Control of the Microstructure and Crystalline Orientation of ZnO Films on a Seed-free Glass Substrate by Using a Spin-Spray Method

Abstract

ZnO films on nonseeded substrates with controllable microstructures and crystal orientations were fabricated with a spin-spray method employing trisodium citrate as an additive. The microstructure of the films was made to change from a rod array to a dense film by increasing the trisodium citrate concentration in the solution. This change in structure was accompanied by a weakening of the 002 peak in the XRD pattern. After postdeposition heating, the ZnO rod arrays showed a decrease in visible luminescence, whereas dense ZnO films showed sharp UV luminescence and a weak broad visible luminescence, thus demonstrating a difference in the defect structure of the samples. We tuned the microstructures of ZnO films on nonseeded substrates by using the spin-spray method and analyzed the formation mechanism.

Pulverization of oxide powders utilizing thermal treatment in ammonia-based atmosphere

“…However, there are still some problems. For instance, powders precipitated in solutions often contain residual solvent molecules [9], and the precipitation of doped powders from single solutions is not always successful because the solubility of each element is different. Hence, a combination of calcination and milling is still the most frequently used method of powder synthesis.…”

Transparent ZnO Films Deposited by Aqueous Solution Process Under Various pH Conditions

“…ZnO film deposited by the spin-spray method generally has a rod array structure that can be tuned to form a transparent continuous film by the addition of citrate ions to the solution. 17 However, despite the addition of citrate ions, the ZnO film deposited at a mixed solution pH of 11.3 had a rough surface.…”

“…The presence of trisodium citrate is an important factor for the formation of a continuous structure because citrate ions are adsorbed onto the ZnO (001) planes and suppress film growth along the c-axis, which enables the formation of a dense and continuous structure. 17 The pH of the reaction solution was controlled by changing the amount of ammonia solution. ZnO films were deposited by spraying these solutions onto glass substrates fixed on a heated rotating disk (temperature = 95°C).…”

Fabrication of Al-Doped ZnO Film with High Conductivity Induced by Photocatalytic Activity

“…It is thought that the change in the surface morphology and preferential growth orientation might be affected by addition of citrate ions. 18 In our previous study, we reported the presence of carboxyl group, e.g., v as (COO À ) and v s (COO À ) signals, in ZnO film with addition of citrate, changing the crystal growth behavior of ZnO. Because added citrate ions were adsorbed to (001) plane, growth along c-axis is suppressed.…”

“…Because added citrate ions were adsorbed to (001) plane, growth along c-axis is suppressed. 18 As a result, as-grown ZnO with citrate ions exhibits polycrystalline structure with random orientation. These variations of crystal growth on addition of citrate ions also changed the surface morphology from rod to dense and continuous structure.…”