(Invited) Chalcogenide Glasses for Planar Devices

Semiconducting chalcogenide glasses (ChGs) are well known for their amenability to film fabrication and intriguing optical properties, namely transparency in key mid-infrared wavelength regimes where target analytes have fundamental molecular fingerprints. To realize next generation photonic sensing devices, high production and low cost is sought by leveraging the existing capabilities and knowledge-base of microelectronics, such as through the compositional design of materials that are compatible with CMOS manufacturing techniques. Subsequent improvements in overall device performance through reduced optical loss, and increased accuracy, sensitivity, and specificity enables these sensors to rival the capabilities of larger and costlier sensing technologies such as Fourier transform infrared (FTIR) spectroscopy. Thus, ChGs are poised to play a leading role in miniaturized chemical sensing technology, which is enabled through various techniques of film deposition on Si substrates and post-processing to precisely fabricate micron-scale structures and components. Amongst these techniques, this presentation highlights recently developed 2-D and 3-D printing of ChG films from solution by electrospray, a process which is compatible with continuous manufacturing, engineered non-uniform thickness films, and direct writing of coatings with compositional gradients. In addition, this work has also advanced the controlled crystallization of both bulk and film forms of ChG by laser exposure and heat treatment, which allows further tunability of the material properties and an additional strategy to obtaining spatial gradients in material properties. This presentation will discuss the development of the ChG materials processing “toolbox” in light of the oncoming maturation of microphotonic chemical sensors.