Princeton University

School of Engineering & Applied Science

Solution-Processing of Chalcogenide Materials for Device Applications

Yunlai Zha
Engineering Quadrangle J401
Friday, May 9, 2014 - 9:15am to 11:00am

Chalcogenide glasses are well-known for their desirable optical properties, which have enabled many infrared applications in the fields of photonics, medicine, environmental sensing and security. Conventional deposition methods are efficient for fabricating structures on flat surfaces, but have limitations in deposition on curved surfaces, deposition of thick layers and component integration. In these cases, solution-based methods, which involve the dissolution of chalcogenide glasses and processing as a liquid, become a better choice for their flexibility. After proper treatment, the associated structures can have similar optical, chemical and physical properties to the bulk.
 This thesis presents an in-depth study of solution-processing chalcogenide glasses, starting from the "solution state" to the "film state" and the "structure state". Firstly, chalcogenide dissolution and the thermal processing are studied to reveal the mechanisms and build a foundation for material processing. Secondly, thermal processing, in the context of high temperature annealing, is explained along with the chemical and physical properties of the annealed films. In addition, we thoroughly characterize the pore formation phenomenon and propose a theory for the process. Thirdly, several solution methods developed along with the associated photonic structures are demonstrated, including a first demonstration of thick chalcogenide deposition by lamination, chalcogenide waveguides deposition on curved surfaces and solution-processed chalcogenide waveguides of the lowest loss. These results contribute to the advancement of chalcogenide processing technologies and help move closer towards the ultimate goal of fabricating reliable IR sensors.