Transport, Analyte Detection, and Opto-Electronic Response of p-Type CuO Nanowires

Abstract

In this article, we introduce and provide details on a large-scale, cost-effective pathway to fabricating ultrahigh dense CuO nanowire arrays by thermal oxidation of Cu substrates in oxygen ambient. The CuO nanowires that are produced at ∼500 °C for ∼150 min feature an average length and diameter of ∼15 µm and ∼200 nm, respectively. The room temperature device-related characteristics such as transport, analyte detection and opto-electronic response of individual CuO nanowires have been probed by fabricating single CuO nanowire devices with the use of lift-off photolithographical techniques. The experiments confirm that as-grown nanowires are of p-type, have a band gap of ∼1.4 eV, and show strong sensitivity to both NO 2 and NH 3 gases. The devices also showed strong response to white light with device responsivity approaching ∼8 A/W for optical power densities of only ∼1 mW/cm 2 . Additionally, a complex interaction of photoproduced electron-hole pairs with the surface-originating chemisorbed agents including O 2 and NO 2 is found to drastically affect the gas sensitivity of CuO nanowire-based devices, where photoinduced adsorption of the analyte enhances the device response.

Copper (II) oxide nanowires for p-type conductometric NH3 sensing

“…Lower temperatures lead to high resistance values that made difficult the gas tests. The sensing mechanism of NH 3 by CuO was explored in the past [15,25]. To that end, the classic conduction model [26] of metal-oxides was adopted; surface oxygen species withdraw electrons from CuO decreasing the resistance due to the generation of holes in the material.…”

“…Among the different techniques to synthesize CuO nanowires, such as electro-spinning [17] and template-assisted growth [11], the direct oxidation of Cu foils [14][15][16] is easy to implement and scalable, providing pleasing results in terms of crystallinity and material quality [14]. These facts are triggering the research on one-dimensional (1D) CuO nanostructures [5,12,13,15,16], but the scope of their sensing characteristics remains uncompleted according to the authors' best knowledge since the studies performed with individual CuO nanowires have been limited up to now [12,13,15].…”

Building Selectivity for NO Sensing in a NOx Mixture with Sonochemically Prepared CuO Structures

“…Our interest in this study is on CuO, a p-type semiconducting material, which has been reported for detection of NO x [9][10][11][12][13][14], CO [12,[15][16][17], H 2 [18][19][20], and ethanol [14,[20][21][22][23][24][25]. CuO has also been studied as a NO x reduction catalyst in SCR [26,27].…”

Electronic structures ofCu2O,Cu4O3, and CuO: A joint experiment

“…Although CuO has received wide attention since the discovery of high temperature cuprate superconductors, its electronic structure has not been fully settled. The onset of direct-allowed absorption has been determined at 1.57 eV at low temperature [15], but the type of band gap (direct [28][29][30] or indirect [12,16,21,31]) remains controversial. The correlated nature of CuO presents a greater challenge for electronic structure calculations.…”