Yttria-stabilized zirconia (YSZ) is a well-known solid electrolyte material in high-temperature applications that involve the conduction of oxygen ions. One possible way of enhancing the performance of devices like solid oxide fuel cells at lower operation temperatures is the design of the electrolyte’s surface by increasing the surface area and modifying the surface properties by ceria coating to improve the oxygen incorporation reaction. However, the preparation of a conformal coating while maintaining a complex surface morphology on the nanoscale is challenging employing conventional evaporation methods. In this work we present thin ceria coatings (9–20 nm) that were deposited on porous 8 mol % YSZ thin films using atomic layer deposition (ALD). The YSZ films (with thicknesses between 90 and 130 nm) were prepared using pulsed laser deposition at various substrate temperatures, thus leading to different surface morphologies. The investigation of the sample cross section by high angle annular dark field transmission electron microscopy exhibits columnar growth of epitaxial grown ceria thin films with excellent coating conformity. This demonstrates the great potential of the ALD process for surface modification of porous materials, where controlled and conformal coating of high surface areas is desired.

Cubic nitrides are candidate materials for next-generation optoelectronic applications as they possess no internal fields and promise to cover large parts of the electromagnetic spectrum from the deep UV toward the mid-infrared. Their successful application demands high-quality epitaxial growth of c-GaN as a base material. This infers a virtually perfect crystallinity as well as smooth surfaces and interfaces despite the limited availability of suitable substrate materials. Here, we systematically introduce pre-growth treatments and c-AlN buffer layers to optimize c-GaN epitaxial layers. Optimized growth parameters yield extremely small surface roughness values below 1 nm root mean square of phase pure c-GaN layers with very limited stacking fault densities as highlighted by scanning transmission electron microscopy. The crystallinity is monitored by X-ray diffraction and surpasses the current standards. We study the effects of the pre-growth procedures on the optical response by photoluminescence spectroscopy and reconfirm the high structural quality of the epitaxial layers. The combined optimization of all layer properties through the universally applicable approach allows for the growth of more complex quantum structures toward device applications.

Electrical transport in metal spinel ferrites (MFe2O4, M = transition, earth-alkali, or main group divalent metal) arises from charge carrier hopping between octahedral sites of different oxidation state. This allows...

Cubic InxGa1-xN alloys are a candidate material for optoelectronic applications because they lack internal polarization fields and promise to cover a vast range of emission wavelengths. However, the large discrepancy in interatomic spacing and growth temperatures of c-GaN and c-InN hinder InxGa1-xN-growth. We report cubic InxGa1-xN layers grown by plasmaassisted MBE and achieve continuous miscibility of the indium content x(In) over the whole composition range. X-ray diffraction precisely monitors the composition, phase purity and miscibility of the thin films. Furthermore, we discuss the impact of the indium content on the crystallinity. Complementary, low-temperature photoluminescence studies elucidate the optical response of cubic InxGa1-xN layers.

Cubic nitrides are candidate materials for next-generation optoelectronic applications as they lack internal fields and promise to cover large parts of the electromagnetic spectrum from the deep UV towards the mid infrared. This demands high-quality epitaxial growth of c-GaN as base material. We demonstrate the influence of pre-growth treatments and c- AlN buffer layers on the quality of c-GaN grown on 3C-SiC/Si substrates by molecular beam epitaxy (MBE). Optimized parameters yield extremely small surface roughness values below 1 nm of phase pure c-GaN layers with very limited stacking fault densities. Structural properties have been studied by X-ray diffraction and atomic force microscopy and surpasses the current standards, which allows for growth of more complex quantum structures for device application.