Publications by authors named "J J Mark Haverkort"

Hexagonal Si Ge with suitable alloy composition promises to become a new silicon compatible direct bandgap family of semiconductors. Theoretical calculations, however, predict that the binary end point of this family, the bulk hex-Ge crystal, is only weakly dipole active. This is in contrast to hex-Si Ge , where translation symmetry is broken by alloy disorder, permitting efficient light emission.

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Silicon is indisputably the most advanced material for scalable electronics, but it is a poor choice as a light source for photonic applications, due to its indirect band gap. The recently developed hexagonal SiGe semiconductor features a direct bandgap at least for x > 0.65, and the realization of quantum heterostructures would unlock new opportunities for advanced optoelectronic devices based on the SiGe system.

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Monolithic integration of silicon-based electronics and photonics could open the door toward many opportunities including on-chip optical data communication and large-scale application of light-based sensing devices in healthcare and automotive; by some, it is considered the Holy Grail of silicon photonics. The monolithic integration is, however, severely hampered by the inability of Si to efficiently emit light. Recently, important progress has been made by the demonstration of efficient light emission from direct-bandgap hexagonal SiGe (hex-SiGe) alloy nanowires.

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The use of gas diffusion electrodes that supply gaseous CO directly to the catalyst layer has greatly improved the performance of electrochemical CO conversion. However, reports of high current densities and Faradaic efficiencies primarily come from small lab scale electrolysers. Such electrolysers typically have a geometric area of 5 cm, while an industrial electrolyser would require an area closer to 1 m.

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Recently synthesized hexagonal group IV materials are a promising platform to realize efficient light emission that is closely integrated with electronics. A high crystal quality is essential to assess the intrinsic electronic and optical properties of these materials unaffected by structural defects. Here, we identify a previously unknown partial planar defect in materials with a type basal stacking fault and investigate its structural and electronic properties.

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