Open AccessNanocrystal Film Patterning by Inhibiting Cation Exchange via Electron-Beam or X-ray Lithography
Author(s) -
Karol Miszta,
F. Greullet,
Sergio Marras,
Mirko Prato,
Andréa Toma,
Milena P. Arciniegas,
Liberato Manna,
Roman Krahne
Publication year - 2014
Publication title -
nano letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.853
H-Index - 488
eISSN - 1530-6992
pISSN - 1530-6984
DOI - 10.1021/nl500349j
Subject(s) - nanocrystal , electron beam lithography , x ray photoelectron spectroscopy , lithography , materials science , nanotechnology , substrate (aquarium) , chemistry , optoelectronics , resist , chemical engineering , oceanography , layer (electronics) , geology , engineering
In this Letter we report patterning of colloidal nanocrystal films that combines direct e-beam (electron beam) writing with cation exchange. The e-beam irradiation causes cross-linking of the ligand molecules present at the nanocrystal surface, and the cross-linked molecules act as a mask for further processing. Consequently, in the following step of cation exchange, which is performed by directly dipping the substrate in a solution containing the new cations, the regions that have not been exposed to the electron beam are chemically transformed, while the exposed ones remain unchanged. This selective protection allows the design of patterns that are formed by chemically different nanocrystals, yet in a homogeneous nanocrystal film. Spatially resolved compositional analysis by energy-dispersive X-ray spectroscopy (EDS) corroborates that the selective exchange occurs only in the nonirradiated regions. We demonstrate the utility of this lithography approach by fabricating conductive wires and luminescent patterns in CdSe/CdS nanocrystal films by converting nonirradiated regions to Cu2-xSe/Cu2-xS. Furthermore, we show that X-ray irradiation too can lead to protection from cation exchange.