Organic Molecular Beam Deposition

OMBD is a method to fabricate thin films. By this procedure molecules are evaporated from a reservoir and condensed on a substrate. OMBD, which is performed in ultrahigh vacuum, has several advantages. For example, a high pureness of the evaporated material can be obtained and a clean surface of the substrate warranted. For OMBD a reservoir of molecules is heated up to a temperature at which the molecules sublime into the gas phase. By the geometry of the crucible (typical Al or quartz) they are directed to the surface of interest. This is accomplished using Knudsen effusive cells in which a cylindrical crucible with specific aspect ratios is heated by means of a heating coil. Thereby, the temperature of the cells is fine regulated in such way that the intended deposition rate is obtained controlling the film growth and molecules orientation. The deposition rate is monitored by a quartz crystal microbalance.