As Growth Templates

Abstract: We present a method for synthesizing MoS2/Graphene hybrid heterostructures with a growth template of graphene-covered Cu foil. Compared to other recent reports,(1, 2) a much lower growth temperature of 400 °C is required for this procedure. The chemical vapor deposition of MoS2 on the graphene surface gives rise to single crystalline hexagonal flakes with a typical lateral size ranging from several hundred nanometers to several micrometers. The precursor (ammonium thiomolybdate) together with solvent was transported to graphene surface by a carrier gas at room temperature, which was then followed by post annealing. At an elevated temperature, the precursor self-assembles to form MoS2 flakes epitaxially on the graphene surface via thermal decomposition. With higher amount of precursor delivered onto the graphene surface, a continuous MoS2 film on graphene can be obtained. This simple chemical vapor deposition method provides a unique approach for the synthesis of graphene heterostructures and surface funct...

Epitaxial growth of single-domain graphene on hexagonal boron nitride

Abstract: The epitaxial growth of large-area single-domain graphene on hexagonal boron nitride by plasma-assisted deposition is now reported. New sets of Dirac points are produced as a result of a trigonal superlattice potential, while Dirac fermion physics near the original Dirac point remain unperturbed. This growth approach could enable band engineering in graphene through epitaxy on different substrates.

Substrates for gallium nitride epitaxy

Abstract: In this review, the structural, mechanical, thermal, and chemical properties of substrates used for gallium nitride (GaN) epitaxy are compiled, and the properties of GaN films deposited on these substrates are reviewed. Among semiconductors, GaN is unique; most of its applications uses thin GaN films deposited on foreign substrates (materials other than GaN); that is, heteroepitaxial thin films. As a consequence of heteroepitaxy, the quality of the GaN films is very dependent on the properties of the substrate—both the inherent properties such as lattice constants and thermal expansion coefficients, and process induced properties such as surface roughness, step height and terrace width, and wetting behavior. The consequences of heteroepitaxy are discussed, including the crystallographic orientation and polarity, surface morphology, and inherent and thermally induced stress in the GaN films. Defects such as threading dislocations, inversion domains, and the unintentional incorporation of impurities into the epitaxial GaN layer resulting from heteroepitaxy are presented along with their effect on device processing and performance. A summary of the structure and lattice constants for many semiconductors, metals, metal nitrides, and oxides used or considered for GaN epitaxy is presented. The properties, synthesis, advantages and disadvantages of the six most commonly employed substrates (sapphire, 6H-SiC, Si, GaAs, LiGaO 2 , and AlN) are presented. Useful substrate properties such as lattice constants, defect densities, elastic moduli, thermal expansion coefficients, thermal conductivities, etching characteristics, and reactivities under deposition conditions are presented. Efforts to reduce the defect densities and to optimize the electrical and optical properties of the GaN epitaxial film by substrate etching, nitridation, and slight misorientation from the (0 0 0 1) crystal plane are reviewed. The requirements, the obstacles, and the results to date to produce zincblende GaN on 3C-SiC/Si(0 0 1) and GaAs are discussed. Tables summarizing measures of the GaN quality such as XRD rocking curve FWHM, photoluminescence peak position and FWHM, and electron mobilities for GaN epitaxial layers produced by MOCVD, MBE, and HVPE for each substrate are given. The initial results using GaN substrates, prepared as bulk crystals and as free-standing epitaxial films, are reviewed. Finally, the promise and the directions of research on new potential substrates, such as compliant and porous substrates are described.