https://doi.org/10.1051/epjap:200373
Defect imaging in ultra-thin SiGe (100) strain relaxed buffers
Universität Stuttgart, Institut fuer Halbleitertechnik
Pfaffenwaldring 47, D-70569 Stuttgart, Germany
Corresponding author: werner@iht.uni-stuttgart.de
Received:
3
July
2003
Accepted:
2
October
2003
Published online: 9 February 2011
Preferential etching is a simple and fast technique to evaluate the structural
perfection of a single-crystalline material. In the area of defects, the
etching rate of preferential etchants are different, so either hillocks or
pits (etch-pits) appear. But most of the etching solutions reveal the defects
only in thick layers or bulk materials, and often they are very specific for
each material. Hence an appropriate etchant based on the Schimmel solution was
developed by us for thin layer investigation. This modified Schimmel solution
contains 55 Vol% CrO3 (0.4 M) and 45 Vol% HF (49%). The etch rate of
this solution depends on the Ge content and on the degree of relaxation R.
For the investigated thin Si
Gex-heterolayers
(x = 0.3–0.5) this solution provides an excellent controllable etch rate
(0.12–0.48 µm/min), and shows a good capability of etch pit revealing,
so the elucidation of countable etch-pits occurs. We implemented also a method
for defect revealing based on the electrochemical capacitance voltage system.
The determination of the etch pit density is performed by optical microscopy
images (inverted dark-field and differential interference contrast) and by
atomic force microscopy.
PACS: 61.72.Ff – Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc. / 61.72.Lk – Linear defects: dislocations, disclinations
© EDP Sciences, 2004
