Installation C Task Force: D. Anglos
Installation C provides access to three excimer lasers with pulse energies up to 600mJ at
150Hz, resulting in focused intensities of 109-1010 W/cm2. They are used mainly for various
material processing studies, in certain cases complemented by two low-power CO2 lasers as
needed. The emphasis in Installation C is on the offering of workstations oriented to
specific application areas of technological interest. In that respect Installation C also
provides access to a wide range of material characterisation facilities for the evaluation
of the results.
Excimer laser material processing workstations
Thin Film Deposition stations
The main technique employed for the deposition of thin films, the Pulsed Laser Deposition (PLD),
is realized by experimental setups dedicated to the study of the principles involved and emphasis is
placed on capability for growth of specific coatings. The workstations are modular in nature and allow
for configurations to work on a variety of substrate geometries.
These capabilities are implemented in workstations equipped with rotating targets driven
by either vacuum-compatible stepper-motors or external DC motors, double target arrangement
for colliding plasmas deposition, large optical access for plume diagnostics, large area
deposition by means of combined translational/rotational target/substrate movement,
substrate heating by either tungsten wire or CO2 lasers. All stations are complemented by
computer controlled flow metering and flow sequencing systems, if required.
Time-of-flight mass spectroscopy an intensified gated CCD camera and a streak camera are
used to determine the plume characteristics. Profillometry, microhardness tester, scanning
electron microscopy, transmission electron microscopy and electron probe X-ray analysis are
employed for the ex-situ film characterization. An X-Ray Diffractometer provides more
information on the thin film microstructure.
Films of a variety of materials can be grown on any substrate such as metals, ceramics,
composites and fiber optics. Coatings of current interest include high-Tc superconductor
thin films, epitaxial oxides on semiconductors, diamond-like carbon films, refractory
materials, certain metals such as Pt, Ti, Au, ferroelectrics, polymers and biocompatible
The unit consists of a suitably modified UV microscope system and optics, in conjunction
with a KrF excimer laser. The high power laser beam is used for imaging an arbitrary master
mask on target. The target is placed on a system of high precision Burleigh x-y translation
stages powered by piezoelectric motors offering 50 nm position measurement accuracy with 4
nm minimum step. Photoablation based etching of patterns with arbitrary morphology is
possible via raster scanning. The system, which is enclosed in an environmentally stable
cubicle, is capable of etching patterns of high resolution of the order of one micron and
excellent etching quality.
Application Areas: Fabrication of microoptical components such as diffractive elements
including Bragg gratings, microlenses, microlens arrays, computer generated holograms;
additionally micromirrors, couplers, filters and distributed feedback lasers; Fabrication
of micromechanical components such as microsensors, micromotors etc.
Holography and Optical Processing workstation
The workstation consists of several cw lasers operating in the region from the UV to the
near IR (e.g. HeCd, HeNe, AlGaAs) which can be used for the recording of volume holograms
as well as holograms in waveguides. Depending on the material used, both static and dynamic
holographic recording is possible. Real-time optical processing of images is also possible
by exploiting the dynamic nature of holograms recorded in photorefractive materials such as
BaTiO3, KNbO3, Bi12SiO3. Characterization of holographic gratings and other optical
structures is available. Studies in optoelectronics and related devices can be undertaken.
Writing constant and variable pitch (chirped) Bragg gratings in fibers, wave-guides, as well
as holograms by using interferometric or holographic techniques. Interference patterns with
minimum pitch of a few laser wavelengths can be holographically produced, complementing the
Application Areas: Photorefractive optics in optical signal processing: phase
conjugation; image amplification; optical detection; static and dynamic holography,
including holographic recording and storage and optical interconnect systems. Fabrication
and testing of optical waveguides, waveguide sensors etc. Study of new non-linear optical
materials such as polymers, bacteriorhodopsin, fullerenes, chalcogenides etc. Development
of new optical systems for biomedical applications. Fibre-sensors; Fibre-lasers; Fibre
amplifiers; Gratings on conventional fibers; Fibre wavelength multiplexing.
