Interface State Luminescence and Sub‐Bandgap Absorption Based on CuGaO₂ Nanoplates/ZnO Nanowires Heterostructure Arrays

Abstract

In this paper, the vertical arrays of ZnO nanowires (NWs) are uniformly grown on the surface of hexagonal CuGaO2 (CGO) nanoplates (NPs) through the hydrothermal method, forming the high‐density p–n heterojunction. The photoluminescence (PL) properties of these hetero‐assembled structures are characterized, and an obvious ultraviolet (UV) emission centered at 392.32 nm has been observed. Compared with the PL spectra of pure ZnO NWs, the UV peak red‐shift occurred and the spectrum broadened almost 2.5 times. A new emission located at 398 nm is attributed to the interface recombination which has been found through the Gaussian fitting. Furthermore, a red‐shift also appears in the absorption spectra of CGO NPs/ZnO NWs heterostructure, and the variation of light absorption properties results from the sub‐bandgap absorption effect in the p–n junction region. The light emission and absorption mechanisms occurring at the heterojunction have been investigated in terms of energy band theory. This work offers a new insight to realize micro/nano optoelectronic devices based on p‐CGO NPs/n‐ZnO NWs hetero‐assembled structures.

Localized Surface Plasmon Resonance Absorption Generated by Free Carriers in Zn‐Doped CuGa1−xZnxO2 Nanoplates

“…After the dense vertical ZnO NWs arrays grown on the CGO NP S , a red‐shift appears in the PL spectrum and the FWHM have been broadened obviously which compared with the pure ZnO NWs. According to our previous works, this phenomenon could be attributed to the interface recombination between the CGO NPs and ZnO NWs . As the heterojunctions structure synthesized, a built‐in electric field will be established through carrier diffusion, resulting in band bending at interface.…”

P-Type α-CuGaO2Electronics: A Study on Gap States and Fermi Level Pinning and a Solution to Schottky to Ohmic Transition for Electronic Applications

“…Assuming the complete ionization of the acceptors at room temperature, the hole concentration will also increase to this value. Shi and her team also reported a hole concentration of 10 14 cm –3 for CGO nanoplates synthesized by a hydrothermal method . On the other hand, Bredar et al synthesized CGO nanocrystals by the hydrothermal method and examined the production by XPS and electrochemical impedance spectroscopy.…”

“…CGO is also used as photoanode in the dye-sensitized solar cells (DSSCs) . In addition, the use of this substance as a hole transport layer (HTL) in perovskite solar cells has appeared very promising. , Due to the suitable electronic, optical, and chemical properties of CGO, it can also be used in p-channel transparent thin-film transistors (TTFTs), photocatalysts, p–n junctions, UV emitting diodes, H 2 generation, and photodetectors . However, the use of CGO in electronic and electro-optical devices requires the proper electronic connection between this semiconductor and a suitable metal, which always faces challenges.…”

Micro-Raman and X-ray Photoemission Spectroscopic Investigations of Heterojunction Between Delafossite CuGaO2 and Wurtzite ZnO Obtained by Hydrothermal Method

“…The Ga source materials were dissolved in nitrate or acetylacetonate sols, and the lms prepared with acetylacetonate had a higher transmittance than those prepared with nitrate. Xu et al [15] reported the formation of ZnO nanowires with n-type semiconductor properties on the surface of p-type delafossite, CuGaO 2 . The multihorned composites of hexagonal CuGaO 2 and ZnO nanowires were successfully fabricated by a hydrothermal method.…”