Oxidized Nano-Porous-Silicon Buffer Layers for Suppressing the Visible Photoresponsivity of ZnO Ultraviolet Photodetectors on Si Substrates

This paper demonstrated the fabrication and optoelectronic characteristics of ZnO ultraviolet (UV) photodetectors fabricated on Si substrates with oxidized nano-porous-Si (ONPS) buffer layers. ONPS layers were prepared on the surfaces of Si substrates by use of an electrochemical anodization technique following a rapid-thermal-oxidation process. Experimental results indicated that application of ONPS buffer layers not only improved the crystallinty of the deposited ZnO thin films but also greatly restricted the visible-to-infrared photoresponse that was generated from the light absorption of Si substrates. The developed ZnO-on-ONPS photodiodes achieved high photoresponsivity for the incident UV light of 300 ∼ 400 nm and got a large photo-to-dark current ratio up to 104 at wavelength of 375 nm under a bias of 5 V. Therefore, ZnO on ONPS provides a highly potential approach for the development of low-cost visible-blind UV photodetectors.

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Buffer Layers for Ferroelectric-Based Infra-Red Detectors on Si Grown by a Novel CVD Method

MRS Proceedings ◽

10.1557/proc-299-291 ◽

1994 ◽

Vol 299 ◽

Author(s):

Gregory T. Stauf ◽

Peter C. VanBuskirk ◽

Peter S. Kirlin ◽

Walter P. Kosar

Keyword(s):

Low Cost ◽

Infrared Detector ◽

Liquid Solution ◽

Buffer Layers ◽

Single Source ◽

Detector Arrays ◽

Si Substrates ◽

Materials Integration ◽

Stoichiometry Control ◽

Detector Materials

AbstractFerroelectrics such as PbTiO3 and BaSrTiO3 are promising candidates for pyroelectric infrared detector materials. Integration of ferroelectric thin films on Si will permit fabrication of low-cost infrared detector arrays, but a buffer layer will be required to reduce interactions with the substrate. For this reason we have investigated MOCVD of MgAl2O4 and yttria-stabilized zirconia (YSZ) buffer layers on both Si and MgO. A single source molecule, magnesium dialuminum isopropoxide (Mg[Al(OCH(CH3)2)4]2), was used for deposition of the MgAl2O4, the first time to our knowledge that well characterized multi-metal oxide films have been deposited by CVD from a single-source compound. Both EDAX and RBS showed film stoichiometries consistent with the elemental ratio in the source. A novel liquid solution-based flash vaporization technique was used to transport the organometallic sources into the reactor, providing both excellent reproducibility and ease of stoichiometry control and deposition rate. Highly oriented [100] MgAl2O4 was grown on MgO, and [100] YSZ was grown on MgO and Si. Degree of preferred orientation of the YSZ was found to be dependent on oxygen partial pressure, both for the MgO and Si substrates.

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Transparent Ultraviolet Photodetectors Based on Ga2O3 Electrospun Nanowires

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.281.710 ◽

2018 ◽

Vol 281 ◽

pp. 710-715

Author(s):

Muhammad Shahid ◽

Tian Jun Li ◽

Meng Fei Zhang ◽

Jing Cheng ◽

Yan Xing ◽

...

Keyword(s):

Uv Light ◽

Low Cost ◽

Electrospun Nanofibers ◽

High Transparency ◽

Highly Sensitive ◽

Electrospinning Method ◽

Low Dimensional ◽

Ultraviolet Photodetectors ◽

High Photosensitivity ◽

Excellent Stability

Ultraviolet photodetectors (PDs) based on low-dimensional (LD) gallium oxide nanofibers were synthesized and assembled by a low cost and scalable electrospinning method. Highly uniaxially aligned nanofibers were used to assemble photodetectors. Photoconductive investigations indicate that the prepared photodetectors (PDs) are highly sensitive to ultraviolet (UV) light. The prepared photodetectors have shown a high photosensitivity (103), fast photoresponse, excellent stability, and reproducibility under the illumination of UV light 254 nm. These electrospun nanofibers have also shown a high transparency (<85%) in the visible light 400-700 nm range. The high transparency of these nanobelts demonstrates their use for invisible UV photosensors.

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Irradiation Response of Graphene Enhanced Gallium Nitride Metal-Semiconductor-Metal Ultraviolet Photodetectors

MRS Proceedings ◽

10.1557/opl.2015.397 ◽

2015 ◽

Vol 1746 ◽

Author(s):

Heather C. Chiamori ◽

Nicholas Broad ◽

Chetan Angadi ◽

Ruth Miller ◽

Caitlin Chapin ◽

...