Laser-Integrated Molecular Beam Epitaxy (LIMBE) station
A unique Molecular Beam Epitaxy (MBE) reactor which consists of two growth chambers with
integrated laser processing capability, sharing the same entry-lock and preparation/analysis
chambers, is installed in 40m2 of class 10.000 clean room space.
One growth chamber of the MBE reactor is for the epitaxy of III-V arsenide semiconductors
using solid material sources. It contains 8 thermal sources (K-cells) that include Ga, As,
Al and In for material structures, as well as Si and Be for n- and p-type doping. It is
equipped with a Reflected High Energy Electron Diffraction (RHEED) system for in-situ
monitoring of the epitaxial process and surface reconstructions, a Residual Gas Analyzer
(RGA), a flux monitoring ion-gauge and a rotating holder capable for wafer diameters up to
3 inches. An excimer laser is available for the irradiation of the substrate surfaces,
including a beam scan system, which in combination with substrate rotation allows for the
uniform exposure of a growing 3 inch wafer.
The second growth chamber is dedicated to solid source epitaxy of Si and solid or gas
source epitaxy of SiC. It is equipped with 2 electron-gun sources (one of Si and one for C),
a gas source of C2H2 and 3-K cells for doping. It also includes a rotating substrate holder
(up to 3 inches) , a RHEED system, a quartz oscillating thickness monitor and a movable
flux monitoring ion-gauge. A laser beam scanning system is under construction.
The preparation/analysis chamber includes a heating stage for substrate outgasing up to
600-700oC and an Auger Electron Spectroscopy (AES) system for surface chemical analysis,
which will be upgraded with capabilities for X-ray Electron Spectroscopy (XPS) in the near
Electrical and optical characterization of the epitaxial thin films is carried out by a
Biorad fully automated 300K and 77K Hall mobility measurement station, a Biorad PN4300
fully automated Semiconductor CV Profiler, a BIORAD DL4600 automated DLTS system, and a
Photoreflectance (300K)/Photoluminescence (12K) system.
Application Areas: Laser assisted MBE growth (GaAs, AlAs, AlGaAs, InGaAs, InAlAs, Si,
SiC); In situ annealing, alloying, recrystallization; Laser cleaning of semiconductor grade
wafers (GaAs, InP, Si, SiC, Al2O3, etc); Laser-induced etching of semiconductor layers with
ablation (GaAs, InGaAs, InAlAs, AlGaAs, Si, SiC);
X-ray Scattering, Diffraction, and Reflectivity station
The application of x-ray scattering and diffraction methods to the investigation of the
structure-morphology and phase transitions in self-assembled systems is an area of great
scientific and technological interest. A common characteristic of the structure of complex
systems is their organization in space over broad length scales ranging from A to mm and
only scattering techniques produce information on the morphology on various length scales.
At the same time, the investigation of the morphology and transitions in confined geometries
and/or near surfaces/interfaces requires the use of reflection techniques.
The x-ray workstation includes a high flux Rigaku D/max-2400 generator capable of
producing simultaneously two x-ray beams. The characteristics of the generator are:
rotating anode with changeable target material capability; horizontal tube with 2 Be
windows and electromagnetic shutters; Line and point focus; 12 kW maximum power output, 60
kV maximum voltage, and 200 mA maximum current; 0.5x10 mm2 focal spot size. Two instruments
are attached to the generator: a small-angle x-ray scattering camera (2j range: -3° to
+3°, slit collimation) with a position sensitive detector (100 mm effective length, 10
mm window height), and an x-ray diffractometer (2j range: -60° to +158°) which can
be substituted with an x-ray reflectometer with a thin film attachment. The x-ray
workstation can be combined with dynamic light scattering and rheo-optics.
Application Areas: Investigations of structure-morphology and phase transitions
in self-assembled system; Kinetics of phase transitions and interfacial partitioning.