Synthesis of Ga-Doped ZnO Nanorods by Hydrothermal Method and Their Application to Ultraviolet Photodetector

Young, Sheng-Joue; Chiou, Chia-Lin; Liu, Yi-Hsing; Ji, Liang‐Wen

doi:10.3390/inventions1010003

Cited by 15 publications

(5 citation statements)

References 22 publications

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“…These results show that the GZO NS photosensor exhibits an improved performance by increasing carrier concentration. [57][58][59][60] To explain this phenomenon, a schematic of the photoconduction mechanism in the presence of high-density hole-trap states on the NS surface is presented in Fig. 32.…”

Section: Performance Of Uv Photosensors With Al- Ga- and In-doped Zmentioning

confidence: 99%

Review—Growth of Al-, Ga-, and In-Doped ZnO Nanostructures via a Low-Temperature Process and Their Application to Field Emission Devices and Ultraviolet Photosensors

Young¹,

Yang²,

Lai³

2016

J. Electrochem. Soc.

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In recent decades, ZnO-based nanostructures have attracted considerable attention because of their various possible morphologies, large surface-to-volume ratios, non-toxicity, easy synthesis, low cost, and excellent physical properties for fabricating highperformance electronic, magnetic, and optoelectronic devices. This review article focuses on recent advances in Al-, Ga-, and In-doped ZnO nanostructures, including a brief overview of the hydrothermal method and aqueous solution methods. Among these strategies, ZnO nanostructures synthesized via the hydrothermal method exhibits distinct advantages, such as low growth temperature, low cost, and large resultant surface area, as well as applicability in fabricating field emission (FE) devices and photosensors. FE devices have gained widespread attention for their applications in flat-panel displays and other electronic devices, such as microwave amplifiers, X-ray tubes, cathode-ray tube monitors, and electron microscopes. FE devices are influenced by interrelated factors, including emitter geometry, crystal structure, conductivity, work function, spatial distribution of emitting centers, and nanostructure density of nanorods. An applied electric field bends the surface barrier to form a triangular barrier, and the excited electrons tunnel easily to generate the emission current. A large number of excited electrons are stored at the tips of nanowires, thereby causing subsequent point discharge that reduces the electric field. ZnO-based ultraviolet (UV) photosensors are frequently used in environmental monitoring, securing space-to-space communication, flame sensing, and chemical biological analysis. ZnO UV photosensors are used to manufacture various structures, such as p-n heterojunction photodiodes, metal-semiconductor-metal photosensors, and Schottky photodiodes. The resistance of pure n-type ZnO nanostructure is high. ZnO nanostructures are commonly doped with other elements. To improve the electrical properties of ZnO nanostructures, donor dopants for ZnO, such as group III elements (Al, Ga, and In), can be used. The optical and electrical properties of fabricated ZnO optoelectronic devices can also be improved by doping with group III elements. Furthermore, as a material with a direct bandgap (3.37 eV), ZnO can easily absorb wavelengths in the UV range. Thus, illumination under UV can enhance the FE capacity of ZnO nanowires. Methods that enhance the performance of field emitters and photosensors are introduced in this review paper. We hope that this review paper can provide a useful reference to those who are interested in ZnO-based field emission devices and photosensors. ZnO-based nanostructures comprise a highly promising key group of II-VI semiconductor materials. ZnO-based nanostructures have numerous advantages, including a wide bandgap of 3.37 eV, a direct bandgap structure at room temperature, a large exciton binding energy of approximately 60 meV, thermal stability at room temperature (significantly higher than that of GaN), non-toxicity, manufactu...

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Section: Performance Of Uv Photosensors With Al- Ga- and In-doped Zmentioning

confidence: 99%

Review—Growth of Al-, Ga-, and In-Doped ZnO Nanostructures via a Low-Temperature Process and Their Application to Field Emission Devices and Ultraviolet Photosensors

Young¹,

Yang²,

Lai³

2016

J. Electrochem. Soc.

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“…Compared with the ZPD samples, the ZPD-G samples clearly showed better responsivity and remarkably higher rejection ratio for UV/visible, which were better than or at least substantially equivalent to those of the other ZnO-based nanostructures; these values are summarized in Table I. According to the above experiments, the excellent PD performance of the ZPD-G NSs could be attributed to three reasons: [37][38][39][40]…”

Section: Resultsmentioning

confidence: 80%

Improvement of the UV-Sensing Performance of Ga-Doped ZnO Nanostructures via a Wet Chemical Solution at Room Temperature

Chu

Young

Chu

et al. 2021

ECS J. Solid State Sci. Technol.

