Abstract
Recently, copper oxide (CuO) has drawn much attention as a promising material in visible light photodetection with its advantages in ease of nanofabrication. CuO allows a variety of nanostructures to be explored to enhance the optoelectrical performance such as photogenerated carriers scattering and bandgap engineering. However, previous researches neglect in-depth analysis of CuO’s light interaction effects, restrictively using random orientation such as randomly arranged nanowires, single nanowires, and dispersed nanoparticles. Here, we demonstrate an ultra-high performance CuO visible light photodetector utilizing perfectly-aligned nanowire array structures. CuO nanowires with 300 nm-width critical dimension suppressed carrier transport in the dark state and enhanced the conversion of photons to carriers; additionally, the aligned arrangement of the nanowires with designed geometry improved the light absorption by means of the constructive interference effect. The proposed nanostructures provide advantages in terms of dark current, photocurrent, and response time, showing unprecedentedly high (state-of-the-art) optoelectronic performance, including high values of sensitivity (S = 172.21%), photo-responsivity (R = 16.03 A/W, λ = 535 nm), photo-detectivity (D* = 7.78 × 1011 Jones), rise/decay time (τr/τd = 0.31 s/1.21 s).
Highlights
Improve the performance of CuO with conventional nanomaterial approaches have been limited; previous works have utilized CuO nanomaterials made by synthesis and dispersion, resulting in randomly dispersed CuO nanomaterials[19,20,29]
The proposed nanostructure can be ideal for maximizing and minimizing photocurrent (Iph) and Idark, respectively, because a perfectly-aligned NW array causes a dramatic reduction in electrical resistivity, and enhances light absorption based on constructive interference by scattered light
(3) Higher responsivity (R = Iph/(Pin · A); Pin and A are power of incident light and light receiving area, respectively) and higher detectivity with higher Iph: because the CuO NWs are perfectly aligned with a certain pitch, the NWs do not form unnecessary networks with each other, resulting in an ideal light receiving field without any shaded areas
Summary
Improve the performance of CuO with conventional nanomaterial approaches have been limited; previous works have utilized CuO nanomaterials made by synthesis and dispersion, resulting in randomly dispersed CuO nanomaterials[19,20,29] These random CuO nanomaterials make irregular and undesignable networks, creating an additional current pathway and increasing Idark. These conventional nanomaterial methods limit the geometric design of nanomaterials, which is important for achieving additional performance enhancements in optical and photonic applications based on surface r esonance[33,34,35,36]. To demonstrate the performance-enhanced CuO photodetector, we proposed a 3-D nanostructure that consists of a perfectly-aligned, dense CuO NW array on a silicon dioxide (SiO2) nanograting substrate. By using the formulated fabrication method, we successfully demonstrated tens of devices in an array on a cm-scale substrate, all of which showed high uniformity and stable optoelectronic characteristics
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