Search query: porous silicon doped zinc oxide

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abstract: The interface between photoactive biological materials with two distinct semiconducting electrodes is challenging both to develop and analyze. Building off of our previous work using films of photosystem I (PSI) on p doped silicon, we have deposited a crystalline zinc oxide (ZnO) anode using confined plume chemical deposition (CPCD) We demonstrate the ability of CPCD to deposit crystalline ZnO without damage to the PSI biomaterial. Using electrochemical techniques, we were able to probe this complex semiconductor biological interface. Finally, as a proof of concept, a solid state photovoltaic device consisting of p doped silicon, PSI, ZnO, and ITO was constructed and evaluated.
author_names: Jeremiah C Beam

Gabriel LeBlanc

Evan A Gizzie

Borislav L Ivanov

David R Needell

Melinda J Shearer

G Kane Jennings

Charles M Lukehart

David E Cliffel
title: Construction of a Semiconductor Biological Interface for Solar Energy Conversion: p Doped Silicon/Photosystem I/Zinc Oxide.
venue: Langmuir the ACS journal of surfaces and colloids
year: 2015

abstract: Morphological and optical characteristics of radio frequency sputtered zinc aluminum oxide over porous silicon (PS) substrates were studied before and after irradiating composite films with 130 MeV of nickel ions at different fluences varying from 1 x 1012 to 3 x 1013 ions/cm2. The effect of irradiation on the composite structure was investigated by scanning electron microscopy, X ray diffraction (XRD) photoluminescence (PL) and cathodoluminescence spectroscopy. Current voltage characteristics of ZnO PS heterojunctions were also measured. As compared to the granular crystallites of zinc oxide layer, Al doped zinc oxide (ZnO) layer showed a flaky structure. The PL spectrum of the pristine composite structure consists of the emission from the ZnO layer as well as the near infrared emission from the PS substrate. Due to an increase in the number of deep level defects, possibly oxygen vacancies after swift ion irradiation, PS Al doped ZnO nanocomposites formed with high porosity PS are shown to demonstrate a broadening in the PL emission band, leading to the white light emission. The broadening effect is found to increase with an increase in the ion fluence and porosity. XRD study revealed the relative resistance of the film against the irradiation, i.e. the irradiation of the structure failed to completely amorphize the structure, suggesting its possible application in optoelectronics and sensing applications under harsh radiation conditions.
author_names: Yogesh Kumar

Manuel Herrera-Zaldivar

Sion Federico Olive-Mendez

Fouran Singh

Xavier Mathew

Vivechana Agarwal
title: Modification of optical and electrical properties of zinc oxide coated porous silicon nanostructures induced by swift heavy ion
venue: Nanoscale Research Letters
year: 2012

abstract: Abstract An in situ calcination strategy has been developed for the synthesis of porous zinc oxide/N doped carbon (ZnO/NC) polyhedrons, in which zeolitic imidazolate framework 8 (ZIF 8) serves as the precursor. The ZnO/NC polyhedrons with a hierarchical architecture possess a high specific surface area of 390.7 m 2 g 1 high nitrogen content (19.99 at% and robust pore structures. The porous N doped carbon frameworks can not only increase the electronic conductivity of ZnO, but also provide interior space for the fast diffusion of Li ions and accommodate the volume variations during the charge and discharge cycles. When evaluated for lithium storage capacity, the hierarchical ZnO/NC polyhedrons exhibit high reversible discharge capacity (834.3 mAh g 1 at the initial low rate of 0.5C, 1C 978 mA g 1 superior rate performance (399.2 mAh g 1 at 5C and 253.5 mAh g 1 at 10C) and excellent cycling stability (677.9 mAh g 1 at 1C after 400 cycles) The reasons are explored in terms of the well confined primary nanocrystals (5 nm) and the finely constructed interconnected pores of the N doped carbon networks, which facilitate the fast and effective transfer of Li ions and electrons, and accommodate the large volume expansions.
author_names: Zhenfang Zhou

Kun Zhang

Jinghao Liu

Hongrui Peng

Guicun Li
title: Comparison study of electrochemical properties of porous zinc oxide/N doped carbon and pristine zinc oxide polyhedrons
year: 2015

abstract: Abstract We report the room temperature cathodoluminescence and photoluminescence of swift ion irradiated (130 MeV Nickel ion) porous silicon zinc oxide nanocomposites. The evolution of a broad and flat emission band from 1.5 to 3.5 eV is demonstrated. Annealing effect of irradiation is found to result in a relative increase in the band edge emission. Emission wavelength can be tuned in the complete visible range by changing the substrate characteristics.
author_names: Yogesh Kumar

