TY  - JOUR
A1  - Crovetto, Andrea
A1  - Kojda, Danny
A1  - Yi, Feng
A1  - Heinselman, Karen N.
A1  - LaVan, David A.
A1  - Habicht, Klaus
A1  - Unold, Thomas
A1  - Zakutayev, Andriy
T1  - Crystallize It before It diffuses
BT  - kinetic stabilization of thin-film phosphorus-rich semiconductor CuP2
JF  - Journal of the american chemical society
N2  - Numerous phosphorus-rich metal phosphides containing both P-P bonds and metal-P bonds are known from the solid-state chemistry literature. A method to grow these materials in thin-film form would be desirable, as thin films are required in many applications and they are an ideal platform for high-throughput studies. In addition, the high density and smooth surfaces achievable in thin films are a significant advantage for characterization of transport and optical properties. Despite these benefits, there is hardly any published work on even the simplest binary phosphorus-rich phosphide films. Here, we demonstrate growth of single-phase CuP2 films by a two-step process involving reactive sputtering of amorphous CuP2+x and rapid annealing in an inert atmosphere. At the crystallization temperature, CuP2 is thermodynamically unstable with respect to Cu3P and P-4. However, CuP2 can be stabilized if the amorphous precursors are mixed on the atomic scale and are sufficiently close to the desired composition (neither too P poor nor too P rich). Fast formation of polycrystalline CuP2, combined with a short annealing time, makes it possible to bypass the diffusion processes responsible for decomposition. We find that thin-film CuP2 is a 1.5 eV band gap semiconductor with interesting properties, such as a high optical absorption coefficient (above 10(5) cm(-1)), low thermal conductivity (1.1 W/(K m)), and composition-insensitive electrical conductivity (around 1 S/cm). We anticipate that our processing route can be extended to other phosphorus-rich phosphides that are still awaiting thin-film synthesis and will lead to a more complete understanding of these materials and of their potential applications.
Y1  - 2022
U6  - https://doi.org/10.1021/jacs.2c04868
SN  - 0002-7863
SN  - 1520-5126
VL  - 144
IS  - 29
SP  - 13334
EP  - 13343
PB  - American Chemical Society
CY  - Washington
ER  -