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Published July 1997 | public
Journal Article Open

Measurement of band offsets in Si/Si1–xGex and Si/Si1–x–yGexCy heterojunctions


Realization of group IV heterostructure devices requires the accurate measurement of the energy band offsets in Si/Si1–xGex and Si/Si1–x–yGexCy heterojunctions. Using admittance spectroscopy, we have measured valence-band offsets in Si/Si1–xGex heterostructures and conduction-band and valence-band offsets in Si/Si1–x–yGexCy heterostructures grown by solid-source molecular-beam epitaxy. Measured Si/Si1–xGex valence-band offsets were in excellent agreement with previously reported values. For Si/Si1–x–yGexCy our measurements yielded a conduction-band offset of 100 ± 11 meV for a n-type Si/Si0.82Ge0.169C0.011 heterojunction and valence-band offsets of 118 ± 12 meV for a p-type Si/Si0.79Ge0.206C0.004 heterojunction and 223 ± 20 meV for a p-type Si/Si0.595Ge0.394C0.011 heterojunction. Comparison of our measured band offsets with previously reported measurements of energy band gaps in Si1–x–yGexCy and Si1–yCy alloy layers indicates that the band alignment is type I for the compositions we have studied and that our measured band offsets are in quantitative agreement with these previously reported results.

Additional Information

©1997 American Vacuum Society. (Received 12 January 1997; accepted 3 April 1997) The authors would like to acknowledge support from DARPA MDA972-95-3-0047 for work at UCSD, HRL, and ASU, and from ONR Grant No. N00014-95-I-0996 for work at UCSD. E.T.Y. would like to acknowledge receipt of a Sloan Research Fellowship. Two of the authors, B.L.S. and E.T.Y., would also like to thank S.S. Lau for part of the equipment used in this work.


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