Here we present variouse instruments that are currently in use in our group.
The DBLI allows a variety of ferroelectric measurements between -196°C and 600°C. Apart from purely electrical characterization, the laser interferometer also enables a quantitative measurement of the piezoelectrical coefficient. The Linkam Temperature Control stage permits quick temperature change and can also be used outside the DBLI for other experiments.
The fabrication of organic solar cells, transistors or thermal generators often involves oxygen and/or moisture sensitive materials. In order to prevent degradation, these materials need to be processed inside of so-called gloveboxes that maintain an inert nitrogen gas atmosphere (O2 and H2O <1ppm).
There are two glovebox systems (GS Glovebox Systemtechnik) available inside the cleanroom, one for solution-based processing and the other for thin film deposition via thermal evaporation. The former is equipped with two spin-coaters, several hotplates, and a microbalance with an ionizer and the latter houses two thermal evaporators (Mantis Deposition LTD), which are integrated into the cleanroom wall. One evaporator is designed for the deposition of metals and other contact materials (Al, Ca, MoO3, Au, Ag, Cr, LiF, etc.) and the other one is used of organic materials (Pentacene, C60, CBP, TAPC, NPB, BCP etc.). Both evaporators feature six sources, rotating substrate holders, and can be loaded and operated from inside the cleanroom as well as from outside the service corridor.
The thermal metallic evaporator (Mantis Deposition LTD Evaporator) allows for evaporation and thus deposition on substrates of metals such as gold, aluminum, chromium and silver. The evaporation takes place via heating of evaporation boats in which the material resides. Both manual and rate-controlled evaporation procedures are possible.
The organic evaporator can autonomously monitor and control the temperature of each source, enabling the co-deposition of up to three materials with individual evaporation rates. Additionally, it is possible to heat up to sample holder to improve the crystallisation process of the deposited thin film.
The probe stations are used for electric characterization of samples. The contact needles allow for both out-of-plane and in-plane devices to be investigated. The air probe station is mostly used for ferroelectric characterization under atmosphere conditions. The vacuum probe station allows for electric and dielectric measurements under vacuum. Furthermore, the samples can be cooled down to temperatures as low as 70 K via usage of fluid nitrogen.
Atomic force microscopy (AFM) is an imaging technique that measures the topology of a surface with nanometre height resolution, based on the detection of local forces acting between a sharp tip and the sample. Measurements can be made in tapping or contact mode. The setup be extended to do piezoelectric force microscopy as well.
This fully automatized and straight-forward setup allows for coating of substrates with solutions. The dip-coater is located in a closeable box which isolates the coating process from external atmospheric changes. Dip-coating is known for its well-controlled and reproducible production of aligned films. The aligned deposition of the material is possible due to broken symmetry at the vapour-substrate-liquid interface. The aligned films can and are used for further experiments.
Based on the monochromatic light output of a Perkin-Elmer Lambda 1050+ UV-Vis-IR-spectrophotometer, this setup measures the extraction yield of photogenerated charge carriers of organic solar cells in the wavelength range between 400 and 2500 nm. By utilizing sensitive amplification and lock-in techniques - further optimized by electrical noise analyses - we are able to obtain a dynamic range of up to 10 orders of magnitude in external quantum efficiency spectra. The experiment is completed by sources for both light- and DC voltage biasing, and a Linkam HFS600 cryo-probe-stage to extend the temperature range from -195°C to 200°C.
The LABCOTER™ (PDS 2010, Specialty Coating Systems Inc.) is a parylene deposition system used to prepare uniform and pin-hole free parylene layers via chemical vapour deposition. Parylene layers are formed directly and conformally on any substrate in a two temperature step program (~250 °C and ~600 °C) inside a high-vacuum chamber. Layer thicknesses are determined by the amount of loaded parylene dimers (precursor) and can range from a few nm to a few μm.
The ST-100 cryostat from Lake Shore Cryotronics allows for fast and efficient cooling of samples down to 77K and heating up to 500K. It is equipped with four probe needles that are wired to BNC-connections enabling all kinds of electrical measurements. The vacuum shroud possesses four windows which can be used for sample illumination and possibly optical reflection measurements.
