Thermal model of Knudsen cells for organic molecular beam deposition

Knudsen cells used for molecular beam deposition of organic materials are u sually derived from the ones employed for conventional epitaxy of inorganic semiconductors. However, organic molecular materials need rather low evapo ration temperatures and a very precise temperature control in the range fro m 100 to 400 degreesC. Therefore, a thermal model of the cell is needed, wh ich, taking into account the peculiarity of organic molecular beam depositi on, gives the thermal dynamics of the cell and can be used for developing a ccurate algorithms for thermal programming and control. In this article suc h a model is developed and fully assessed through a comparison with experim ental results; on this basis, all information necessary fur precisely contr olling and programming Knudsen cells for organics is obtained. (C) 2001 Ame rican Vacuum Society.