Individually addressable hybrid dimensional nanoarchitecture device arrays

Abstract

One-dimensional (1D) semiconductor nanomaterial arrays grown on two-dimensional (2D) layered nanomaterials can provide an excellent platform for realizing novel electronic and optoelectronic devices by synergistically combining the unique physical properties of 1D and 2D nanomaterials. 1D semiconductor nanomaterials work as efficient channels for carrier transport, thereby greatly improving the device performances of electronic and optoelectronic devices. Moreover, graphene layers, which have excellent electrical and thermal conductivities, and high mechanical strength and elasticity, are novel substrates that offer new functionalities such as transferability and flexibility. This dissertation presents the fabrication and characteristics of individually addressable nanorod device arrays based on 1D+2D hybrid dimensional nanomaterials. Ultrathin, flexible, and individually addressable ZnO nanorod device arrays on graphene layers were demonstrated. Using this system, we investigated the individual electrical characteristics of single ZnO nanorod within the arrays. Additionally, based on the optoelectronic and piezoelectronic characteristics of ZnO nanorods, we investigated photodetector and pressure sensor characteristics of the nanorod device arrays. Moreover, light-emitting diode (LED) arrays were fabricated using GaN/ZnO coaxial nanorod heterostructure arrays and their device characteristics were investigated. Metal-cored nitride microtube structures are discussed as a method to significantly improve nanostructured LED performance by improving the current-spreading characteristics. In addition to 1D+2D hybrid dimensional nanomaterial-based devices, semiconductor microstructure arrays grown on graphene substrates were used to show their potential for microdisplay. GaN microdisk LED arrays grown on graphene dots were assembled in ultrathin and individually addressable crossbar array for flexible, high-resolution microdisplay. Furthermore, for full-color microdisplay, morphology-controlled GaN microdonut-shaped and micropyramidal LEDs were used to demonstrate variable-color light-emitters. The interesting electrical and electroluminescence characteristics of the GaN nanoarchitecture LEDs are presented. The origin of multicolor emission is also investigated by analysing the structure and chemical composition of the LEDs by TEM. The catalyst-free molecular beam epitaxy (MBE) growth of InxGa1−xAs/InAs coaxial nanorod heterostructures on graphene layers are also demonstrated. Transmission electron microscopy (TEM) was used to investigate the crystallinity of the arsenide nanorods grown on graphene layers. Additionally, RHEED was used to investigate the growth behavior of nanorods on graphene layers in real time. Finally, monolithic integration of wide and narrow band gap semiconductor nanorods vertically on each surface of graphene are demonstrated by showing InAs nanorods/graphene layers/ZnO nanorods double heterostructures. Their structural characteristics are investigated by both the cross-sectional and plan view TEM. Moreover, their dual-wavelength photodetector characteristics are demonstrated.