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Source for the Deposition of Fullerene Thin Films

IP.com Disclosure Number: IPCOM000122348D
Original Publication Date: 1991-Nov-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 48K

Publishing Venue

IBM

Related People

Gambino, RJ: AUTHOR [+1]

Abstract

Disclosed is a source for depositing thin films on the molecular form of carbon known as fullerene starting with graphite as a source. A graphite target is positioned in a chamber which is evacuated and back filled with 100 Torr helium gas. The target is laser ablated with a pulsed laser beam which passes through a window in the wall of the chamber. The evaporation flux impinges on a heated surface which is held at 450~C. This surface acts as a secondary evaporation source because the lower molecular weight fullerenes C60 and C70 have a low sticking probability on a hot substrate. These materials sublime at about 450~C. A substrate held at a lower temperature, e.g., room temperature or below is positioned to intercept the flux of fullerene molecules evaporating from the heated surface.

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Source for the Deposition of Fullerene Thin Films

      Disclosed is a source for depositing thin films on the
molecular form of carbon known as fullerene starting with graphite as
a source.  A graphite target is positioned in a chamber which is
evacuated and back filled with 100 Torr helium gas.  The target is
laser ablated with a pulsed laser beam which passes through a window
in the wall of the chamber.  The evaporation flux impinges on a
heated surface which is held at 450~C.  This surface acts as a
secondary evaporation source because the lower molecular weight
fullerenes C60 and C70 have a low sticking probability on a hot
substrate.  These materials sublime at about 450~C.  A substrate held
at a lower temperature, e.g., room temperature or below is positioned
to intercept the flux of fullerene molecules evaporating from the
heated surface. With repeated pulsing of the laser, a thin film of
the low molecular weight fullerenes C60 and C70 is deposited on the
substrate.  The film consists mainly of C60 with about 10% C70 .

      It is possible to combine the primary and secondary source into
one structure.  The graphite source (a block of high purity graphite)
is drilled out to form a deep well. The block of graphite is held at
450~C in 100 Torr of helium.  The laser is focussed on the graphite
at the bottom of the well.  The high molecular weight evaporated
material condenses on the walls of the well but the C60 molecules do
not stick so they emerge...