Experimental and numerical study on growth of high-quality ZnO single-crystal microtubes by optical vapor supersaturated precipitation method

Wang, Qiang; Yan, Yinzhou; Zeng, Yong; Jiang, Yijian

doi:10.1016/j.jcrysgro.2016.12.020

Cited by 19 publications

(8 citation statements)

References 29 publications

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“…30,31 A ZnO ceramic precursor rod that is 6 mm in diameter and 50 mm in length was first pre-sintered in a vertical Molysili furnace at 700°C for 10 h. Then, the top of the precursor rod was polished to a cone with a height of 3-5 mm. The precursor rod was fixed in a four-mirror optical image furnace (10000H-HR-I-VPO-PC manufactured by Crystal Systems, Hokuto, Yamanashi, Japan) equipped with four 1500 W halogen lamps as heating sources.…”

Section: Experimental Procedures Fabrication Of Utw-zno Microtubesmentioning

confidence: 99%

“…The microtube diameter and wall thickness can be precisely controlled by varying the growth parameters according to the pilot experiments. 30,31 To obtain the ZnO microtubes with Novel UTW-ZnO microtube as a potential core component material/structure Q Wang et al a wall thinner than 1 μm, the lamp power was set to be 65% (of 1500 W), and the temperature holding time in the growth was increased to 2.5 h for sufficient redecomposition. The as-grown and mechanically detached microtubes from the ceramic precursor rod are shown in the insets of Figure 1a.…”

Section: Experimental Procedures Fabrication Of Utw-zno Microtubesmentioning

confidence: 99%

“…30 The process parameters were then optimized to grow thin-walled microtubes that were a 100 μm in diameter and a few microns thick in the facet wall with a high finish quality. 31 Although the thin-walled ZnO microtube possesses a hexagonal cross-section, the optical properties as a microcavity have not yet been studied.…”

Section: Introductionmentioning

confidence: 99%

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A novel ultra-thin-walled ZnO microtube cavity supporting multiple optical modes for bluish-violet photoluminescence, low-threshold ultraviolet lasing and microfluidic photodegradation

et al. 2017

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ZnO optical microcavities have shown great promise as a potential core component material/structure for ultraviolet lasers, lightemitting diodes and photonic sensors because of their outstanding optoelectronic properties. Here, we report a novel ultra-thinwalled ZnO (UTW-ZnO) microtube cavity with a wall thickness of~750 nm, supporting multiple types of optical modes, including in-tube Fabry-Perot modes, in-wall Fabry-Perot modes and wave-guided whispering gallery modes (WG-WGMs). The free-exciton recombination rate and exciton-exciton collisions are promoted in the cavity. The intensities of near-band edge (ultravoilet (UV) light) and X-band (blue light) emission are therefore increased at least one order of magnitude in the temperature range of 0-500°C. Meanwhile, the temperature-sensitive multicolor luminescence of the UTW-ZnO microtubes in the visible band from near-white to bluish-violet is demonstrated for the first time. Low-threshold UV lasing is also achieved in the UTW-ZnO microtube by WG-WGMs, where the excitation threshold is down to 5.50 μW. Furthermore, light harvesting in the microtube cavity is beneficial to boosting the ZnO catalytic performance for photodegradation of organic dyes. The UTW-ZnO microtube exhibits compatibility to microfluidic channels for recyclable on-chip degradation. The present work provides new opportunities to design novel tubular wide-bandgap semiconductor devices for a variety of optoelectronic applications in micro/ nanophotonics.

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Section: Experimental Procedures Fabrication Of Utw-zno Microtubesmentioning

confidence: 99%

Section: Experimental Procedures Fabrication Of Utw-zno Microtubesmentioning

confidence: 99%

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A novel ultra-thin-walled ZnO microtube cavity supporting multiple optical modes for bluish-violet photoluminescence, low-threshold ultraviolet lasing and microfluidic photodegradation

et al. 2017

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“…A halogen lamp 44870 WFL (Osram, Munich, Bavaria, Germany) was selected as an image light source to assist image acquisition in order to obtain an image from the 435-950 nm region. The selected lamp had a brightness of 680 lm of 50 W and a color temperature of 3000 K. Halogen lamps have a broad spectrum from visible light to infrared regions [33]. For image analysis using the NDVI, a band-pass filter from the 435 to 950 nm region of BP-Series (Midwest Optical Systems, Palatine, Illinois, USA) was used.…”

