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Metal-halide perovskites are promising lasing materials for the realization of monolithically integrated laser sources, the key components of silicon photonic integrated circuits (PICs). Perovskites can be deposited from solution and require only low-temperature processing, leading to significant cost reduction and enabling new PIC architectures compared to state-of-the-art lasers realized through the costly and inefficient hybrid integration of III−V semiconductors. Until now, however, due to the chemical sensitivity of perovskites, no microfabrication process based on optical lithography (and, therefore, on existing semiconductor manufacturing infrastructure) has been established. Here, the first methylammonium lead iodide perovskite microdisc lasers monolithically integrated into silicon nitride PICs by such a top-down process are presented. The lasers show a record low lasing threshold of 4.7 μJcm–2at room temperature for monolithically integrated lasers, which are complementary metal–oxide–semiconductor compatible and can be integrated in the back-end-of-line processes.

The unique behavior of colloids at liquid interfaces provides exciting opportunities for engineering the assembly of colloidal particles into functional materials. The deformable nature of fluid–fluid interfaces means that we can use the interfacial curvature, in addition to particle properties, to direct self-assembly. To this end, we use a finite element method (Surface Evolver) to study the self-assembly of rod-shaped particles adsorbed at a simple curved fluid–fluid interface formed by a sessile liquid drop with cylindrical geometry. Specifically, we study the self-assembly of single and multiple rods as a function of drop curvature and particle properties such as shape (ellipsoid, cylinder, and spherocylinder), contact angle, aspect ratio, and chemical heterogeneity (homogeneous and triblock patchy). We find that the curved interface allows us to effectively control the orientation of the rods, allowing us to achieve parallel, perpendicular, or novel obliquely orientations with respect to the cylindrical drop. In addition, by tuning particle properties to achieve parallel alignment of the rods, we show that the cylindrical drop geometry favors tip-to-tip assembly of the rods, not just for cylinders, but also for ellipsoids and triblock patchy rods. Finally, for triblock patchy rods with larger contact line undulations, we can achieve strong spatial confinement of the rods transverse to the cylindrical drop due to the capillary repulsion between the contact line undulations of the particle and the pinned contact lines of the sessile drop. Our capillary assembly method allows us to manipulate the configuration of single and multiple rod-like particles and therefore offers a facile strategy for organizing such particles into useful functional materials.

In this study, the impact of impurities incorporated into plated nickel seed layer on silicide formation and the influence of annealing temperature on the fill-factor (FF) loss of solar cells with Ni-Cu contacts is investigated. The silicide growth of electroless plated nickel seed layer is significantly retarded compared with literature data on physical-vapor-deposition (PVD)-based nickel annealed at 550 °C. X-ray photoelectron spectroscopy and X-ray diffraction reveal the presence of SiO2 at the Ni-Si interface and the formation of nickel phosphides in addition to nickel silicide. The retardation in silicide growth is attributed to the presence of (111) planes after the texturing process and contaminants in the seed layer. Varying the annealing temperature of fabricated cells from 350 °C to 425 °C led to a decrease in the average FF from 79.3% to 77.5%. The loss analysis is based on Suns-V oc measurements, illuminated current-voltage parameters, and dark current-voltage curve fitting based on a three-diode model. It reveals that the FF loss is dominated by increased junction recombination, whereas losses due to third-diode component become significant for annealing at 400 °C and higher temperatures. The results highlight the need to carefully tune the seed layer annealing parameters to the interface conditions and junction depth of solar cells.

Comparative structural analyses of a crystallized, 60 nm thick silicon film deposited on quartz substrate were performed using high resolution transmission electron microscopy (HRTEM) and Raman spectroscopy (RS). Both methods suggest high degree of crystallization of the film. The material of the film consists of crystalline grains with sizes up to 20 nm (HRTEM) and the mean size of the grains is ∼4 nm (RS). HRTEM results suggest large scatter of the crystal orientations of the grains. The existence of boundary defects between grains grouped in large agglomerates was also detected by HRTEM. RS analyses indicate large compressive strain in the system and the existence of high pressure Si phases in the material of the film.