Chalcogenide phase change materials reversibly switch between non-volatile states with vastly different optical properties, enabling novel active nanophotonic devices. However, a fundamental understanding of their laser-switching behavior is lacking and the resulting local optical properties are unclear at the nanoscale. Here, we combine infrared scattering-type scanning near-field optical microscopy (SNOM) and Kelvin probe force microscopy (KPFM) to investigate four states of laser-switched Ge 3 Sb 2 Te 6 (as-deposited amorphous, crystallized, reamorphized, and recrystallized) with nanometer lateral resolution. We find SNOM to be especially sensitive to differences between crystalline and amorphous states, while KPFM has higher sensitivity to changes introduced by melt-quenching. Using illumination from a free-electron laser, we use the higher sensitivity to free charge carriers of far-infrared (THz) SNOM compared to mid-infrared SNOM and find evidence that the local conductivity of crystalline states depends on the switching process. This insight into the local switching of optical properties is essential for developing active nanophotonic devices.

In the family of functional oxide materials, the interface between LaAlO 3 and SrTiO 3 (LAO/STO) is an interesting example, as both materials are largebandgap insulators in their bulk state but give rise to a confined 2D electron gas (2DEG) when combined through thin-film deposition. While this 2DEG exhibits remarkable properties, its experimental investigation is mostly limited to destructive or non-local (i.e. averaging over larger areas) methods until recently. Scanning near-field optical microscopy is shown to overcome this limitation, detecting buried 2DEGs by using highly confined optical nearfields. Here, a full spectroscopic approach with phonon-enhancement and simulations based on the finite dipole model is combined to extract quantitative electronic properties of the interfacial LAO/STO 2DEG. This threefold improvement compared to previous work will enable the quantitative nanoscale, non-destructive, sub-surface analysis of complex oxide thin films and interfaces, as well as similar heterostructures.

No abstract

No abstract

Herein, we report on a newly developed and commercialized organic photo-curable Nanoimprint Lithography (NIL) resist, namely mr-NIL210. Since this new NIL resist follows an innovative design concept and contains solely specific monomers with a characteristic chemistry and molecular design, an extended longevity of applied polydimethyl siloxane (PDMS) stamps is enabled addressing a crucial key metric for industrial high-volume manufacturing processes. Moreover, the mr-NIL210 is characterized by a negligible oxygen sensitivity of the curing chemistry, outstanding film forming and adhesion performances as well as excellent plasma-based dry etch characteristics for various substrate materials like silicon, aluminum, sapphire, titanium, etc.