nn6b04194_si_001.pdf (840.43 kB)
Ultrathin and Flat Layer Black Phosphorus Fabricated by Reactive Oxygen and Water Rinse
journal contribution
posted on 2016-09-01, 00:00 authored by Hyuksang Kwon, Sung Won Seo, Tae Gun Kim, Eun Seong Lee, Phung Thi Lanh, Sena Yang, Sunmin Ryu, Jeong Won KimUltrathin
black phosphorus (BP) is one of the promising two-dimensional
(2D) materials for future optoelectronic devices. Its chemical instability
in ambient conditions and lack of a bottom-up approach for its synthesis
necessitate efficient etching methods that generate BP films of designed
thickness with stable and high-quality surfaces. Herein, reporting
a photochemical etching method, we demonstrate a controlled layer-by-layer
thinning of thick BP films down to a few layers or a single layer
and confirm their Raman and photoluminescence characteristics. Ozone
molecules generated by O2 photolysis oxidize BP, forming
P2O5-like oxides. When the resulting phosphorus
oxides are removed by water, the surface of BP with preset thickness
is highly flat and self-protective by surface oxygen functional groups.
This method provides a fabrication strategy of BP and possibly other
2D semiconductors with band gaps tuned by their thickness.