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Ultraviolet photodetectors based on ZnO nanorods-seed layer effect and metal oxide modifying layer effect.

Zhou H, Fang G, Liu N, Zhao X - Nanoscale Res Lett (2011)

Bottom Line: In this paper, we discussed the effect of metal oxide modifying layer on the performance of UV PDs pre- and post-deposition annealing at 300°C, respectively.For Schottky barrier UV PDs with different seed layers, the MgZnO seed layer-PDs without metal oxide coating showed bigger responsivity and larger detectivity (Dλ*) than those of PDs with ZnO seed layer, and the reason was illustrated through energy band theory and the electron transport mechanism.Also the ratio of D254* to D546* was calculated above 8 × 102 for all PDs, which demonstrated that our PDs showed high selectivity for detecting UV light with less influence of light with long wavelength.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Electronic Science and Technology and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China. gjfang@whu.edu.cn.

ABSTRACT
Pt/ZnO nanorod (NR) and Pt/modified ZnO NR Schottky barrier ultraviolet (UV) photodetectors (PDs) were prepared with different seed layers and metal oxide modifying layer materials. In this paper, we discussed the effect of metal oxide modifying layer on the performance of UV PDs pre- and post-deposition annealing at 300°C, respectively. For Schottky barrier UV PDs with different seed layers, the MgZnO seed layer-PDs without metal oxide coating showed bigger responsivity and larger detectivity (Dλ*) than those of PDs with ZnO seed layer, and the reason was illustrated through energy band theory and the electron transport mechanism. Also the ratio of D254* to D546* was calculated above 8 × 102 for all PDs, which demonstrated that our PDs showed high selectivity for detecting UV light with less influence of light with long wavelength.

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The dependences of photocurrents on operating time for PDs with different metal oxide coatings under UV light (365 nm) with power density of 16.7 μW/cm2 at the bias of 2 V. (a) Before annealing; (b) after annealing at 300°C.
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Figure 3: The dependences of photocurrents on operating time for PDs with different metal oxide coatings under UV light (365 nm) with power density of 16.7 μW/cm2 at the bias of 2 V. (a) Before annealing; (b) after annealing at 300°C.

Mentions: For PDs, the response and recovery times are a very important factor for applications. The dependences of photocurrent on operating time for the PDs with different oxides under UV light (365 nm) with power density of 16.7 μW/cm2 at the bias of 2 V are shown in Figure 3a (before annealing) and Figure 3b (annealed at 300°C), respectively. From Figure 3a, under 365-nm UV illumination, the current of the PDs increases very slowly to reach saturation, and at turn off of the UV lamp, the current decreases also slowly. Also it is deduced that the response time of the PDs is all above 30 s, and the recovery time of the PDs (the photocurrent decreases 80%) is all above 50 s. For the PDs with different oxide-coating materials, the devices show enhanced UV response characteristic, but the response and recovery are all slow. After annealing, all PDs show fast response and recovery behaviors, and their response and recovery times are 3 and 4 s, respectively. For PDs with different oxide coatings, the UV response characteristic gets worse than that of PDs without metal oxide coating, which shows that the effect of metal oxide coating for Schottky contact PDs is a negative one.


Ultraviolet photodetectors based on ZnO nanorods-seed layer effect and metal oxide modifying layer effect.

Zhou H, Fang G, Liu N, Zhao X - Nanoscale Res Lett (2011)

The dependences of photocurrents on operating time for PDs with different metal oxide coatings under UV light (365 nm) with power density of 16.7 μW/cm2 at the bias of 2 V. (a) Before annealing; (b) after annealing at 300°C.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211197&req=5

Figure 3: The dependences of photocurrents on operating time for PDs with different metal oxide coatings under UV light (365 nm) with power density of 16.7 μW/cm2 at the bias of 2 V. (a) Before annealing; (b) after annealing at 300°C.
Mentions: For PDs, the response and recovery times are a very important factor for applications. The dependences of photocurrent on operating time for the PDs with different oxides under UV light (365 nm) with power density of 16.7 μW/cm2 at the bias of 2 V are shown in Figure 3a (before annealing) and Figure 3b (annealed at 300°C), respectively. From Figure 3a, under 365-nm UV illumination, the current of the PDs increases very slowly to reach saturation, and at turn off of the UV lamp, the current decreases also slowly. Also it is deduced that the response time of the PDs is all above 30 s, and the recovery time of the PDs (the photocurrent decreases 80%) is all above 50 s. For the PDs with different oxide-coating materials, the devices show enhanced UV response characteristic, but the response and recovery are all slow. After annealing, all PDs show fast response and recovery behaviors, and their response and recovery times are 3 and 4 s, respectively. For PDs with different oxide coatings, the UV response characteristic gets worse than that of PDs without metal oxide coating, which shows that the effect of metal oxide coating for Schottky contact PDs is a negative one.

Bottom Line: In this paper, we discussed the effect of metal oxide modifying layer on the performance of UV PDs pre- and post-deposition annealing at 300°C, respectively.For Schottky barrier UV PDs with different seed layers, the MgZnO seed layer-PDs without metal oxide coating showed bigger responsivity and larger detectivity (Dλ*) than those of PDs with ZnO seed layer, and the reason was illustrated through energy band theory and the electron transport mechanism.Also the ratio of D254* to D546* was calculated above 8 × 102 for all PDs, which demonstrated that our PDs showed high selectivity for detecting UV light with less influence of light with long wavelength.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Electronic Science and Technology and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China. gjfang@whu.edu.cn.

ABSTRACT
Pt/ZnO nanorod (NR) and Pt/modified ZnO NR Schottky barrier ultraviolet (UV) photodetectors (PDs) were prepared with different seed layers and metal oxide modifying layer materials. In this paper, we discussed the effect of metal oxide modifying layer on the performance of UV PDs pre- and post-deposition annealing at 300°C, respectively. For Schottky barrier UV PDs with different seed layers, the MgZnO seed layer-PDs without metal oxide coating showed bigger responsivity and larger detectivity (Dλ*) than those of PDs with ZnO seed layer, and the reason was illustrated through energy band theory and the electron transport mechanism. Also the ratio of D254* to D546* was calculated above 8 × 102 for all PDs, which demonstrated that our PDs showed high selectivity for detecting UV light with less influence of light with long wavelength.

No MeSH data available.


Related in: MedlinePlus