Query: etching of semiconductor nanorods

Candidate papers:

abstract: Unexpected etching of nanocrystals, nanorods, and their heterostructures by one of the most commonly used metal precursors, metal oleates, is reported. Zn oleate is shown to etch CdS nanorods anisotropically, where the length decreases without a significant change in the diameter. Sodium oleate enhances the etch rate, whereas oleic acid alone does not cause etching, indicating the importance of the countercation on the rate of oleate induced etching. Subsequent addition of Se precursors to the partially etched nanorods in Zn oleate solution can lead to epitaxial growth of CdSe particles rather than the expected ZnSe growth, despite an excess amount of Zn precursors being present. The composition of this epitaxial growth can be varied from CdSe to ZnSe, depending on the amount of excess oleic acid or the reaction temperature. Similar tuning of composition can be observed when starting with collinear CdSe/CdS/CdSe rod/rod/rod heterostructures and spherical CdS (or CdSe/CdS core/shell) nanocrystals. Conversion of collinear rod/rod/rod structures to barbells and interesting rod growth from nearly spherical particles among other structures can also result due to the initial etching effect of metal oleates. These observations have important implications on our understanding of nanocrystal heterostructure synthesis and open up new routes to varying the composition and morphology of these materials.
author_names: Nuri Oh

Moonsub Shim
title: Metal Oleate Induced Etching and Growth of Semiconductor Nanocrystals, Nanorods, and Their Heterostructures.
venue: Journal of the American Chemical Society
year: 2016

abstract: The size and shape of CdSe nanorods, CdSe tetrapods, and CdS nanowires were tailored by chemical and photochemical etchings in chloromethane solvents. Nanocrystals were synthesized by colloidal growth, and their sizes and shapes were visualized by transmission electron microscopy before and after etching. Crystal structures were confirmed by X ray diffraction, and optical properties were monitored during etching. Chemical etching with tributylphosphine preferentially shortens the length of nanocrystals, whereas photochemical etching with both primary alkylamine and tributylphosphine reduces the diameter more than the length. The surface of etched nanocrystals was characterized by X ray photoelectron spectroscopy, and the etching products dissolved in solvent were analyzed by matrix free laser desorption ionization mass spectrometry. Spectroscopic results suggest that the chloride ion is the active species: Chloride ions are generated either by chemical activation of chloromethane solvents with tributylpho.
author_names: Sung Jun Lim

Wonjung Kim

Sunghan Jung

Jongcheol Seo

Seung Koo Shin
title: Anisotropic Etching of Semiconductor Nanocrystals
year: 2011

abstract: Vertically aligned ZnO nanorods were grown on a SiO2/Si surface by optimization of the temperature and atmosphere for annealing of the seed. The seed layer annealed at 500 degC in vacuum provided well separated and uniform seeds which also provided the best condition to get densely packed, uniformly distributed, and vertically aligned nanorods. These nanorods grown on the substrates were used to fabricate electrolyte insulator semiconductor (EIS) devices for pH sensing. Etching of ZnO at acidic pH prevents the direct use of nanorods for pH sensing. Therefore, the nanorods functionalised with 3 aminopropyltriethoxysilane (APTES) were utilized for pH sensing and showed the pH sensitivity of 50.1 mV/pH. APTES is also known to be used as a linker to immobilize biomolecules (such as antibodies) The EIS device with APTES functionalized nanorods was used for the label free detection of prostate specific antigen (PSA) Finally, voltage shifts of 23 mV and 35 mV were observed with PSA concentrations of 1 ng/ml and 100 ng/ml, respectively.
author_names: Narendra Kumar

Sujata Senapati

Satyendra Kumar

Jitendra Kumar

Siddhartha Panda
title: Functionalized vertically aligned ZnO nanorods for application in electrolyte insulator semiconductor based pH sensors and label free immuno sensors
year: 2016

abstract: The growth of ZnO nanorods by directly etching Zn foil through a low temperature aqueous method has been demonstrated. The as obtained ZnO nanorod possesses a single crystalline structure. The morphologies of ZnO nanostructures are sensitive to a series of growth parameters. Room temperature photoluminescence property of the as synthesised ZnO nanorods shows a strong ultraviolet emission peak at 379 nm. The present work demonstrates the feasibility of the growth of semiconductor nanorods by directly etching the substrate.
author_names: Ying Lei