Keyword(s):

Gallium Nitride ◽

Uv Light ◽

Harsh Environments ◽

Voltage Response ◽

Uv Photodetectors ◽

Metal Semiconductor Metal ◽

Current Voltage ◽

Msm Photodetector ◽

Corrosive Environments ◽

Ultraviolet Photodetectors

ABSTRACTRadiation-tolerant materials, sensors and electronics can enable lightweight space subsystems with reduced packaging requirements and increased operation lifetimes. Such technology can be used within extreme harsh environments related to space exploration, radiation medicine and power generation (combustion and nuclear). Gallium nitride (GaN), a ceramic semiconductor material, is a candidate material due to its stability within high-radiation, high-temperature and chemically corrosive environments. In addition, the wide bandgap of GaN (3.4 eV) can be leveraged for ultraviolet (UV) wavelength photodetection. In metal-semiconductor-metal (MSM) photodetector architectures using Schottky contacts, transparent electrodes (e.g., graphene) can increase sensitivity and improve overall device response. Here we present fabrication and characterization of GaN-based UV photodetectors using graphene electrodes irradiated up to 200 krad total ionizing dose (TID) then tested under UV light and dark conditions. For current-voltage measurements taken at 90, 120 and 200 krad TID, the current-voltage response does not vary significantly. From 90 to 120 krad TID, the responsivity shifts by 2% before dropping off at 200 krad TID. These initial findings suggest that graphene/GaN MSM UV photodetectors can provide robust operation within extreme harsh environments.

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Influence of MBE Growth Conditions on Dislocation Densities of GaAs/Ge Epilayers Grown on Silicon Substrates

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100118692 ◽

1985 ◽

Vol 43 ◽

pp. 364-365

Author(s):

K.M. Hones ◽

P. Sheldon ◽

B.G. Yacobi ◽

A. Mason

Keyword(s):

High Efficiency ◽

Lattice Mismatch ◽

Low Cost ◽

Growth Conditions ◽

Nonradiative Recombination ◽

Device Structure ◽

Si Substrates ◽

Transmission Electron ◽

Dislocation Densities ◽

Dislocation Type

There is increasing interest in growing epitaxial GaAs on Si substrates. Such a device structure would allow low-cost substrates to be used for high-efficiency cascade- junction solar cells. However, high-defect densities may result from the large lattice mismatch (∼4%) between the GaAs epilayer and the silicon substrate. These defects can act as nonradiative recombination centers that can degrade the optical and electrical properties of the epitaxially grown GaAs. For this reason, it is important to optimize epilayer growth conditions in order to minimize resulting dislocation densities. The purpose of this paper is to provide an indication of the quality of the epitaxially grown GaAs layers by using transmission electron microscopy (TEM) to examine dislocation type and density as a function of various growth conditions. In this study an intermediate Ge layer was used to avoid nucleation difficulties observed for GaAs growth directly on Si substrates. GaAs/Ge epilayers were grown by molecular beam epitaxy (MBE) on Si substrates in a manner similar to that described previously.

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Advanced Treatment of Coking Wastewater by Oxidation Process Using Pyrite and Hydrogen Peroxide

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.726-731.2521 ◽

2013 ◽

Vol 726-731 ◽

pp. 2521-2525

Author(s):

Zhi Yong Zhang ◽

De Li Wu

Keyword(s):

Hydrogen Peroxide ◽

Oxidation Process ◽

Low Cost ◽

Oxygen Demand ◽

Utilization Efficiency ◽

Advanced Treatment ◽

Coking Wastewater ◽

Second Stage ◽

Potential Alternative ◽

High Utilization

Coking wastewater is a kind of recalcitrant wastewater including complicate compositions. Advanced treatment of coking wastewater by Fenton-Like reaction using pyrite as catalyst was investigated in this paper. The results show that the chemical oxygen demand (COD) of coking wastewater decreased significantly by method of coagulation combined with two-stage oxidation reaction. COD of wastewater can decrease from 250mg/l to 45mg/l after treatment, when 2g/L pyrite was used in each stage oxidation and the dosage of hydrogen peroxide (H2O2) is 0.2ml/l for first stage treatment, 0.1ml/l for second stage treatment respectively. The pyrite is effective to promote Fenton-Like reaction with low cost due to high utilization efficiency of H2O2, moreover, catalyst could be easily recovered and reused. The Fenton-Like reaction might be used as a potential alternative to advanced treatment of recalcitrant wastewater.

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High Performance Flexible Visible-Blind Ultraviolet Photodetectors with Two-Dimensional Electron Gas Based on Unconventional Release Strategy

ACS Nano ◽

10.1021/acsnano.0c10374 ◽

2021 ◽

Author(s):

Yi-Yu Zhang ◽

Yi-Xiong Zheng ◽

Jun-Yu Lai ◽

Jung-Hun Seo ◽

Kwang Hong Lee ◽

...

