Future success of diamond-based high-power electronic devices critically depends on the availability of wafer-size single crystals. For their realization, heteroepitaxy on iridium is currently the most promising approach in terms of scalability. However, in contrast to homoepitaxial deposition on carefully selected seed crystals, heteroepitaxial diamond layers generally start with a dislocation density of more than 10¹⁰ cm⁻² and its efficient reduction is the main issue for the subsequent growth of thick high-quality layers. In the Feature Article by M. Schreck et al. (pp. 2028–2035), several different aspects of dislocations in the CVD growth of diamond films are discussed. They comprise the mutual interaction among dislocations, their interaction with the growth surface, the decisive role of dislocations in the formation of growth stress and their role as sinks for dopant atoms. The results provide valuable insights for further efforts in material improvement and the control of stress during film growth. The cover image shows the reduction of dislocation density within the first 1000 ìm of growth and a 4-inch diamond/Ir/YSZ/Si(001) wafer after diamond nucleation and several micron growth. Various cuboids and discs with diameters of up to several centimeters in the background are products synthesized by this technique (www.audiatec.de).

Among diamond's many unusual properties is the ability to act as a negative electron affinity material. While electron emission from diamond has been heavily studied in vacuum, recent work by Hamers and co-workers has shown that diamond can also act as a solid-state emitter of electron in liquids. In their article on pp. 2069−2074, Hamers and Bandy explore the direct emission of electrons into atmospheric-pressure gases, using argon, air, and SF₆ as model systems. In contrast to the more commonly used hydrogen-terminated diamond, amineterminated diamond provides a fixed positive surface charge that helps to effectively extract electron from the bulk. Electrons emitted into air and into SF₆ can form stable anions (O₂ – and SF₆ –), leading to electron emission currents controlled by the ion mobilities. In contrast, argon does not form a stable anion, so electrons transported through argon gas are transported as free electrons, albeit subject to frequent scattering events. This work provides new insights into the nature of electron emission from diamond and extends its use as a solid-state emitter of electrons in ambient environments.

The authors report on a facile, rapid, and calibration-free method to extract automatically the thickness of CH₃NH₃PbI₃ nanowire thin-films on dielectric surfaces directly from optical images. Their method amounts to minimize a suitable defined distance in the red-green-blue color space which measures the difference between the observed and calculated colors of perovskite nanowires.