Past Events

Abstract:

In a world running out of energy on one hand and facing terrorists threat every day, there is urgent need to find better detector for photons with energy ranging from the infrared to gamma ray. So far semiconductors are the only candidates which can fill the need for such wide-range of photon energies. One example is high quality Si single crystals but Si has serious shortcomings. For example, Si solar cells are not the most efficient ones while Si x-ray and gamma-ray detectors have to operate at low temperature making them unwieldy for large scale applications. In this talk I will describe a combined experimental and theoretical effort initiated at Berkeley to explore a large number of unconventional semiconductor alloys for photodetectors. On the experimental side a combinatorial fabrication technique based on pulsed laser deposition is used to grow large libraries of alloys which cannot be grown under equilibrium conditions. The optical, structural, transport and defect properties of such alloys are computed with first-principle density-function techniques for comparison with experiment. Examples from Group V, III-V and II-VI semiconductors will be presented.

Coffee and tea will be served 20 minutes prior to the seminar.