Keyword(s):

High Performance ◽

Electron Gas ◽

Two Dimensional ◽

Dimensional Electron ◽

Two Dimensional Electron Gas ◽

Dimensional Electron Gas ◽

Ultraviolet Photodetectors ◽

Visible Blind ◽

Release Strategy

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Effects of the Sputtering Time of AlN Buffer Layer on the Quality of ZnO Thin Films

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.881-883.1117 ◽

2014 ◽

Vol 881-883 ◽

pp. 1117-1121 ◽

Cited By ~ 1

Author(s):

Xiang Min Zhao

Keyword(s):

Thin Films ◽

Buffer Layer ◽

Rf Magnetron Sputtering ◽

Buffer Layers ◽

Zno Thin Films ◽

Zno Films ◽

Si Substrates ◽

Atomic Force ◽

Structure Morphology ◽

Aln Buffer

ZnO thin films with different thickness (the sputtering time of AlN buffer layers was 0 min, 30 min,60 min, and 90 min, respectively) were prepared on Si substrates using radio frequency (RF) magnetron sputtering system.X-ray diffraction (XRD), atomic force microscope (AFM), Hall measurements setup (Hall) were used to analyze the structure, morphology and electrical properties of ZnO films.The results show that growth are still preferred (002) orientation of ZnO thin films with different sputtering time of AlN buffer layer,and for the better growth of ZnO films, the optimal sputtering time is 60 min.

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Antioxidant Determination with the Use of Carbon-Based Electrodes

Chemosensors ◽

10.3390/chemosensors9040072 ◽

2021 ◽

Vol 9 (4) ◽

pp. 72

Author(s):

Aurelia Magdalena Pisoschi ◽

Aneta Pop ◽

Florin Iordache ◽

Loredana Stanca ◽

Liviu Bilteanu ◽

...

Keyword(s):

Surface Area ◽

Oxidation Process ◽

Low Cost ◽

Oxidative Enzymes ◽

Adaptation Mechanisms ◽

Chain Breaking ◽

Nanomolar Range ◽

Quench Singlet Oxygen ◽

Carbon Based

Antioxidants are compounds that prevent or delay the oxidation process, acting at a much smaller concentration, in comparison to that of the preserved substrate. Primary antioxidants act as scavenging or chain breaking antioxidants, delaying initiation or interrupting propagation step. Secondary antioxidants quench singlet oxygen, decompose peroxides in non-radical species, chelate prooxidative metal ions, inhibit oxidative enzymes. Based on antioxidants’ reactivity, four lines of defense have been described: Preventative antioxidants, radical scavengers, repair antioxidants, and antioxidants relying on adaptation mechanisms. Carbon-based electrodes are largely employed in electroanalysis given their special features, that encompass large surface area, high electroconductivity, chemical stability, nanostructuring possibilities, facility of manufacturing at low cost, and easiness of surface modification. Largely employed methods encompass voltammetry, amperometry, biamperometry and potentiometry. Determination of key endogenous and exogenous individual antioxidants, as well as of antioxidant activity and its main contributors relied on unmodified or modified carbon electrodes, whose analytical parameters are detailed. Recent advances based on modifications with carbon-nanotubes or the use of hybrid nanocomposite materials are described. Large effective surface area, increased mass transport, electrocatalytical effects, improved sensitivity, and low detection limits in the nanomolar range were reported, with applications validated in complex media such as foodstuffs and biological samples.

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Defect Reduction in GaAs Epilayers on Si Substrates Using Strained Layer Superlattices

MRS Proceedings ◽

10.1557/proc-91-99 ◽

1987 ◽

Vol 91 ◽

Cited By ~ 9

Author(s):

N. El-Masry ◽

N. Hamaguchi ◽

J.C.L. Tarn ◽

N. Karam ◽

T.P. Humphreys ◽

...

Keyword(s):

Thermal Annealing ◽

Rapid Thermal Annealing ◽

Buffer Layers ◽

Threading Dislocations ◽

Defect Reduction ◽

Strained Layer ◽

Si Substrates ◽

Density Of Dislocations ◽

Strained Layer Superlattice ◽

Strained Layer Superlattices

ABSTRACTInxGa11-xAs-GaAsl-yPy strained layer superlattice buffer layers have been used to reduce threading dislocations in GaAs grown on Si substrates. However, for an initially high density of dislocations, the strained layer superlattice is not an effective filtering system. Consequently, the emergence of dislocations from the SLS propagate upwards into the GaAs epilayer. However, by employing thermal annealing or rapid thermal annealing, the number of dislocation impinging on the SLS can be significantly reduced. Indeed, this treatment greatly enhances the efficiency and usefulness of the SLS in reducing the number of threading dislocations.

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