Jing Wang

Fengyu Qu

Hui Li

Xiang Wu
title: Facile approach to ZnO nanorods by directly etching zinc substrate
year: 2012

abstract: The capability of noble metal nanoparticles (NPs) as efficient charge transfer mediators to stimulate Schottky junction triggered charge flow in multifarious photocatalysis has garnered enormous attention in the past decade. Nevertheless, fine tuning and controllable fabrication of a directional charge transport channel in metal/semiconductor heterostructures via suitable interface engineering is poorly investigated. Here, we report the progressive fabrication of a tailor made directional charge transfer channel in Pt nanoparticles (NPs) inlaid WO3 (Pt WO3) nanocomposites via an efficient electrostatic layer by layer (LbL) self assembly integrated with a thermal reduction treatment, by which oppositely charged metal precursor ions and polyelectrolyte building blocks were intimately and alternately assembled on the WO3 nanorods (NRs) by substantial electrostatic interaction. LbL self assembly buildup and in situ self etching induced structural variation of WO3 NRs to a microsized superstructure occur simultaneously. We found that such exquisitely crafted Pt WO3 nanocomposites exhibit conspicuously enhanced and versatile photoactivities for nonselective mineralizing of organic dye pollution and reduction of heavy metal ions at ambient conditions under both visible and simulated sunlight irradiation, demonstrating a synergistic effect. This is attributed to the imperative contribution of Pt NPs as electron traps to accelerate the directional high efficiency electron transport from WO3 to Pt NPs, surpassing the confinement of electron transfer kinetics of WO3 owing to low conduction level. More intriguingly, photoredox catalysis can also be triggered simultaneously in the same reaction system. The primary in situ produced active species in the photocatalytic reactions were specifically analyzed, and underlying photocatalytic mechanisms were determined. Our work would provide a universal synthesis strategy for constructing various metal decorated semiconductor nanocomposites for widespread photocatalytic utilizations.
author_names: Huaxiang Lin

Shuai Xu

Xiaoguo Fu

Zhi-quan Wei

Ming-Hui Huang

Xin Lin

Yunhui He

Guangcan Xiao

Fang-Xing Xiao
title: Layer by Layer Self Assembly of Metal/Metal Oxide Superstructures: Self Etching Enables Boosted Photoredox Catalysis.
venue: Inorganic chemistry
year: 2020

abstract: The physical properties of inorganic nanoparticles (NPs) depend on their shape, size and composition. Noble metal NPs exhibit strong localized surface plasmon resonances (LSPR) in the visible or near IR wavelength range. Hence, metal and semiconductor NPs of different nature have found broad application in imaging and colorimetric bioanalytical assays. Gold nanorods (AuNRs) and fluorescent semiconductor quantum dots (QDs) can be employed as a highly sensitive platform to probe environmental changes through variations in their size. The longitudinal LSPR frequency demonstrated by Au NRs is highly sensitive to minute changes in the AuNR aspect ratio. The emission spectra of spherical QDs depends on their diameter and concentration. We discovered for the first time that the oxidative enzyme Horseradish Peroxidase is able to produce free radicals which oxidize AuNRs and semiconductor QDs. We introduced novel bio analytical assays based on enzymatic etching of inorganic nanoparticles. HRP is able to induce a gradual oxidation of the AuNRs in the presence of trace concentrations of H2O2 and halide ions.[1] As a consequence, other enzymatic reactions, carried out by Glucose Oxidase (GOx) can be easily coupled to the HRP activity assay, thereby allowing for the detection of different amounts of glucose. Modification of AuNRs with thiol containing organic molecules such as glutathione and thiocholine hinders enzymatic etching of AuNR. Higher concentrations of thiol containing molecules in the reaction mixture gradually decrease the rate of enzymatic etching. Interestingly, the decrease in the rate of AuNR shortening can be easily monitored by UV Vis spectroscopy, through changes in the longitudinal LSPR band, highly sensitive to variations in AuNR aspect ratio. This effect can be applied to develop the novel optical assays for acetylcholine esterase (AChE) activity (Figure 1) The biocatalytic hydrolysis of acetylthiocholine by AChE yields thiocholine, which prevents enzymatic AuNR etching in the presence of HRP. 2 We also descovered a facile, mild and inexpensive enzymatic etching method for resizing of CdS QDs. It was found out that the biocatalytic process involving bromide, HRP and H2O2 decreased the size of semiconductor CdS QDs. Thus, this phenomenon can be applied to resizing of semiconductor CdS QDs under mild physiological conditions and rapid and sensitive detection of H2O2 and HRP (Figure 2) It was proven that CdS QDs immobilized on polyvinyl chloride microspheres can be etched biocatalytically too. Thus, we introduced a new platform for optical detection of analytes based on etching of semiconductor NPs. 3 References [1] Saa L, Coronado Puchau M, Pavlov V, Liz Marzan LM, Nanoscale. 6(13) (2014) 7405. [2] Saa L, Grinyte L, Liz Marzan LM, Pavlov V. manuscript in preparation. [3] Grinyte R, Saa L, Garai Ibabe G, Pavlov V, Chem. Commun. 51, (2015),17152.
author_names: Laura Saa

