Based on a virtual GaN substrate approach on Si(111) by a step graded double oxide (Sc2O3/Y2O3) buffer, we report a “proof of principle” study on the enhanced photo-response of ultraviolet GaN photo-detectors due to embedded DBRs (distributed Bragg reflectors). Embedded DBRs benefit from an order of magnitude lower number of superlattice sequences in contrast to III- nitride systems due to the high refractive index contrast between high-k Y2O3 and low-k Si. The UV (ultraviolet) reflectance efficiency of the designed DBR is proven by a considerable photo-response increase in the UV range in comparison to reference GaN layers on Si(111) without DBRs.

Based on a novel double step oxide buffer heterostructure approach for GaN integration on Si, we present an optimized Metal-Semiconductor-Metal (MSM)-based Ultraviolet (UV) GaN photodetector system with integrated short-period (oxide/Si) Distributed Bragg Reflector (DBR) and leakage suppressing Metal-Oxide-Semiconductor (MOS) electrode contacts. In terms of structural properties, it is demonstrated by in-situ reflection high energy electron diffraction and transmission electron microscopy-energy dispersive x-ray studies that the DBR heterostructure layers grow with high thickness homogeneity and sharp interface structures sufficient for UV applications; only minor Si diffusion into the Y2O3 films is detected under the applied thermal growth budget. As revealed by comparative high resolution x-ray diffraction studies on GaN/oxide buffer/Si systems with and without DBR systems, the final GaN layer structure quality is not significantly influenced by the growth of the integrated DBR heterostructure. In terms of optoelectronic properties, it is demonstrated that—with respect to the basic GaN/oxide/Si system without DBR—the insertion of (a) the DBR heterostructures and (b) dark current suppressing MOS contacts enhances the photoresponsivity below the GaN band-gap related UV cut-off energy by almost up to two orders of magnitude. Given the in-situ oxide passivation capability of grown GaN surfaces and the one order of magnitude lower number of superlattice layers in case of higher refractive index contrast (oxide/Si) systems with respect to classical III-N DBR superlattices, virtual GaN substrates on Si via functional oxide buffer systems are thus a promising robust approach for future GaN-based UV detector technologies.

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Various (Au, Pt, Ir) M-S and M-O-S type contact to N-polar GaN layer on Si(111) via oxide buffers were fabricated and characterized. The influence of rapid thermal annealing processes on electrical properties and contact morphology was examined. Iridium based contacts, annealed in 700 °C, exhibit lowest dark current (Φ B = ~1.1 eV) and are thus identified as most suitable for UV photodetector applications.

Graphene is in focus of intensive efforts to revolutionize high‐frequency microelectronic applications. Many fascinating ideas relying on the unique properties of graphene have been developed in research laboratories. Among the hindrances on the way to mass production is the lack of compatibility between the existing methods to grow graphene and the practical requirements of silicon mainstream technology. Although these problems are likely to be alleviated if no other solution is found, of major interest remains a search for a method to grow graphene film directly in the device area where it is needed. This graphene film does not necessarily have to cover area much larger than the active region of the device, but high quality of the film and metal‐free growth on an insulating substrate below 1000 °C are important. Lippert et al. (pp. ) demonstrate direct growth of high quality graphene on insulators at moderate temperatures by molecular beam epitaxy. The quality of the graphene indicates a negligible density of defects. These results are combined with insights from density functional theory calculations. The authors discuss the growth mechanism on mica and similar (i.e., SiO2‐terminated) substrates.