Spontaneous hyper-branching in ZnO nanostructures: morphology dependent electron emission and light detection

Abstract

The structure and intrinsic defect-induced electron field emission and photodetection are monitored in ZnO nanoforms with assorted morphology prepared in ambient conditions via a facile wet chemical approach.

Morphology Dependent Conductivity and Photoconductivity of Ionic Porphyrin Crystalline Assemblies

“…The deeper trap states tend to recombine non-radiatively by emitting phonons. 4,13,65,66 Thus, when the laser light is first turned on, the defect states in the H 2 TAPP:H 4 TSPP sheaves are mostly unoccupied. Many of the electrons that are excited into the conduction band fall into the low energy defect states and become immobilized.…”

“…In particular, branched and hyperbranched 3D structures with their high aspect ratios were shown to have enhanced photoresponse compared to their 1D or 2D counterparts, where the three different topologies share the same organizational structure and chemical composition., 6,11,12,16,18 For example, ZnO hyperbranched nanostructure exhibited a photocurrent gain of 10 4 higher than that of a 1D nanorod when both samples were illuminated with a 350 nm laser light. 4 Similarly, the hierarchical branched form of CdTe displayed strong photoluminescence that was almost 10-fold more intense than that detected from 1D CdTe nanowires. 8 Studies that quantitatively compare optoelectronic properties of organic semiconductors with 3D morphologies and the photoresponse of their lower dimensionality topologies are not readily available.…”

“…[1][2][3] This morphology or topology is generally controlled during the growth process and is directed by the covalent or noncovalent interactions between the materials' atomic or molecular building blocks. The influence of different morphological forms of crystalline inorganic semiconductors (primarily metal oxides, [4][5][6][7] and chalcogenides [8][9][10] on their performance in photovoltaics, 4,6,8,11,12 sensing, 13,14 catalysis 15,16 and batteries 7,17 has been well documented. In particular, branched and hyperbranched 3D structures with their high aspect ratios were shown to have enhanced photoresponse compared to their 1D or 2D counterparts, where the three different topologies share the same organizational structure and chemical composition., 6,11,12,16,18 For example, ZnO hyperbranched nanostructure exhibited a photocurrent gain of 10 4 higher than that of a 1D nanorod when both samples were illuminated with a 350 nm laser light.…”

Fabrication of ZnO Nanobrushes by H2–C2H2 Plasma Etching for H2 Sensing Applications

“…The large surface area of the presented nanobrushes combined with the ease of fabrication as well as the versatility of ZnO as a material makes them ideal candidates for many applications beyond sensing. Possible applications include catalysis, energy generation, , field emission, and cathodoluminescence . The plasma treatment process in principle allows for large quantities of ZnO tetrapods being treated at the same time limited only by plasma chamber size.…”

“…Possible applications include catalysis, 68 energy generation, 10,31 field emission, 69 and cathodoluminescence. 70 The plasma treatment process in principle allows for large quantities of ZnO tetrapods being treated at the same time limited only by plasma chamber size. Together with the capability to produce sufficient amounts of ZnO tetrapod source material upscaling of the process can readily be achieved.…”