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LOW-TEMPERATURE Si (111) HOMOEPITAXY AND DOPING MEDIATED BY A MONOLAYER OF Pb
 

Summary: LOW-TEMPERATURE Si (111) HOMOEPITAXY AND DOPING MEDIATED BY A
MONOLAYER OF Pb
O.D. DUBON, P.G. EVANS, J.F. CHERVINSKY, F. SPAEPEN, M.J. AZIZ, and J.A.
GOLOVCHENKO
Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138
spaepen@deas.harvard.edu
ABSTRACT
The codeposition of Pb during Si (111) molecular beam homoepitaxy leads to high-quality
crystalline films at temperatures for which films deposited on bare Si (111) are amorphous. Like
other growth mediating elements-- commonly called surfactants-- Pb segregates to the film
surface. Ion channeling and transmission electron microscopy reveal nearly defect-free epitaxy
for a Pb coverage of one monolayer and temperatures as low as 310 C. We have deposited films
up to 1000 in thickness with no indication that this is an upper limit for high-quality epitaxy.
However, a decrease in the Pb coverage during growth by only one tenth of a monolayer leads to
highly defective films at these temperatures. The codeposition of both As and Pb results in a
striking enhancement of the film quality as well. In this case, while the Pb again segregates to the
film surface, the As is incorporated into the film with no apparent segregation. Lead-mediated Si
epitaxy on As-terminated Si (111) produces high-quality films in which the As remains buried at
the substrate-film interface. These results show Pb-mediated Si (111) homoepitaxy to be a
promising strategy for the synthesis of layered structures having abrupt nanoscale dopant

  

Source: Aziz, Michael J.- School of Engineering and Applied Sciences, Harvard University
Evans, Paul G. - Department of Materials Science and Engineering, University of Wisconsin at Madison

 

Collections: Materials Science; Physics