Phase transitions in a non-monodisperse dusty plasma

Summary form only given. In semiconductor manufacturing, contamination due to particulates significantly decreases the yield and quality of device fabrication, therefore increasing the cost of production. Dust particle clouds can be found in almost all plasma processing environments including both plasma etching devices and plasma deposition processes. Many experiments have been conducted over the past decade on such colloidal plasmas in an attempt to discover the character of the systems formed, but additional work is needed in order to fully understand the physics behind these structures. The majority of complex plasma experiments to date have employed monodisperse spheres when forming ordered dusty plasma systems. However, in the majority of plasma processing environments the particle size distributions are obviously more randomized and disperse. This paper reports experiments carried out in a GEC rf reference cell modified for use as a complex plasma system. Non-monodisperse particles were used to determine the manner in which phase transitions and other thermodynamic properties depend upon the overall dust grain size distribution. Two dimensional (2D) plasma crystals were formed in an Argon plasma using assorted glass spheres with specific size distributions. Employing various, standard optical techniques, the pair correlation function was then determined for different pressures and powers and compared to measurements obtained for monodisperse spheres.