Deutsch Intern
Experimental Physics III

Molecular Beam Epitaxy

Our team works on the fabrication of ultrathin layer systems on the basis of III-V and II-VI semiconductors.

Introduction

The Molecular Beam Epitaxy (MBE) is a state-of-the-art procedure to fabricate high-quality semiconductor heterostructures. With this technique it is possible to dissect sharp interfaces between the layers and to accomplish comparatively easy an exact alloy composition or doping.

Description

Within the MBE reactor ultrahigh vacuum (UHV) conditions are realized. The source materials are evaporated using the elementary forms or compounds in specially designed effusion cells. The sources are generally of ultrahigh purity. The evaporated material is deposited on a suitable substrate with the mean free pass of the atoms in the molecular beam in the UHV being larger than the distance between the fusion cell and the substrates. Hence, interaction takes place only with the substrate surface on which the atoms are deposited.

The base pressure of the MBE reactor is in the range of a few 10-11 Torr to minimize the incorporation of impurities during the epitaxy process. In order to ensure a homogenous crystal growth the substrate is typically rotating and heated during the deposition process. The position rates are typically of the order 1 to 2 Angstroem per second.

Sketch of a MBE setup

Further reading

  • G. J. Davies, D. Williams, III-V MBE Growth Systems, in E. H. C. Parker (Ed.), The Technology and Physics of Molecular Beam Epitaxy, Plenum Press, New York 1985
  • M. A. Hermann, H. Sitter, Moelcular Beam Epitaxy, Springer Verlag, Berlin 1989
  • H. Ibach, H. Lüth, Festkörperphysik, Springer Verlag, Berlin 1988
  • B. A. Joyce, Reports on Progress in Physics 48, p. 1637 (1985)
  • E. Kaldis, Current Topics in Material Science (Vol. 9), North Holland, Amsterdam 1982
  • R. Kern, D. Aquilano, Fundamental Aspects of Epitaxy, in A. Baldereschi, C. Paorici (Eds.), Epitaxial Electronic Materials A, World Scientific, Singapur 1988