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In this investigation, ultraviolet (UV) photodetectors (PDs) were fabricated from zinc oxide (ZnO) and Ga-doped ZnO nanostructures on a Corning glass substrate by a simple wet chemical solution method at room temperature. The prepared devices contained two-dimensional (2-D) nanosheet (NS) structures, which could provide a large surface-area-to-volume ratio for UV-sensing. The ZnO and Ga-doped ZnO materials were respectively named ZPD and ZPD-G. All of the samples revealed a hexagonal wurtzite structure and grew preferentially along the (002) crystal plane. Compared with the photoluminescence (PL) spectrum of the ZPD NSs, the corresponding spectra of the ZPD-G NSs in the 380 nm region and green emission were clearly red-shifted and the number of oxygen vacancies slightly decreased. Under 380 nm UV illumination and a 3 V applied bias, the ZnO UV PDs doped with Ga elements exhibited much higher photoresponsivity and stability compared with the un-doped ZnO PDs, indicating good electrical performance. The ZPD-G samples possessed higher rise and recovery times compared with the ZPD samples; this finding could be attributed to the ability of the former to generate numerous electrons.

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“…This is achieved by trivalent extrinsic dopant atoms such as Al, Ga, and In, acting as donors when substituting for Zn sites in the ZnO lattice. Extrinsic doping proved to play a crucial role in improving the properties of ZnO NRs [ 24 , 25 , 26 , 27 , 28 ]. Among these, Al dopants can reach very high n-type conductivity without deterioration in optical transmittance [ 29 , 30 , 31 ], and therefore lend themselves to be ideal candidates for such use.…”

Section: Introductionmentioning

confidence: 99%

“…There have been multiple attempts to synthesize vertically aligned Ga-doped ZnO NRs [ 27 , 34 ] and AZO NR arrays [ 31 , 32 , 35 ] on different substrates. Out of the techniques employed, a hydrothermal method (or chemical bath deposition) appears advantageous owing to its low cost and low growth temperature [ 9 , 30 ].…”

Section: Introductionmentioning

confidence: 99%

pH Controlled Nanostructure and Optical Properties of ZnO and Al-Doped ZnO Nanorod Arrays Grown by Microwave-Assisted Hydrothermal Method

et al. 2022

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The low-temperature microwave-assisted hydrothermal method was used to successfully grow pure and Al-doped ZnO (AZO) nanorod (NR) arrays on glass substrates. The combined effects of doping and pH on the structural properties, surface chemistry, and optical properties of all samples were investigated. Thermodynamic-based simulations of the growth solution were performed and a growth mechanism, that considers the effects of both the pH and Al-doping, is proposed, and discussed. Tuning the solution pH is key parameter to grow well-aligned, single crystal, highly packed, and high aspect ratio nanorod arrays. Moreover, the optical absorption in the visible range is enhanced by controlling the pH value. The PL spectra reveal a shift of the main radiative emission from the band-to-band into a transition involving deep defect levels of Zinc interstitial Zni. This shift is caused by an enhancement of the non-radiative components (phonon relaxation) at high pH values. The production of well-ordered ZnO and AZO nanorod arrays with visible-active absorption/emission centers would increase their potential use in various applications.

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Synthesis of Ga-Doped ZnO Nanorods by Hydrothermal Method and Their Application to Ultraviolet Photodetector

Cited by 15 publications

References 22 publications

Review—Growth of Al-, Ga-, and In-Doped ZnO Nanostructures via a Low-Temperature Process and Their Application to Field Emission Devices and Ultraviolet Photosensors

Review—Growth of Al-, Ga-, and In-Doped ZnO Nanostructures via a Low-Temperature Process and Their Application to Field Emission Devices and Ultraviolet Photosensors

Improvement of the UV-Sensing Performance of Ga-Doped ZnO Nanostructures via a Wet Chemical Solution at Room Temperature

pH Controlled Nanostructure and Optical Properties of ZnO and Al-Doped ZnO Nanorod Arrays Grown by Microwave-Assisted Hydrothermal Method

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