Ruta Grynite

Marc Coronado-Puchaua
title: Enzymatic etching of nonoparticles in biosensing
year: 2016

abstract: Operational stability and sensitivity are key issues in the practical application thin film transistor (TFT) of sensors, and the interdigital electrode is an important element that can be applied to TFT. In this study, a completely transparent interdigital electrode was printed on the glass plated with indium tin oxide (ITO) material using a laser etching machine. The produced interdigital electrode has the characteristics of high density, small line spacing, high sensitivity, and laser etching can be large. The amplitude reduces the production time of the device. Use a semiconductor tester to test the electrical transfer characteristics of the interdigital electrodes. The photoelectric generation spectrum and absorption spectrum of the interdigital electrode array plated with indium gallium zinc oxide (IGZO) material were tested. After plated with IGZO material, the ability to absorb light was greatly enhanced. The interdigital electrodes plated with IGZO material can be applied to the driving and test circuits of flexible wearable spectroscopic industrial detection sensors. It can amplify the circuit signal. After being plated with IGZO material, the power consumption of the circuit can be greatly reduced, and the measurement with low power consumption, high stability and high accuracy can be realized.
author_names: Zhenwu Tang

Zhaohai Liu

Zhi Tao

Wen-Jian Kuang
title: Fully Transparent TFT Sensor Array with IGZO/Nanorods Enhancing Structure
venue: 2021 IEEE 4th International Conference on Electronics Technology (ICET)
year: 2021

abstract: Single crystalline a Fe2O3 nanorods were prepared by a simple and direct hydrothermal method in large quantities. The 1, 2 propanediamine played the role of shape control agent for the formation of a Fe2O3 nanorods. The characteristics and the evolution mechanism of a Fe2O3 nanorods were investigated in detail. As reaction time prolonged, the hydrogen ions generated by the hydrolysis of Fe3+ could etch the surface of a Fe2O3 nanorods and resulted in the eroded a Fe2O3 nanorods formation. HRTEM results demonstrated that the eroded a Fe2O3 nanorods have rough edges and corners which leading to higher photodegradation ability. Absorption spectra and photocurrent responses indicated that the eroded a Fe2O3 nanorods have a narrow bandgap and higher photocurrent response, which were benefit for absorbing photons and inhibiting the recombination of photogenerated charges. It is expected that the etching of semiconductor materials is an effective way to design the photocatalysts with a high performance, and the a Fe2O3 nanorods with high visible light photocatalytic activity could find potential applications in the field of environmental management.
author_names: Xiaole Yan

Yiduo Wu

Dingding Li

Jie Hu

Gang Li

Pengwei Li

Huabei Jiang

Wendong Zhang
title: Synthesis and evolution of a Fe2O3 nanorods for enhanced visible light driven photocatalysis
venue: Journal of Materials Science
year: 2018

abstract: GaN/InGaN multiple quantum wells (MQW) is a promising material for high efficiency solid state lighting. Ultrafast optical pump probe spectroscopy is an important characterization technique for examining fundamental phenomena in semiconductor nanostructure with sub picosecond resolution. In this study, ultrafast exciton and charge carrier dynamics in GaN/InGaN MQW planar layer and nanorod are investigated using femtosecond transient absorption (TA) techniques at room temperature. Here nanorods are fabricated by etching the GaN/InGaN MQW planar layers using nanosphere lithography and reactive ion etching. Photoluminescence efficiency of the nanorods have been proved to be much higher than that of the planar layers, but the mechanism of the nanorod structure improvement of PL efficiency is not adequately studied. By comparing the TA profile of the GaN/InGaN MQW planar layers and nanorods, the impact of surface states and nanorods lateral confinement in the ultrafast carrier dynamics of GaN/InGaN MQW is revealed. The nanorod sidewall surface states have a strong influence on the InGaN quantum well carrier dynamics. The ultrafast relaxation processes studied in this GaN/InGaN MQW nanostructure is essential for further optimization of device application.
author_names: Weijian Chen

Xiaoming Wen

Michael Latzel

Jianfeng Yang

Shujuan Huang

Santosh Shrestha

Robert J Patterson

Silke H Christiansen

Gavin Conibeer
title: Ultrafast carrier dynamics in GaN/InGaN multiple quantum wells nanorods
venue: Micro Nano Materials, Devices, and Applications
year: 2018

abstract: We report a hybrid solar cell based on well aligned crystalline silicon nanorods (SiNRs) and an organic semiconductor, 2,2',7,7' Tetrakis (N,N di 4 methoxyphenylamino) 9,9' spirobifluorene (Spiro OMeTAD) in a core sheath heterojunction structure. The device is formed by spin coating Spiro OMeTAD on SiNRs array fabricated by electroless chemical etching. A silver grid on a conductive poly (3,4 ethylene dioxythiophene) polystyrenesulfonate layer is used as the top transparent anode. A power conversion efficiency of 10.3% has been obtained for a 1 cm2 cell with 0.35 um long SiNRs. The high efficiency and simple solution process used suggest that such devices are promising for developing low cost and high efficiency SiNRs/organic solar cells.
author_names: Lining He

Changyun Jiang

Donny Jiancheng Lai

Hao Wang
title: Highly efficient Si nanorods/organic hybrid core sheath heterojunction solar cells
year: 2011