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Applications of active control of light matter interactions within integrated photonics, hyper-spectral imaging, reconfigurable lasers, and selective bio-surfaces have enormously increased the demand for realization of optical modulation covering the spectrum from ultraviolet (UV) up to infrared (IR) wavelength range. In this study, we demonstrate ZnO-based actively tunable perfect absorber operating within UV and visible spectrum with more than 5 nm shift in the resonant absorption wavelength. Using spectroscopic ellipsometry technique, we extract temperature-dependent optical constants of atomic layer-deposited ZnO within 0.3-1.6 and 4-40 μm spectra. We also observe bandgap narrowing of ZnO at elevated temperatures due to lattice relaxation verified by the red-shift of phonon-modes. At around its bandgap, refractive index variations up to 0.2 is obtained and ZnO is shown to exhibit thermo-optic coefficient as high as 9.17 × 10-4 K-1 around the bandgap which is the largest among well-known large bandgap materials. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Here peptide amphiphile (PA) nanofiber network is exploited as a three-dimensional soft template to construct anatase TiO2 and wurtzite ZnO nanonetworks. Atomic layer deposition (ALD) technique is used to coat the organic nanonetwork template with TiO2 and ZnO. ALD method enables uniform and conformal coatings with precisely controlled TiO2 and ZnO thickness. The resulting semiconducting metal oxide nanonetworks are utilized as anodic materials in dye-sensitized solar cells. Effect of metal oxide layer thickness on device performance is studied. The devices based on thin TiO2 coatings (< 10 nm) demonstrate considerable dependence on material thickness, whereas thicker (> 17 nm) ZnO-based devices do not show an explicit correlation. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

A memory structure containing ultra-small 2-nm laser-synthesized silicon nanoparticles is demonstrated. The Si-nanoparticles are embedded between an atomic layer deposited high-κ dielectric Al2O3 layer and a sputtered SiO2 layer. A memory effect due to charging of the Si nanoparticles is observed using high frequency C-V measurements. The shift of the threshold voltage obtained from the hysteresis measurements is around 3.3V at 10/-10V gate voltage sweeping. The analysis of the energy band diagram of the memory structure and the negative shift of the programmed C-V curve indicate that holes are tunneling from p-type Si via Fowler-Nordheim tunneling and are being trapped in the Si nanoparticles. In addition, the structures show good endurance characteristic (>105program/erase cycles) and long retention time (>10 years), which make them promising for applications in non-volatile memory devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cataloged from PDF version of article. ZnO is an attractive material for both electrical and optical applications due to its wide bandgap of 3.37eV and tunable electrical properties. Here, we investigate the application potential of atomic-layer-deposited ZnO in uncooled microbolometers. The temperature coefficient of resistance is observed to be as high as -10.4%K-1 near room temperature with the ZnO thin film grown at 120 degrees C. Spectral noise characteristics of thin films grown at various temperatures are also investigated and show that the 120 degrees C grown ZnO has a corner frequency of 2kHz. With its high TCR value and low electrical noise, atomic-layer-deposited (ALD) ZnO at 120 degrees C is shown to possess a great potential to be used as the active layer of uncooled microbolometers. The optical properties of the ALD-grown ZnO films in the infrared region are demonstrated to be tunable with growth temperature from near transparent to a strong absorber. We also show that ALD-grown ZnO can outperform commercially standard absorber materials and appears promising as a new structural material for microbolometer-based applications.

Date of Conference: 17-20 June 2012

Herein, we report on atomic layer deposition of ternary InxGa1-xN alloys with different indium contents using a remotely integrated hollow cathode plasma source. Depositions were carried out at 200 degrees C using organometallic Ga and In precursors along with N-2/H-2 and N-2 plasma, respectively. The effect of In content on structural, optical, and morphological properties of InxGa1-xN thin films was investigated. Grazing incidence X-ray diffraction showed that all InxGa1-xN thin films were polycrystalline with a hexagonal wurtzite structure. X-ray photoelectron spectroscopy depicted the peaks of In, Ga, and N in bulk of the film and revealed the presence of relatively low impurity contents. In contents of different InxGa1-xN thin films were determined by energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Transmission electron microscopy also confirmed the polycrystalline structure of InxGa1-xN thin films, and elemental mapping further revealed the uniform distribution of In and Ga within the bulk of InxGa1-xN films. Higher In concentrations resulted in an increase of refractive indices of ternary alloys from 2.28 to 2.42 at a wavelength of 650 nm. The optical band edge of InxGa1-xN films red-shifted with increasing In content, confirming the tunability of the band edge with alloy composition. Photoluminescence measurements exhibited broad spectral features with an In concentration dependent wavelength shift and atomic force microscopy revealed low surface roughness of InxGa1-xN films with a slight increase proportional to In content.