The ORMA has six pockets which can be independently controlled to achieve simultaneous co-evaporation of several organic materials. The high degree of control inherent to the design of the source enables the deposition of organic coatings from submonolayer range to continuous films.
The general concept of ORMA operation can be described as follows. The evaporant is placed inside a quartz crucible surrounded by a filament. The heating of the crucible is achieved by passing an electrical current through the filament and generating radiative heat, which in turn heats the evaporation material. ORMA provides continuous heating of material up to 600°C.
The temperature of the material in each pocket is individually monitored by a thermocouple (type K). The thermocouple signal is fed into a PID controller, which maintains a constant temperature in the crucible and creates a constant flux of evaporated material from the source towards the substrate. The ORMA design ensures precise and reproducible temperature control, which is essential for organic material evaporation.
The ORMA is optimised for evaporation over a temperature range of 50°C to 600°C and its temperature stability at optimal PID settings is better than 0.05°C.
The entire source assembly is water cooled in order to avoid any temperature cross-talk between the individual crucibles. The water cooling of the ORMA source has proven to be very efficient even when operating for extended periods of time at high powers, resulting in a negligible effect on the chamber base pressure.
The crucible capacity is 6 x 60mm3, which makes the ORMA source suitable for the deposition of thin films and functionalization of surfaces. The unique design of the crucible allows an in-situ exchange of crucibles using a wobblestick without breaking vacuum.
The ORMA crucible is made out of quartz, which is an excellent inert container that ensures no chemical reaction with the organic evaporant. In addition, quartz works reliably even at high temperatures exceeding 600°C with very little outgassing.
The source is designed to be fully serviced in the field. The head of the instrument has no brazed ceramics which can be broken or coated and the filament assembly can be easily accessed for a quick exchange.