Solvent-controlled spin-coating method for large-scale area deposition of two-dimensional silica nanosphere assembled layers.
In this article, we show that introducing a N,N-dimethyl-formamide (DMF) solvent for silica nanosphere (SNS) monolayer spin-coating can offer a low-cost and simple spin-coating approach for SNS monolayer deposition even on large-area silicon surfaces. From our method, more than 95% monolayer coverage for a 2 in round Si surface was achieved, which is one of the highest reported coverage by a spin-coating method. We prove that DMF offers highly enhanced wettability and slow solvent evaporation rate compared to a conventional solvent, water, in addition to excellent SNS dispersibility in solution preventing SNS cluster deposition on the surface and consequently produces a close-packed SNS monolayer with good uniformity over the surface. In addition, the benefits of DMF are retained as the deposition area increases indicating its high tolerance to spin-coating area. Better than 90% SNS monolayer coverage on a 4 in Si substrate was achieved with the DMF spin-coating method. Moreover, DMF has the advantage that SNS spin-coating can be done under common ambient laboratory conditions with 100% pure DMF unlike previous approaches which require humidity and temperature controls or additional surfactant additions to the solution.
School for Engineering of Matter, Transport and Energy, and ‡School of Electrical, Computer and Energy Engineering, Arizona State University , Tempe, Arizona 85287, United States.
Jea-Young
JY
Choi
T L
TL
Alford
Christiana B
CB
Honsberg
D004126:Dimethylformamide / Q000737:chemistry*; D054118:Nanospheres / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D014867:Water / Q000737:chemistry*; D017155:Wettability
D014867:Water; D012822:Silicon Dioxide; D004126:Dimethylformamide