Department of Physics
Condensed Matter Seminar

Photon detectors have many important applications, such as in heat sensing, digital cameras, solar cells and x-ray and gamma-ray detection. So far, the most common detectors are based on elemental semiconductors , such as Si and Ge. However, they are by no means perfect in tackling some of the important problems facing the modern society. For example, thin films solar cells are not yet as economical as coal/gas fired power generators. For homeland security applications, high energy radiation detectors are too bulky and require cryogenic cooling. In this talk I shall describe a joint effort between theorists and experimentalists at Berkeley to look for new semiconductor detectors with better performance than existing detectors. On the experimental side, combinatorial techniques are utilized to allow for fast growth and characterization of a large library of new semiconductors synthesized by laser ablation. On the theory front, computational techniques are developed to allow for the prediction of all the properties of semiconductors relevant to photon detection. By “all”, we mean electronic, optical, vibrational, transport, magnetic and defect properties. While this ambitious project is still in progress, I shall describe some new and interesting results we have found in the well-studied zincblende- and wurtzite-type semiconductors. We have obtained new insights into the effects of transition and rare-earth metal dopants, such as Cu and Gd, on the transport and magnetic properties of the host semiconductor.