Transcript Research Interests

Research Interests
generally: application of physical
crystallography to materials science
and engineering problems of current
and future semiconductor technologies
recently: unintentional plastic
deformation of GaAs wafers and ingots
Peter Moeck
Dr. rer. nat.
currently: self assembled epitaxial
semiconductor quantum dots
R.W. Chan: “one cannot
easily get degrees in
… crystallography” ,
The Coming of Materials
Science, Pergamon, 2001
Somehow, I managed
to get two of them !
complementary: goniometry of direct
and reciprocal lattice vectors in TEM
(methodical and software development)
recently: unintentional plastic deformation of GaAs
wafers and ingots
Scanning infrared
polariscopy quantifies
shear strains
all experiments combined → new model
 technical modifications of equipment
Visible light interferometry
measures surface steps
10
resolved thermal shear stress [MPa]
X-ray topography at a
synchrotron reveals
dislocation structure
 unintentional plastic deformation gone
for good P. Möck, J. Appl. Cryst. 34 (2001) 65; Cryst. Res. Technol.
35 (2000) 529, J. Cryst. Growth 224 (2001) 11
5
stress for dislocation pairs
dislocation generation threshold, 5.46 MPa
stress for slip systems no. 1 and 2
stress for slip systems no. 5 and 6
0
0
90
180
270
angular coordinate [deg.], counting from [100]
Funding: Engineering and Physical Science Research Council, U.K.
360
currently: self assembled epitaxial semiconductor
quantum dots
P. Möck et al.,
IEE-Proc.
Optoelectron.
147 (2000) 209
AFM for individual
shapes and sizes
Triple crystal X-ray diffraction
for shapes and sizes over cm-2
Photoluminescence spectroscopy to
prove quantum dot activity
TEM and STEM revealed atomic
ordering within the quantum dots
for first time world wide! P. Möck et al.
J. Appl. Phys. 79 (2001) 946  opportunity
to create novel phases!! world wide
patent pending
Funding: Research Innovation Award, Campus Research Board of U of Illinois at Chicago
unsolved problem: how to identify the crystallographic phases?
Solution → complementary methodical developments, next slide
complementary: goniometry of direct and reciprocal
lattice vectors in TEM (methodical and software development)
Basic Ideas: determine crystallographic orientation of crystal with respect to
microscope coordinate system, i.e. determine a set of transformation matrices,
make crystallographic analyses, e.g. phase identification, orientation relationships,
grain boundary parameters, by manipulating these matrices, … works without
recourse to recorded high resolution phase contrast images or
diffraction patterns, can be done right at the microscope (but needs a good
specimen stage and compucentricity)
Plans: implement at software level at PSU’s FEI Tecnai G2 F-20 TEM/STEM,
employ for identification of crystallographic phase of non-cubic semiconductor
quantum dots and other nanocrystals, (i.e. solve problem last slide), develop further
in years to come for all kinds of crystallographic analyses
Collaborators on this project: Prof. P. Fraundorf, U. of Missouri at St. Louis, Dr. W.
Qin, Digital DNS Lab Meza, Motorola, W. Qin & P. Fraundorf, Ultramicroscopy 94 (2003) 245
German patents: DE 4037346 A1 and DD 301839 A7, 11/21/1989, description and
references at http://www.physics.pdx.edu/~pmoeck/goniometry.htm