Institute of Solid State Physics


SS20WS20SS21WS21SS22WS22SS23      Guidelines for Master Students

Synthesis of ZnO nanowires
Julia Fritzenwallner
Festkörperphysik
11:15 - 12:15 Wednesday 10 March 2021 

Semiconductor nanostructures are extensively studied for their interesting fundamental properties and widespread applications in the next generation of electric devices and sensors. Owing to the application of 1-D nanostructures it is desirable to investigate how to fabricate and characterize 1-D nanoforms. [1]. In the past few years, a lot of effort has been made to produce a wide variety of nanostructures such as wires, rods and tubes using different experimental approaches. [2]. Most methods are based on thermal oxidation, thermal evaporation, chemical vapour deposition (CVD) and plasma enhanced chemical vapor deposition (PECVD).

In this work thermal oxidation was used to produce ZnO (zinc oxide) nanowires (NW) directly on Zn foil in air. Compared with other catalyst assisted growth meachnisms, thermal oxidation is a catalyst free, simple and low-cost approach for producing ZnO nanowires. ZnO is an interesting material to investigate for electronics and optoelectronics uses due to its properties. It is a direct band gap semiconductor with a large excitation energy, is conductive and piezoelectric [2]. It is worthwhile to investigate the usability of ZnO NW as an application for mechanical gas sensors. We tried to find the best nanowire growth methode using available components, for a range of temperatures and reaction times. Furthermore, an Ar-flow or/and O-flow assisted experiments were performed. The nanowires have been characterized by SEM (Secondary Electron Microscopy), EDX (Energy dispersive X-ray) and XRD (X-ray diffraction).

It was found that the best growth conditions were pre-heating of the sample chamber with an Ar-flow of 1000 sccm at 600 °C for a reaction time of 1h. The approach with O-flow also showed nanowire formation but shorter and as many as the Ar set-up. It was not possible to control the O-flow very precisely because there was no flowmeter available.

Moreover, the EDX analysis showed that the average composition was 47 % Oxygen and 52 % Zn. In addition, the XRD analysis confirmed that the ZnO nanowires have hexagonal, crystalline structure.