Fabrication of 3D structures of ZnO nanorods for gas sensing at room temperature

The purpose of this work is fabrication of 3D structures consist of Zinc Oxide (ZnO) nanorods. These devices would be employed for gas sensing at room temperature due to the potential increase in active surface area. There were results from research which have revealed that surfaces, covered by ZnO semiconductor, present sensing behavior. Also, there have been work in construction of 3D arrays of ZnO nanorods in the past but only its photocatalytic performance was investigated. That is why 3D scaffolds were fabricated in order to serving us substrates for growth of ZnO nanorods and examine the sensing behavior of ZnO on complex geometries. The aim is to increase of sensing behavior this semiconductor exhibits by increasing the surface area through which the semiconductor interacts with the environment. For the accomplishment of this work three main methods have been adopted. Firstly, the 3D scaffolds were constructed using Multiphoton Lithography (MPL) technique and the next step was deposition of seed Zn layer utilizing Pulsed Laser Deposition (PLD) technique. Finally, hydrothermal growth of ZnO nanorods was achieved by Aqueous Chemical Growth (ACG) technique. MPL is a direct laser writing technique for fabrication of 3D scaffolds with features on submicron scale with great accuracy. The idea is that phase transition from gel state to solid state can be occurred via multiphoton polymerization of photosensitive materials. After a special treatment, only the light exposed material can be remained with the final result the desire 3D structures. PLD is a physical vapor deposition procedure for thin films growth. It is a light-induced process in which stoichiometric transfer is achieved through vaporization of a material. Only requirements are a bulk target material, a substrate, a pulsed laser source and vacuum conditions and a pure layer of desired material can be deposited into a substrate. The role of seed Zn layer from PLD is crucial for uniformly growth of nanorods on substrates. ACG is a solution growth technique, which is a quite simple method for growth of nanostructures. It is taken place at relatively low temperatures, presenting several advantages such as the use of non-expensive equipment, the requirement of cheap and non-toxic reagents and the presence of non-hazardous by-products.The purpose of this work is fabrication of 3D structures consist of Zinc Oxide (ZnO) nanorods. These devices would be employed for gas sensing at room temperature due to the potential increase in active surface area. There were results from research which have revealed that surfaces, covered by ZnO semiconductor, present sensing behavior. Also, there have been work in construction of 3D arrays of ZnO nanorods in the past but only its photocatalytic performance was investigated. That is why 3D scaffolds were fabricated in order to serving us substrates for growth of ZnO nanorods and examine the sensing behavior of ZnO on complex geometries. The aim is to increase of sensing behavior this semiconductor exhibits by increasing the surface area through which the semiconductor interacts with the environment. For the accomplishment of this work three main methods have been adopted. Firstly, the 3D scaffolds were constructed using Multiphoton Lithography (MPL) technique and the next step was deposition of seed Zn layer utilizing Pulsed Laser Deposition (PLD) technique. Finally, hydrothermal growth of ZnO nanorods was achieved by Aqueous Chemical Growth (ACG) technique. MPL is a direct laser writing technique for fabrication of 3D scaffolds with features on submicron scale with great accuracy. The idea is that phase transition from gel state to solid state can be occurred via multiphoton polymerization of photosensitive materials. After a special treatment, only the light exposed material can be remained with the final result the desire 3D structures. PLD is a physical vapor deposition procedure for thin films growth. It is a light-induced process in which stoichiometric transfer is achieved through vaporization of a material. Only requirements are a bulk target material, a substrate, a pulsed laser source and vacuum conditions and a pure layer of desired material can be deposited into a substrate. The role of seed Zn layer from PLD is crucial for uniformly growth of nanorods on substrates. ACG is a solution growth technique, which is a quite simple method for growth of nanostructures. It is taken place at relatively low temperatures, presenting several advantages such as the use of non-expensive equipment, the requirement of cheap and non-toxic reagents and the presence of non-hazardous by-products