Section: Hardware Compositionmentioning

confidence: 99%

Comparing Performances of CNN, BP, and SVM Algorithms for Differentiating Sweet Pepper Parts for Harvest Automation

et al. 2021

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For harvest automation of sweet pepper, image recognition algorithms for differentiating each part of a sweet pepper plant were developed and performances of these algorithms were compared. An imaging system consisting of two cameras and six halogen lamps was built for sweet pepper image acquisition. For image analysis using the normalized difference vegetation index (NDVI), a band-pass filter in the range of 435 to 950 nm with a broad spectrum from visible light to infrared was used. K-means clustering and morphological skeletonization were used to classify sweet pepper parts to which the NDVI was applied. Scale-invariant feature transform (SIFT) and speeded-up robust features (SURFs) were used to figure out local features. Classification performances of a support vector machine (SVM) using the radial basis function kernel and backpropagation (BP) algorithm were compared to classify local SURFs of fruits, nodes, leaves, and suckers. Accuracies of the BP algorithm and the SVM for classifying local features were 95.96 and 63.75%, respectively. When the BP algorithm was used for classification of plant parts, the recognition success rate was 94.44% for fruits, 84.73% for nodes, 69.97% for leaves, and 84.34% for suckers. When CNN was used for classifying plant parts, the recognition success rate was 99.50% for fruits, 87.75% for nodes, 90.50% for leaves, and 87.25% for suckers.

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“…Our previous work has demonstrated the stable acceptor-rich ZnO (A-ZnO) microrods/tubes grown by temperature-gradient-free optical vapor supersaturation precipitation (OVSP) (Hu et al, 2018a(Hu et al, , 2018bHuang et al, 2019;Wang et al, 2016Wang et al, , 2017aWang et al, , 2017bWang et al, , 2019b. The Zn vacancy (V Zn ) acted as an acceptor level, activating donor-acceptor-pair (DAP) recombination with intrinsic compensation donors, i.e., oxygen vacancy (V O ), for visible photoluminescence (PL) emission up to 773 K (Wang et al, 2017a).…”

Section: Introductionmentioning

confidence: 99%

Current-Induced Thermal Tunneling Electroluminescence in a Single Highly Compensated Semiconductor Microrod

et al. 2020

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Here we demonstrate a novel and robust mechanism, termed as ''current-induced Joule heating activated thermal tunneling excitation,'' to achieve electroluminescence (EL) by the hot electron-hole-pair recombination in a single highly compensated semiconductor microrod. The radiative luminescence is electrically excited under ambient conditions. The current-induced Joule heating reduces the thermal tunneling excitation threshold of voltage down to 8 V and increases the EL effi-ciency~4.4-fold at 723 K. We interpret this novel phenomenon by a thermal tunneling excitation model corrected by electric-induced Joule heating effect. The mechanism is confirmed via theoretical calculation and experimental demonstration, for the first time. The color-tunable EL emission is also achieved by regulation of donor concentration. This work opens up new opportunities for design of novel multi-color light-emitting devices by homogeneous defect-engineered semiconductors in future.

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Experimental and numerical study on growth of high-quality ZnO single-crystal microtubes by optical vapor supersaturated precipitation method

Cited by 19 publications

References 29 publications

A novel ultra-thin-walled ZnO microtube cavity supporting multiple optical modes for bluish-violet photoluminescence, low-threshold ultraviolet lasing and microfluidic photodegradation

A novel ultra-thin-walled ZnO microtube cavity supporting multiple optical modes for bluish-violet photoluminescence, low-threshold ultraviolet lasing and microfluidic photodegradation

Comparing Performances of CNN, BP, and SVM Algorithms for Differentiating Sweet Pepper Parts for Harvest Automation

Current-Induced Thermal Tunneling Electroluminescence in a Single Highly Compensated Semiconductor Microrod

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