Advanced Materials

Dopant Electromigration in Semiconductors

Authors

  • Prof. David Cahen,

    1. Department of Materials and Interfaces Weizmann Institute of Science 76100 Rehovot (Israel)
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    • David Cahen, born and raised in Holland, completed his B.Sc. in chemistry at the Hebrew University of Jerusalem and his Ph.D. in materials chemistry at Northwestern University, USA, after which he returned to Israel as a Weizmann fellow, working on the biophysics of photosynthesis. In 1976 he joined the Weizmann Institute and started research on semiconductor photoelectrochemical solar cells and photoacoustic studies of energy conversion processes. This led to the work reported in this review as well as ongoing studies on the chemical limits of device miniaturization. In addition, he is working on extending and fine-tuning semiconductor properties and on the materials and surface chemistry of photovoltaic solar cells.

  • Dr. Leonid Chernyak

    1. Department of Materials and Interfaces Weizmann Institute of Science 76100 Rehovot (Israel)
    Current affiliation:
    1. Intel Corp., 2200 Mission College Blvd., Santa Clara, CA 95052-8119, USA.
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    • Leonid Chenyak is a member of the technical staff at Intel Corp, working on flash memory technology. He grew up in Lvon, Ukraine, where he studied electrical engineering at Lvov Technical University, receiving his M.Sc. in 1986. He worked for several years in industry before emigrating to esrael in 1990. There he joined the Weizmann Institute as a Ph.D. student, completing his thesis in 1996. He then worked as a postdoctoral fellow at Colorado State University and Texas Tech, concentrating on the optical and electronic properies of GaN and GaP. He will move to Intel's new Kiryal Gut (Israel) fabrication unit upon completion of his training.


  • Our work that is reviewed here was supported by grants from the US-Israel binational science foundation, Jerusalem, Israel, the EU-Israel cooperative research programme, the israel science foundation, the german-israel science foundation, and the minerva foundation, Munich.

Abstract

A doped semiconductor can be viewed as a mixed electronic-ionic conductor, with the dopants as mobile ions. Normally the temperature range where this becomes true is not even close to that where the (opto)electronic properties of the material are of interest. However, notable exceptions exist and these are reviewed here, with special emphasis on those cases where semiconductivity is preserved when the (mobile) dopant concentration changes and ambipolar behavior can be obtained by dopant mobility. Dopant diffusion and drift are of interest not only in materials such as Si:Li, known from its use in radiation detectors, but also in other semiconductors, ranging from II-VIs and related compounds, such as (Hg,Cd)Te and CuInSe2 to III-Vs and potential high temperature semiconductors, such as diamond. Better understanding of the phenomena is important also because of the implications that it has for device miniaturization, as dopant diffusion and drift put chemical limits to device stability. Such understanding can also make dopant electromigration useful for low-temperature doping. Some basic theory for electric-field-induced dopant migration is given and compared to experiments.

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