Novel Quaternary Semiconductor Materials: Growth and Characterization

Quaternary materials have a large flexibility to design bandgap and effective performance for detectors. In the ternary and quaternary chalcogenides, the semiconducting to seminsulating properties are exhibited with bandgaps from narrow (<1 eV) to large (>3 eV) and have the potential and flexibility to produce large numbers of electron hole pairs and hence increase detector sensitivity. In this paper we describe the Ag-Ga-Ge-Se class of materials, an extension of the In-GaSe system, and the challenges related to the material. The important material in this class is the AgGaGe₃Se₈ stoichiometry. A comprehensive solution to produce its derivatives and experimental results are presented. These are compared with the In-GaSe class of materials for growth and fabrication which we have developed over many years. We have developed processes for purification, synthesis of large batches of materials, and crystal growth by vertical Bridgman method. These crystals are grown by both capillary seeding and oriented seeding. The details of the growth process, X-ray orientation, cutting, polishing, fabrication and stability of the large size crystals will be presented.