Studies of electrical and crystal properties of ALD grown ZnO

Aluminium doped ZnO (AZO) is an interesting low cost transparent conducting oxide with further use as inorganic transport layer in multilayer solar cells as well as sensors. Here we present our work on atomic layer deposited (ALD) thin films where with optimized growth conditions we can maintain resistivity below 10-3 Ωcm even in 50-65 nm thin films grown at low temperatures (530 K) We discuss the influence of crystallographic texture for ALD grown films by comparing plain glass, Al2O3 c-plane, and Al2O3 a-plane substrates

Structure and morphology of spinel MgFe2O4 nanoparticles for water purification

In this work, spinel magnesium ferrite MgFe2O4 nanoparticles were synthesized by convential sol-gel methods. The study was focused on obtaining nanoparticles with the maximum content of specified ferrites, nanosized and uniform particles, with high crystallinity for water purification application...

Crystallographic characterisation of ultra-thin, or amorphous transparent conducting oxides:the case for raman spectroscopy.

The electronic and optical properties of transparent conducting oxides (TCOs) are closely linked to their crystallographic structure on a macroscopic (grain sizes) and microscopic (bond structure) level. With the increasing drive towards using reduced film thicknesses in devices and growing interest in amorphous TCOs such as n-type InGaZnO 4 (IGZO), ZnSnO 3 (ZTO), p-type Cu x CrO 2 , or ZnRh 2 O 4 , the task of gaining in-depth knowledge on their crystal structure by conventional X-ray diffraction-based measurements are becoming increasingly difficult. We demonstrate the use of a focal shift based background subtraction technique for Raman spectroscopy specifically developed for the case of transparent thin films on amorphous substrates. Using this technique we demonstrate, for a variety of TCOs CuO, a-ZTO, ZnO:Al), how changes in local vibrational modes reflect changes in the composition of the TCO and consequently their electronic properties

Growth of ZnO:Al by atomic layer deposition: deconvoluting the contribution of hydrogen interstitials and crystallographic texture on the conductivity

© 2019 Elsevier B.V. Aluminium doped ZnO (AZO) is an interesting low cost transparent conducting oxide with further use as an inorganic transport layer in multilayer solar cells. Here we present our work on atomic layer deposited (ALD) thin films where, with optimised growth conditions, we can obtain resistivities of 1 × 10−3 Ωcm even in 50–80 nm thin films grown at low temperatures (250 °C). We discuss the influence of crystallographic texture for ALD grown films by comparing plain glass, c-plane Al2O3, and a-plane Al2O3 substrates. We show that the doping mechanism in ALD grown AZO is more complex than for e.g. sputtered material as a substantial hydrogen interstitial related background doping occurs. We compare results from as grown samples with those briefly annealed at 320 °C in nitrogen. This process leads to an increased Hall mobility due to improved grain boundary passivation, but reduced carrier concentration due to partial loss of hydrogen interstitials

Studies of electrical and crystal properties of ALD grown ZnO

Aluminium doped ZnO (AZO) is an interesting low cost transparent conducting oxide with further use as inorganic transport layer in multilayer solar cells as well as sensors. Here we present our work on atomic layer deposited (ALD) thin films where with optimized growth conditions we can maintain resistivity below 10-3 Ωcm even in 50-65 nm thin films grown at low temperatures (530 K) We discuss the influence of crystallographic texture for ALD grown films by comparing plain glass, Al2O3 c-plane, and Al2O3 a-plane substrates

Structure and morphology of spinel MgFe2O4 nanoparticles for water purification

In this work, spinel magnesium ferrite MgFe2O4 nanoparticles were synthesized by convential sol-gel methods. The study was focused on obtaining nanoparticles with the maximum content of specified ferrites, nanosized and uniform particles, with high crystallinity for water purification application...

Pulsed cathodoluminescence of WS2 nanocrystals at various electron excitation energy densities: Defect induced sub-band gap emission

Abstract Pulsed cathodoluminescence spectra and luminescence decay kinetics of WS2 nanocrystals were studied under a high energy electron pulse excitation. Increasing electron energy density inputs to the WS2 nanocrystals lead to enhancement of the electron-hole number and their lifetimes. The maximum luminescence intensity is reached for the highest electron energy dose. The electrons, interacting with WS2 nanocrystals, form defect vacancies, wherein excited electron-holes create bound excitons which further recombine as a distinct sub-band gap emission. The lifetime of bound excitons does not depend on increasing electron doses due to the limitation of the enhancing number of bound excitons by increasing density of defects, which are radiative recombination active centers. The number of bound excitons, i.e. luminescence intensity, is proportional to the density of defects, which can be tuned by electron doses. Micro-photoluminescence measurements of the WS2 monolayer showed formation of excitons and trions