Structual and Optical Studies of Microstructures

We report atomic layer deposition (ALD) of ZnO thin films on O-polar surface crystalline Zinc Oxide (ZnO) substrates at the low temperature range of 120 to 200 degrees centigrade. The deposited films are studied with high resolution transmission electron microscopy (HRTEM), photoluminescence (PL) and surface photovoltage (SPV) spectroscopies. We find that the homoepitaxial films have a monocrystalline structure with a basal stacking fault density comparable with the substrate. The narrow excitonic linewidth of 2 meV at 8K and sharp SPV bandgap confirm the monocrystalline quality of the ZnO films. The deposition of material in three dimensional structures is important in a number of potential applications such as the creation of 3D photonic crystals, with potential uses in waveguides, LEDs, sensors, and optical switches. We report on the deposition of metal oxide films in high aspect ratio structures three dimensional with disordered structure. We report on the deposition of film up to 120 micrometers into the structure. Terahertz (THz) imaging and sensing technologies are increasingly being used for various security and medical purposes. The emergence of new THz applications has directly resulted in an increased interest regarding the biological effects associated with this frequency range. Knowledge of THz biological effects is desirable for the safe use of THz systems, identification of health hazards, and development of empirically-based safety standards. In this study, we developed a state-of-the-art exposure chamber that allowed for highly controlled and reproducible studies of THz biological effects.