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Engineering semiconductors using energetic beams

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Date and time Mar 12, 2009
from 04:00 PM to 05:00 PM
Location McLennan Physics (MP) 102
Host Kenneth Burch

Oscar Dubon

Abstract:

Colloq Mar12Alloying is a well-established method used to tailor the electrical and optical properties of semiconductors.  Control over the energy band gap of a material, or so-called band gap engineering, via alloy composition lies at the heart of today's most advanced quantum-well devices.  For the vast majority of alloy systems, producing the desired changes in properties requires alloying levels well beyond several atomic percent and thus the use of advanced thin-film deposition techniques.  However, recently a new class of novel compound semiconductors has emerged for which fundamental properties are dramatically modified through the substitution of a relatively small fraction of host atoms with a very different element.  At Berkeley we have developed a combination of ion implantation and pulsed-laser melting to synthesize these diluted semiconductor alloys.  While ion implantation enables the injection of high concentrations of a species into a semiconductor, radiation from an excimer laser pulse melts the ion implanted layer, which subsequently crystallizes on time scales on the order of 10-7 seconds.  I will discuss our efforts to apply this simple technique for the realization of new semiconductors for applications in photovoltaics and spintronics.

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