Thermodynamics of GaO Heteroepitaxy and Material Growth Via Metal Organic Chemical Vapor Deposition.

Heteroepitaxy of gallium oxide (GaO) is gaining popularity to address the absence of p-type doping, limited thermal conductivity of GaO epilayers, and toward realizing high-quality p-n heterojunction. During the growth of β-GaO on 4H-SiC (0001) substrates using metal-organic chemical vapor deposition, we observed formation of incomplete, misoriented particles when the layer was grown at a temperature between 650 °C and 750 °C. We propose a thermodynamic model for GaO heteroepitaxy on foreign substrates which shows that the energy cost of growing β-GaO on 4H-SiC is slightly lower as compared to sapphire substrates, suggesting similar high-temperature growth as sapphire, typically in the range of 850 °C-950 °C, that can be used for the growth of β-GaO on SiC.

Epitaxial Growth of (-201) β-GaO on (001) Diamond Substrates.

Heteroepitaxial growth of β-GaO on (001) diamond by metal-organic chemical vapor deposition (MOCVD) is reported. A detailed study was performed with Transmission Electron Microscopy (TEM) elucidating the epitaxial relation of (-201) β-GaO||(001) diamond and [010]/[-13-2] β-GaO ||[110]/[1-10] diamond, with the presence of different crystallographically related epitaxial variants apparent from selected area diffraction patterns. A model explaining the arrangement of atoms along ⟨110⟩ diamond is demonstrated with a lattice mismatch of 1.

Composition and strain relaxation of In Ga N graded core-shell nanorods.

Two In Ga N nanorod samples with graded In compositions of x = 0.5-0 (Ga-rich) and x = 0.5-1 (In-rich) grown by molecular beam epitaxy were studied using transmission electron microscopy.

Managing dose-, damage- and data-rates in multi-frame spectrum-imaging.

As an instrument, the scanning transmission electron microscope is unique in being able to simultaneously explore both local structural and chemical variations in materials at the atomic scale. This is made possible as both types of data are acquired serially, originating simultaneously from sample interactions with a sharply focused electron probe. Unfortunately, such scanned data can be distorted by environmental factors, though recently fast-scanned multi-frame imaging approaches have been shown to mitigate these effects.

Observation of antisite domain boundaries in Cu2ZnSnS4 by atomic-resolution transmission electron microscopy.

Atomic resolution transmission electron microscopy has been used to examine antisite defects in Cu2ZnSnS4 (CZTS) kesterite crystals grown by a hot injection method. High angle annular dark field (HAADF) imaging at sub-0.1 nm resolution, and lower magnification dark field imaging using reflections sensitive to cation ordering, are used to reveal antisite domain boundaries (ADBs).