p-Type behaviour of electrodeposited ZnO:Cu films

Abstract

Cu-doped ZnO (ZnO:Cu) thin films and ZnO/ ZnO:Cu homojunction devices were electrodeposited on conductive glass substrates in a non-aqueous electrolyte containing Cu and Zn salts. The Cu content of the films is proportional to the Cu/Zn precursor ratio in the deposition electrolyte. ZnO:Cu was found to be of a hexagonal wurtzite structure with (002) preferred orientation. A transition from n-type to p-type was observed for ZnO:Cu films with a Cu/ Zn ratio higher than 2% as inferred from the change in the direction of the photocurrent. The rectifying characteristics shown by homojunction devices further confirm the p-type conductivity of ZnO:Cu layers.

Enhanced Solar Photoelectrochemical Conversion Efficiency of ZnO:Cu Electrodes for Water-Splitting Application

“…Reduction in the band gap thus facilitates excitation of an electron from the valence band to the conduction band, even under illumination of visible light photons. This is beneficial for achieving an improved PEC performance from a UVactive material [34][35][36][37][38]. This study confirms that the incorporation of an optimal concentration of Cu in ZnO can yield an efficient solar light absorbing optical system, which can be useful for the solar energy applications.…”

“…Expectedly, as there is negligible difference in the ionic radii of Cu and Zn, the doping shows no effect related to ZnO host lattice distortion. Similar results have been reported in the literature for Cu-doped ZnO films [33][34][35]. The crystallite size of all the films was estimated by using the Debye-Scherrer analysis [40].…”

“…Further, they reported the application of these films in NO 2 gas sensing. Similarly Mari et al [35] reported, p-type Cu-doped ZnO films obtained by electrodeposition method. Thus, it can be clearly understood that a variation in Cu-doping concentration renders either ntype or a p-type conductivity to host ZnO lattice.…”

Effects of Cu–Zn phases on electronic properties in ZnO:Cu films

“…Copper on a substitutional site has a lower formation energy compared to an interstitial site, which can weaken the self‐compensation effect, resulting in a stable p ‐type ZnO film. The p ‐type ZnO:Cu films have been prepared using the methods of magnetron sputtering, molecular beam epitaxy, hydrothermal, and electrodeposition . Kim et al shows the results that the conduction type of ZnO:Cu film is dependent on the oxygen gas pressure during deposition.…”

Effect of Na Doping on the Nanostructures and Electrical Properties of ZnO Nanorod Arrays

“…The n-type ZnO is available even without any intentional doping, but it is very difficult to dope ZnO p-type. Many groups have realized ptype ZnO conversion by doping group V elements (N [2], P [3], As [4], and Sb [5]) and groups I and IB (Li [6], Na [7][8][9], K [10], Ag [11], and Cu [12]), but the stability was not good. Among the group V elements, N is the most suitable dopant because it has about the same ionic radius as O and thus should readily be substituted on O sites.…”