Plasma Technology  

Si nanowire growth

Si nanowire growth
with 13 MHz plasma at 390° C
onto Au seed layer

ca 5 nm thick Au/Pd catalyst layer
Nanowires of varying diameter
grown thermally by catalytic
decomposition of silane (400°C)


Selective Si Nanowire Growth

Si nanowire growth by CVD

Si nanowire growth by CVD
1 µm high, 33 nm diameter
grown at 400°C

Possible to grow nanowires
selectively at catalyst sites
(in this case Au particles)
Plasma enables etching native
oxide in situ to encourage
epitaxial growth.




Si Nanowires grown on
molten Ga catalyst

Si Nanowires grown on
Au film catalyst

Si Nanowire Growth

 

High temperature ramp rate allows anneal
and different process steps to run at different
temperatures within a reasonable time frame.

Plasma enables the catalyst thin film to form
islands which would not form without at that
temperature.

Plasma provides higher activation of catalyst
leading to greater growth rate and denser
tubes due to more catalyst sites being active.

Plasma enables etching native oxide in situ
to encourage epitaxial growth.

Equipment:
Plasmalab System 100

Technology:
Parallel Plate Reactor
Shower Head Gas inlet
temperature range: 350° - 600° C

vertical growth rate up to 150 nm/ min

SNWs can be grown with or without plasma.
The plasma is also used to preclean the seed
layer and to clean the process chamber.


PECVD and CVD technology

 

Nanofab
(Plasmalab System 100)


Si nanowire growth by CVD

Si nanowire growth by CVD
25 nm diameter

 

Metal Catalysts are typically Au, Al
or Al (and Ga, In)


Deposition of silicon nanowires for application in
solar cells is a relatively new but exciting field of
research. Silicon nanowires show strong optical
absorption across a much broader wavelength range
than silicon wafers. They provide the potential to
reduce the cost of production compared to traditional
crystalline silicon cells and could achieve conversion
efficiency of up to 18% under 1 sun illumination.

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