Paper TF-ThP44
Water Cooled Low Temperature Evaporation (LTE) Source for Thin Film Organic Semiconducting Materials

Thursday, November 10, 2016, 6:00 pm, Room Hall D

Rapid advances in research and development in organic electronics have resulted in many exciting discoveries and applications, including organic light-emitting devices for information display and illumination, solar cells, photodetectors, chemosensors, and logic devices. Organic semiconducting materials are broadly classified as polymeric or small molecular. For the latter category, solvent-free thin film deposition techniques are generally preferred to form well-defined interfaces and improve device performance. Controlled deposition of organic semiconductor materials has become more and more important. Due to lower process temperatures (up to ~500C), the manufacturing of organic electronic devices such as light emitting diodes (OLEDs) and other electronic devices is less energy consuming than conventional silicon based electronics. Additionally, these low temperatures also make it possible to use flexible substrates, e.g. plastic films, which can serve as a basis for elastic electronic devices. The crucial part of the fabrication is the deposition of the active organic layers (films) with a layer thickness between 10 and 100 nanometres. It is mostly done by thermal evaporation in a high vacuum environment. The mobility of the charge carriers within the layers and the layer morphology strongly depend on the deposition rates, i.e. the increase in layer thickness with time during the deposition process. The desired deposition rates range between 0.01 and 5 Angstrom per second.

Kurt J. Lesker Company has developed thin film LTE deposition sources which can deposit a wide range of organic materials with precise deposition rates and thickness control. These sources can be coupled with quartz crystal monitors (QCM) and closed loop PID control systems to ensure consistent high-quality results. The process can be performed at very high levels of vacuum allowing for a long mean free path and therefore lower tendency to introduce film impurities. High deposition rates can be achieved and lower energy particles can reduce substrate damage. Low temperature evaporation sources can take hours to cool in a vacuum system before venting is possible to replenish. This increases device fabrication tact times, reduces throughput and creates the need for more sources in larger platforms. Kurt Lesker’s water cooled LTE source has the ability to cool down 3.7x times faster against the standard LTE source, saving precious time while maintaining precise thin film growth during deposition process.