Electrical planarization of carbon nanotube thin films for electronic device applications
Various examples are provided related to electrical planarization of carbon nanotube thin films or networks. In one example, a method includes depositing one or more thin protective organic and/or inorganic layer across a nanotube film; disrupting electrical conductance of portions of the nanotube film by exposure of out-of-plane nanotubes to a planarization process that disrupts the electrical conductance through the one or more thin protective organic and/or inorganic layer; and removing the one or more thin protective organic and/or inorganic layer from the nanotube film.
1 . A method for electrical planarization of nanotube films or networks, comprising:
depositing one or more thin protective organic and/or inorganic layer across a nanotube film;
disrupting electrical conductance of portions of the nanotube film by exposure of out-of-plane nanotubes to a planarization process that disrupts the electrical conductance through the one or more thin protective organic and/or inorganic layer; and
removing the one or more thin protective organic and/or inorganic layer from the nanotube film.
2 . The method of claim 1 , wherein the nanotube film is disposed on a substrate surface, the nanotube film having an average nanotube film thickness, and the electrical conductance of out-of-plane nanotubes that protrude more than 10 times the average nanotube film thickness above the substrate surface is disrupted.
3 . The method of claim 1 , wherein the nanotube film comprises single wall carbon nanotubes.
4 . The method of claim 1 , wherein the nanotube film is disposed on a substrate in electrical contact with one or more contact pad or contact electrode.
5 . The method of claim 4 , wherein the substate is a glass substrate.
6 . The method of claim 4 , wherein at least one of the one or more contact pad or contact electrode is connected to a current supply line.
7 . The method of claim 1 , wherein at least a portion of the out-of-plane nanotubes is formed over a particle.
8 . The method of claim 1 , wherein the one or more thin protective organic and/or inorganic layer is deposited over the nanotube film.
9 . The method of claim 8 , wherein the one or more thin protective organic and/or inorganic layer comprises PMMA (polymethyl methacrylate).
10 . The method of claim 8 , wherein the one or more thin protective organic and/or inorganic layer has a thickness in a range from about 50 nm to about 300 nm.
11 . The method of claim 10 , wherein the one or more thin protective organic and/or inorganic layer has a thickness in a range from about 70 nm to about 200 nm.
12 . The method of claim 1 , wherein the planarization process comprises exposure of the out-of-plane nanotubes to oxidation through the one or more thin protective organic and/or inorganic layer.
13 . The method of claim 12 , where the out-of-plane nanotubes are exposed to an electrolyte for electrochemical oxidation.
14 . The method of claim 13 , wherein the electrolyte comprises a KOH electrolyte.
15 . The method of claim 12 , where the out-of-plane nanotubes are exposed to an oxygen plasma asher for oxidation.
16 . The method of claim 12 , where the out-of-plane nanotubes are exposed to ultraviolet (UV)/ozone for oxidation.
17 . The method of claim 12 where the out-of-plane nanotubes are exposed to chemicals that disrupt the nanotube conductance by esterification/amidation, halogenation, cycloaddition, radical, nucleophilic or electrophilic addition.
18 . The method of claim 1 , further comprising:
forming a layer of semiconducting channel material on top of the nanotube film; and
forming one or more electrodes on top of the layer of semiconducting channel material.
19 . The method of claim 18 , wherein the layer of semiconducting channel material comprises an organic semiconductor.
20 . The method of claim 18 , wherein the one or more electrodes comprises a drain electrode.
21 . The method of claim 18 , wherein OLED layers are deposited on top of the level of semiconducting channel material followed by deposition of an electron injecting drain electrode.
22 . The method of claim 1 , further comprising:
forming a layer of dielectric material on top of the nanotube film; and
forming one or more electrodes on top of the layer of dielectric material to provide a top gate electrode.
23 . The method of claim 1 , further comprising:
forming a layer of dielectric material on top of the nanotube film to isolate the nanotube film from subsequently deposited layers.