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Photovoltaics Research Laboratories
This is the largest and most sophisticated bulk silicon solar cell
research facility in Australia, incorporating both the High Efficiency
and Buried Contact Cell Laboratories. Laboratory space of over 5500
m2 is located in the Electrical Engineering Building
and is serviced with filtered and conditioned air, appropriate cooling
water, processing gas, de-ionized water supply, chemical fume cupboards
and exhausts. There is an additional 460 m2 area immediately
adjacent to the laboratories for the accommodation of staff, research
students and laboratory support facilities. Off site, areas totalling
200 m2 are used for the storage of chemicals and equipment
spare parts.
The laboratories are furnished with a range of processing and characterisation
equipment including 37 diffusion furnaces, 6 vacuum evaporation
deposition systems, 2 laser-scribing machines, rapid thermal annealer,
four-point sheet-resistivity probe, quartz tube washer, silver,
nickel and copper plating units, infrared and visible wavelength
microscopes, 3 wafer mask aligners, spin-on diffusion system, automated
photoresist dual-track coater, photoresist spinner, electron beam
deposition system, TiO2 spray deposition, belt furnace
and a laboratory system control and data acquisition monitoring
system.
CNC Laser Scribe Tool
Recently, a new CNC laser-scribe tool has been installed, providing
a major upgrade to the laser machining capabilities of the Centre.
The laser scribe tool, shown above, has a 20 watt Nd:YAG laser for
infrared operation (1064 nm) and an optional frequency doubler for
green operation (532 nm). The work stage is CNC controlled allowing
1 micron positional accuracy and table speeds approaching 25 cm/second
across an area of 15 cm by 15 cm. The tool is used primarily for
Buried
Contact solar cell fabrication, cutting 35-micron wide laser
grooves as deep as 100 microns into silicon wafers. It can also
be used to cut other suitable materials, such as stainless steel.
Device Characterisation Laboratory
The Device Characterization Laboratory houses characterisation
equipment including “Dark Star”, the Centre’s
station for temperature controlled dark current-voltage measurements,
the Centre’s Fourier-transform infrared spectroscopy system,
admittance spectroscopy system, microwave carrier lifetime system,
ellipsometer, photoconductance decay equipment, infrared microscope
and equipment for spectral response and related optical measurements.
Optoelectronic Research Area
This facility was established in 2002 with several visible and
near-infrared semiconductor diode lasers and optical and electrical
instrumentation. This was enhanced with a second optical bench and
several further pieces of equipment in 2003. The facility is used
for photoluminescence and electroluminescence measurements in the
visible and infrared spectral range up to wavelengths of 2500nm;
photoluminescence excitation spectroscopy; luminescence experiments
with simultaneous two-colour illumination and Sinton lifetime testing
with the conventional flash-light replaced by a high-power light
emitting diode array. An area separate from the Device Characterisation
Area was necessary in order to meet stringent standards for avoidance
of laser eye and skin exposure for users and others. It shares cryogenic
cooling equipment with the Device Characterisation Area.
Optical characterisation bench.
Thin-Film Cell Laboratory
This 40 m2 laboratory is equipped with a range of equipment
for thin-film deposition and patterning, including a plasma-enhanced
chemical-vapour-deposition system, sputtering system, reactive-ion
etcher and vacuum evaporator. Also used by the Laboratory is an
Ion Assisted Deposition System physically located within the Photovoltaics
Research Laboratory. Other equipment of use in thin-film projects
is located within the Semiconductor Nanofabrication Facility.
In 2003, the Centre acquired a new remote microwave/RF plasma process
chamber for the deposition of thin dielectric films such as silicon
nitride, silicon dioxide and amorphous silicon. The system, shown
below, has a 40 x 20 cm2 process platen and can handle
large-area silicon wafers as well as smaller pieces. The dual-cylinder,
remote microwave supply can produce excellent-quality silicon-nitride
and silicon-dioxide films with precise control over the stoichiometry
at temperatures up to 500°C. Amorphous and microcrystalline
silicon films can also be deposited in the system.
Remote plasma PECVD machine
Semiconductor Nanofabrication Facility
The Centre also owns equipment within, and has access to, the Semiconductor
Nanofabrication Facility (SNF) at the University. This is a joint
facility shared by the Faculties of Science and Engineering and
houses a microelectronics laboratory and a nanofabrication laboratory
for e beam lithography. The SNF provides an Australian capability
for the fabrication of advanced nanoscale semiconductor devices
and their integration with microelectronics. SNF research projects
form an integrated effort to fabricate innovative semiconductor
nanostructures using the latest techniques of electron beam patterning
and scanning probe manipulation. A major applied objective of the
facility is the development of a prototype silicon nuclear spin
quantum computer.
Industry Collaborative Laboratory
This 300m2 laboratory houses equipment needed for many
of the industry-collaborative research activities in the Buried-Contact
Solar Cell group. The laboratory was refurbished in 1999 and several
new pieces of infrastructure have been acquired or constructed since,
including: a belt furnace; a state of the art laser micromachining
tool; a new PECVD deposition system (located in the adjacent thin
film solar cell laboratory); and a TiO2 spray deposition
station. The Buried-Contact Group is presently planning the acquisition
of a state-of-the-art thick film screen-printing tool.
Cleanroom facility in Bay Street, Botany
During 2003 the Centre has added a 120-m2 cleanroom
facility in Bay Street, Botany to its infrastructure, greatly improving
its experimental capabilities in the area of thin-films. This cleanroom
is equipped with several fume cupboards, two tube furnaces, an electron-beam
vacuum evaporator, a thermal vacuum evaporator, a glass washing
machine, a rapid thermal processing (RTP) machine, and a 5 chamber
cluster tool. The cluster tool presently features four plasma-enhanced
chemical vapour deposition (PECVD) chambers and one sputtering chamber.
The PECVD chambers enable the low-temperature deposition of dielectric
films (silicon oxide, silicon nitride, etc) and amorphous silicon
films (either n- or p-doped or undoped). Furthermore, samples can
be hydrogenated by PECVD using a hydrogen plasma at substrate temperatures
of up to 500 °C. The cluster tool’s sputtering chamber
is presently equipped with a ZnO target, enabling the deposition
of a transparent conductive oxide (TCO).
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