Material transport regimes and mechanisms for growth of molecular organic thin films using low-pressure organic vapor phase deposition

We determine the physical mechanisms controlling the growth of amorphous or ganic thin films by the process of low-pressure organic vapor phase deposit ion (LP-OVPD). In LP-OVPD, multiple host and dopant molecular sources are i ntroduced into a hot wall reactor via several injection barrels using an in ert carrier gas, allowing for controlled film growth rates exceeding 10 Ang strom /s. The temperature and carrier flow rate for each source can be inde pendently regulated, allowing considerable control over dopant concentratio n, deposition rate, and thickness uniformity of the thin films. The rate of film deposition is limited either by the rate of condensation on the subst rate or by the rate of supply from the source. The source-limited regime ca n be further classified into equilibrium or kinetically limited evaporation , coupled to convection- or diffusion-limited deposition. Models are develo ped to relate the rate of film growth to source and substrate temperature, and carrier gas flow rate. These models characterize and predict the perfor mance of the LP-OVPD system used to grow high performance organic light emi tting devices. (C) 2001 American Institute of Physics.