[Paper] High efficiency n-Si/p-Cu2O core-shell nanowires photodiode prepared by atomic layer deposition of Cu2O on well-ordered Si nanowires array

Hangil Kim, Soo-Hyun Kim, Kyung Yong Ko, Hyungjun Kim, Jaehoon Kim, Jihun Oh, Han-Bo-Ram Lee

Electronic Materials Letters, May 2016, Volume 12, Issue 3, pp 404-410



DOI: 10.1007/s13391-016-5356-2



Abstract

A highly efficient n-Si/p-Cu2O core-shell (C-S) nanowire (NW) photodiode was fabricated using Cu2O grown by atomic layer deposition (ALD) on a well-ordered Si NW array. Ordered Si nanowires arrays were fabricated by nano-sphere lithography to pattern metal catalysts for the metal-assisted etching of silicon, resulting in a Si NW arrays with a good arrangement, smooth surface and small diameter distribution. The ALD-Cu2O thin films were grown using a new non-fluorinated Cu precursor, bis(1-dimethylamino-2-methyl-2-butoxy)copper (C14H32N2O2Cu), and water vapor (H2O) at 140°C. Transmission electron microscopy equipped with an energy dispersive spectrometer confirmed that p-Cu2O thin films had been coated over arrayed Si NWs with a diameter of 150 nm (aspect ratio of ∼7.6). The C-S NW photodiode exhibited more sensitive photodetection performance under ultraviolet illumination as well as an enhanced photocurrent density in the forward biasing region than the planar structure diode. The superior performance of C-S NWs photodiode was explained by the lower reflectance of light and the effective carrier separation and collection originating from the C-S NWs structure.