Thermal annealing effects on the dynamic photoresponse properties of Al-doped ZnO nanowires network

Kim, Kang-Pil; Chang, Daeic; Lim, Sang Kyoo; Lee, Soo-Keun; Lyu, Hong-Kun; Hwang, Dae‐Kue

doi:10.1016/j.cap.2011.03.065

Cited by 20 publications

(12 citation statements)

References 17 publications

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“…In addition, annealing in oxygen improves the surface condition of the nanorod arrays, which increases their affinity for the oxygen molecules. The sensitivity of the sensor has been reported to be correlated with the oxygen adsorption and desorption processes [12,33,50]. In the dark, oxygen molecules tend to adsorb onto the nanorod surfaces by capturing free electrons and producing adsorbed oxygen ions, as shown by the following equation:…”

Section: Resultsmentioning

confidence: 99%

“…However, annealing is also a ZnO surface treatment process that could remove surface defects and contamination, thereby improving the surface condition of ZnO [29][30][31]. Although the annealing temperature is widely reported to influence the performance of the UV photoconductive sensor [32][33][34][35], the effects of annealing under different environments have rarely been reported in terms of the performance of ZnO nanorodarray-based UV photoconductive sensors.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Annealing Environments on the Solution‐Grown, Aligned Aluminium‐Doped Zinc Oxide Nanorod‐Array‐Based Ultraviolet Photoconductive Sensor

Mamat

Khalin

Mohammad

et al. 2012

Journal of Nanomaterials

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We have fabricated metal-semiconductor-metal- (MSM-) type ultraviolet (UV) photoconductive sensors using aluminium- (Al-) doped zinc oxide (ZnO) nanorod arrays that were annealed in different environments: air, oxygen, or a vacuum. The Al-doped ZnO nanorods had an average diameter of 60 nm with a thickness of approximately 600 nm that included the seed layer (with thickness~200 nm). Our results show that the vacuum-annealed nanorod-array-based UV photoconductive sensor has the highest photocurrent value of 2.43 × 10-4 A. The high photocurrent is due to the high concentration of zinc (Zn) interstitials in the vacuum-annealed nanorod arrays. In contrast, the oxygen-annealing process applied to the Al-doped ZnO nanorod arrays produced highly sensitive UV photoconductive sensors, in which the sensitivity reached 55.6, due to the surface properties of the oxygen-annealed nanorods, which have a higher affinity for oxygen adsorption than the other samples and were thereby capable of reducing the sensor’s dark current. In addition, the sensor fabricated using the oxygen-annealed nanorod arrays had the lowest rise and decay time constants. Our result shows that the annealing environment greatly affects the surface condition and properties of the Al-doped ZnO nanorod arrays, which influences the performance of the UV photoconductive sensors.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of Annealing Environments on the Solution‐Grown, Aligned Aluminium‐Doped Zinc Oxide Nanorod‐Array‐Based Ultraviolet Photoconductive Sensor

Mamat

Khalin

Mohammad

et al. 2012

Journal of Nanomaterials

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“…Our X-ray diffraction result is consistent with those in previous studies [47][48][49][50][51], in which crystallinity is improved with respect to annealing temperature. Photoresponse ( on / off ) increases as annealing temperature increases [52][53][54][55][56][57][58]. In ZnO-type materials, photoresponse is generally caused by oxygen desorption and adsorption process originating from either a bulk-or surface-related process [52,59,60].…”

Section: Resultsmentioning

confidence: 99%

“…This phenomenon may occur possibly because crystallinity is improved, defect ratio decreases, and barrier height increases at maximum postannealing temperatures [55]. This improved crystallinity also creates a well-interconnected network [53] of Sn-doped ZnO nanorods, thereby enhancing the electronic flow along the nanorod/nanowire axis [63,64]. However, electrons experience resistance along the nanorod axis at low annealing temperatures; as a result, photoresponse is decreased.…”

Section: Resultsmentioning

confidence: 99%

Structural, Optical, Electrical, and Photoresponse Properties of Postannealed Sn‐Doped ZnO Nanorods

Humayun

Kashif

Hashim

2013

Journal of Nanomaterials

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Tin (Sn) doped ZnO nanorods were synthesized on glass substrate using a sol-gel method. The synthesized nanorods were postannealed at 150, 350, and 500°C. The surface morphologies of Sn-doped ZnO nanorods at different postannealing temperatures were studied using scanning electron microscope (SEM). XRD results show that as the postannealing temperature increased from 150°C to 500°C, thec-axis orientation becomes stronger. Refractive indices and dielectric constants were calculated on the basis of different relationships by utilizing bandgap values. These bandgap values were obtained in terms of optical absorption by using a UV-Visible spectrophotometer. The enhancing effects of annealing temperatures on electrical properties were observed in terms of current-to-voltage measurements. Resistivity decreases as postannealing temperature increases from 150°C to 500°C. Annealed samples were evaluated for UV-sensing application. The samples exhibit a responsivity of 1.7 A/W.

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“…For example, Kim et al reported that water molecules and residual carbon from the fabrication process could be effectively desorbed from the surface of a ZnO nanowire during the annealing process (Kim et al, 2011). As a consequence, oxygen molecules from the air could occupy the existing defect sites more easily, which contributed to a faster photocurrent decay, higher sensitivity, and faster response when the UV light was turned off.…”

mentioning

confidence: 99%

ZnO Nanorod Arrays Synthesised Using Ultrasonic-Assisted Sol-Gel and Immersion Methods for Ultraviolet Photoconductive Sensor Applications

Mamat¹,

Khusaimi²,

Musa³

et al. 2012

Nanorods

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Thermal annealing effects on the dynamic photoresponse properties of Al-doped ZnO nanowires network

Cited by 20 publications

References 17 publications

Effects of Annealing Environments on the Solution‐Grown, Aligned Aluminium‐Doped Zinc Oxide Nanorod‐Array‐Based Ultraviolet Photoconductive Sensor

Effects of Annealing Environments on the Solution‐Grown, Aligned Aluminium‐Doped Zinc Oxide Nanorod‐Array‐Based Ultraviolet Photoconductive Sensor

Structural, Optical, Electrical, and Photoresponse Properties of Postannealed Sn‐Doped ZnO Nanorods

ZnO Nanorod Arrays Synthesised Using Ultrasonic-Assisted Sol-Gel and Immersion Methods for Ultraviolet Photoconductive Sensor Applications

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