M Herrera

Fouran Singh

Sion Federico Olive-Mendez

Dinakar Kanjilal

Shiv Kumar

Vivechana Agarwal
title: Cathodoluminescence and photoluminescence of swift ion irradiation modified zinc oxide porous silicon nanocomposite
year: 2012

abstract: Sol gel grown polycrystalline Al doped zinc oxide (AZO) thin films have been deposited on Si wafers, microscopy slide glass and fluorine doped tin oxide coated glass substrates using the spin coating technique. The atomic ratio of Al:Zn in the films is 0.2. From the X ray diffraction investigations it is found that the preferential growth of (100) reflection peak has taken place in the 450, 550 and 600 degC annealed films. Scanning electron microscopic study has shown that the films contain well defined grains arranged in a closely packed array. The resistivity of the 500 degC annealed film is measured to be 5 x 10 1 O cm. The films have exhibited excellent optical transmittance 90% in the 400 1100 nm wavelength range. Refractive indices (n 1.9 1.95) of the films on Si wafer are independent of the annealing temperature. Thickness of the films produced at 4000 rpm is in the range of 58 62 nm. The refractive index and thickness of these films are nearly appropriate to cause destructive interference after reflection from front emitters of solar cells. These films have demonstrated a reflectivity value of about 3% at a wavelength of 700 nm. The AZO coated silicon solar cells possess Voc and Isc values of 573 mV and 237 mA, respectively.
author_names: Amitabh Verma

Firoz Shah Tuglak Khan

Dinesh Kumar

M Kar

B C Chakravarty

Sukhvir Singh

Mushahid Husain
title: Sol gel derived aluminum doped zinc oxide for application as anti reflection coating in terrestrial silicon solar cells
year: 2010

abstract: Abstract Aerogel nanopowder of calcium doped zinc oxide (ZnO:Ca) was synthesized by modified sol gel method. In this process, hydrolyses was slowly released and followed by a thermal drying in supercritical conditions or ethyl alcohol. The obtained nanopowder was characterized by various techniques such as X ray diffraction (XRD) scanning electron microscopy (SEM) transmission electron microscopy (TEM) Cathodoluminescence (CL) and photoluminescence (PL) XRD data showed that Ca doped ZnO sample has a hexagonal wurtzite structure with a slight distortion of ZnO lattice and no extra secondary phases, suggesting the substitution of Ca ions in the ZnO structure. SEM micrograph shows spherical microparticles having a rough porous fine grained. From TEM micrograph, the samples are composed by single particles having an inhomogeneous size distribution, with most of them having a dimension in the range between 20 and 50 nm. This powder presents a strong photoluminescence band in the visible range. From photoluminescence excitation (PLE) the energy position of the obtained PL band depends on the wavelength of excitation. The luminescence results are also confirmed by cathodoluminescence technique and suggests the presence of photo active centers in ZnO:Ca as deduced from new published works for visible photo activated gas sensors and photo catalysis of dyes degradation. We hope that this work provides some answers to the scientific community concerning the effect of doping in the creation of optical active centers in ZnO, promising for many technological applications.
author_names: Lassaad El Mir
title: Luminescence properties of calcium doped zinc oxide nanoparticles
year: 2017

abstract: We report the obtaining of electroluminescent devices (ELD) from porous silicon (PS) and indium doped zinc oxide (ZnO:In) junctions. PS presented photoluminescence (PL) in the visible region of the electromagnetic spectrum. ZnO:In thin film was obtained by dip coating technique. SEM images and IR measurements showed the incorporation of the ZnO:In in the PS structure. Once obtained, the device was optically and electrically characterized. The ELD showed emission in the visible (450 850 nm) and infrared region (900 1200 nm) where it was electrically polarized. The visible emission was detected as luminescent spots on the surface. Electrical characterization was carried out by current voltage (I V) curves. The I V curves showed rectifying behavior. It was related to the quenching of the EL with the process that takes place in the PS when it was immersed in the precursor solution of the ZnO:In.
author_names: F Severiano

Godofredo Garcia

Luis Castaneda

V Lopez Gayou
title: Porous Silicon and Indium Doped Zinc Oxide Junctions: Synthesis, Characterization, and Application to Electroluminescent Devices
year: 2017

abstract: The luminescent properties of zinc oxide (ZnO) and nanostructured porous silicon (PSi) make these materials very appealing for photoemission applications. The current study reports on the fabrication of a composite of ZnO and nanostructured porous silicon micropatterns (ZnO PSi micropatterns) onto heavily doped silicon surfaces. The proposed composite micropattern is devoted to the future development of light emitting diodes. The fabrication of the ZnO PSi micropatterns was carried out in a two step process. (1) A regular hexagonal micropattern of a photoresist/ZnO stack was fabricated by UV lithography on crystalline silicon substrates. (2) Before being lifted off the photoresist, nanostructured PSi micropatterns were fabricated by electrochemically etching the exposed areas of the silicon substrate. Subsequently, wet etching of the photoresist was carried out for the final development of the composite ZnO and PSi micropatterns. Further, thin films of ZnO and nanostructured PSi layers were characterized. In particular, their photoluminescent properties were analyzed, as well as their morphology and composition. The experimental PL results show that the ZnO layers have emission broadbands centered at (2.63 eV, blue) while the PSi layers show a band centered at (1.71 eV, red) Further, the emission peaks from the PSi layers can be tuned by changing their fabrication conditions. It was observed that the properties of the ZnO thin films are not influenced by either the surface morphology of PSi or by its PL emissions. Therefore, the PL properties of the composite ZnO PSi micropatterns are equivalent to those featuring the addition of PSi layers and ZnO thin films. Accordingly, broadband optical emissions are expected to arise from a combination between the ZnO layer (blue band) and PSi (red band) Furthermore, the electrical losses associated with the PSi areas can be greatly reduced since ZnO is in contact with the Si surface. As a result, the proposed composite micropatterns might be attractive for many solid state lighting applications, such as light emitting diodes.
author_names: Rehab Ramadan

Vicente Torres-Costa

Raul Jose Martin-Palma
title: Fabrication of Zinc Oxide and Nanostructured Porous Silicon Composite Micropatterns on Silicon
year: 2020

abstract: Electroluminescent devices (ELD) based on junctions of indium doped zinc oxide (ZnO:In) and porous silicon layers (PSL) are presented in this work. PSL with different thicknesses and photoluminescent emission, around 680 nm, were obtained by anodic etching. PSL were coated with a ZnO:In film which was obtained by ultrasonic spray pyrolysis technique. Once obtained, this structure was optically and electrically characterized. When the devices were electrically polarized they showed stable electroluminescence (EL) which was presented as dots scattered over the surface. These dots can be seen with the naked eye. The observed EL goes from the 410 to 1100 nm, which is formed by different emission bands. The EL emission in the visible region was around 400 to 750 nm, and the emission corresponding to the infrared part covers the 750 to 1150 nm. The electrical characterization was carried out by current voltage curves (I V) which show a rectifying behavior of the devices. Observed electroluminescent dots are associated with the electron hole injection into quantized states in PS as well as the emission from the ZnO:In film.
author_names: F Severiano

Godofredo Garcia

Luis Castaneda

J M Gracia-Jimenez

Heberto Gomez-Pozos

Jose Alberto Luna-Lopez
title: Electroluminescent devices based on junctions of indium doped zinc oxide and porous silicon
year: 2014

abstract: Abstract In this study we obtained electroluminescent devices (ELD) based on junctions of indium doped zinc oxide (ZnO:In) and porous silicon layers (PSL) The PSL were obtained by electrochemical etching with different types and resistivities of silicon wafers. In the visible part of the electromagnetic spectrum, the porous silicon (PS) exhibits photoluminescence (PL) that is centered around 680 nm. Once the devices were obtained, they were optically and electrically characterized. The PSL were coated with ZnO:In film, which was gotten by the ultrasonic spray pyrolysis technique (USP) When the devices were electrically polarized they showed optical response in the regions corresponding to the visible and infrared band of the electromagnetic spectrum. The observed electroluminescence (EL) in the visible region goes from 400 to 750 nm and the corresponding emission of the infrared part is around 750 1150 nm. The devices presented luminescent spots on the surface which were visible to the naked eye. The analysis of the results shows that the emission source in the visible part is attributed to the filaments present in the PS, and also to the ZnO:In films and the emission in the infrared part is associated to the silicon substrate. The electrical characterization was carried out by current voltage curves I V that show in the devices a rectifying behavior.
author_names: F Severiano

Godofredo Garcia

Luis Castaneda
title: Study of the electroluminescent properties of crystalline silicon wafers in devices based on junctions of indium doped zinc oxide and porous silicon
year: 2014