• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.12
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• pp.808-812
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• 2015

Highly optical transparent photoelectric devices were realized by using a transparent metal-oxide semiconductor heterojunction of p-type NiO and n-type ZnO. A functional template of ITO nanowires (NWs) was applied to this transparent heterojunction device to enlarge the light-reactive surface. The ITO NWs/n-ZnO/p-NiO heterojunction device provided a significant high rectification ratio of 275 with a considerably low reverse saturation current of 0.2 nA. The optical transparency was about 80% for visible wavelengths, however showed an excellent blocking UV light. The nanostructured transparent heterojunction devices were applied for UV photodetectors to show ultra fast photoresponses with a rise time of 8.3 mS and a fall time of 20 ms, respectively. We suggest this transparent and super-performing UV responser can practically applied in transparent electronics and smart window applications.

• Proceedings of the Materials Research Society of Korea Conference
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• 2006.11a
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• pp.17.1-17.1
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.159-160
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• 2011

• Korean Journal of Materials Research
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• v.19 no.1
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• pp.33-36
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• 2009

Inorganic-organic composite thin-film-transistors (TFTs) of ZnO nanowire/Poly(3-hexylthiophene) (P3HT) were investigated by changing the nanowire densities inside the composites. Crystalline ZnO nanowires were synthesized via an aqueous solution method at a low temperature, and the nanowire densities inside the composites were controlled by changing the ultrasonifiaction time. The channel layers were prepared with composites by spin-coating at 2000 rpm, which was followed by annealing in a vacuum at $100^{\circ}C$ for 10 hours. Au/inorganic-organic composite layer/$SiO_2$ structures were fabricated and the mobility, $I_{on}/I_{off}$ ratio, and threshold voltage were then measured to analyze the electrical characteristics of the channel layer. Compared with a P3HT TFT, the electrical properties of TFT were found to be improved after increasing the nanowire density inside the composites. The mobility of the P3HT TFT was approximately $10^{-4}cm^2/V{\cdot}s$. However, the mobility of the ZnO nanowire/P3HT composite TFT was increased by two orders compared to that of the P3HT TFT. In terms of the $I_{on}/I_{off}$ ratio, the composite device showed a two-fold increase compared to that of the P3HT TFT.

• Proceedings of the Materials Research Society of Korea Conference
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• 2008.11a
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• pp.24.2-24.2
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• 2008

• Korean Journal of Materials Research
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• v.32 no.10
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• pp.435-441
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• 2022

We report the synthesis and gas sensing properties of bare and ZnO decorated TeO₂ nanowires (NWs). A catalyst assisted-vapor-liquid-solid (VLS) growth method was used to synthesize TeO₂ NWs and ZnO decoration was performed using an Au-catalyst assisted-VLS growth method followed by a subsequent heat treatment. Structural and morphological analyses using X-ray diffraction (XRD) and scanning/transmission electron microscopies, respectively, demonstrated the formation of bare and ZnO decorated TeO₂ NWs with desired phase and morphology. NO₂ gas sensing studies were performed at different temperatures ranging from 50 to 400 ℃ towards 50 ppm NO₂ gas. The results obtained showed that both sensors had their best optimal sensing temperature at 350 ℃, while ZnO decorated TeO₂ NWs sensor showed much better sensitivity towards NO₂ relative to a bare TeO₂ NWs gas sensor. The reason for the enhanced sensing performance of the ZnO decorated TeO₂ NWs sensor was attributed to the formation of ZnO (n)/ TeO₂ (p) heterojunctions and the high intrinsic gas sensing properties of ZnO.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.7
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• pp.502-509
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• 2018

Epitaxial ZnO nanowires (NWs) were synthesized on sapphire (001) substrates using a hydrothermal process. The effects of the pH value of the precursor solution on the structural and optical properties of the resulting NWs was studied. The epitaxial relationship and the domain matching configuration between the sapphire (001) substrate and the as-grown ZnO NWs were determined using synchrotron X-ray diffraction measurements. The (002) plane of $w{\ddot{u}}rtzite$ ZnO NW grows in the surface normal direction parallel to the sapphire (001) direction. However, three types of in-plane domain matching configurations were observed, such as the on-position, $30^{\circ}$-rotated position, and ${\pm}8.5^{\circ}$-rotated position relative to the on-position, which might be attributed to inheriting the in-plane domain configuration of the ZnO seed layer.

• KIEE International Transactions on Electrophysics and Applications
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• v.2C no.6
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• pp.314-320
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• 2002

Three different ZnO nanomaterials (nanobelts, nanorods, and nanowires) were synthesized at 138$0^{\circ}C$ from ball-milled ZnO powders by a thermal evaporation procedure with an argon carrier gas without any catalysts. Transmission electron microscopy (TEM) revealed that the ZnO nanobelts are single crystalline with the growth direction perpendicular to the (010) lattice plane, and that the ZnO nanorods and nanowires are single crystalline with the growth directions perpendicular to the (001) and (110) lattice Planes, respectively. In cathodoluminescence (CL), the energy Position of the near band-edge (NBE) peak is 3.280 eV for the 100-, 250-, and 500-nm thick nanobelts, 3.262 eV for the 100- and 250-nm thick nanorods, and 3.237 eV for the 500-nm thick nanorods. The synthesized ZnO nanorods were coated conformally with aluminum oxide (Al$_2$O$_3$) material by atomic layer deposition (ALD). $Al_2$O$_3$films were then deposited on these ZnO nanorods by ALD at a substrate temperature of 300 $^{\circ}C$ using trimethylaluminum (TMA) and distilled water ($H_2O$). Transmission electron microscopy (TEM) images of the deposited ZnO nanorods revealed that 40nm-thick $Al_2$O$_3$ cylindrical shells surround the ZnO nanorods.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1297-1298
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• 2006

Omega-shaped-gate (OSG) nanowire-based field effect transistors (FETs) have been attracted recently attention due to their highdevice performance expected from theoretical simulations among nanowire-based FETs with other gate geometries. OSG FETs with the channels of ZnO nanowires were successfully fabricated in this study with photolithographic processes. In the OSG FETs fabricated on oxidized Si substrates, the channels of ZnO nanowires with diameters of about 60 nm are coated surroundingly by $Al_{2}O_{3}$ as gate dielectrics with atomic layer deposition. About 80 % of the surfaces of the nanowires coated with $Al_{2}O_{3}$ is covered with gate metal to form OSG FETs. A representative OSG FET fabricated in this study exhibits a mobility of 98.9 $cm^{2}/Vs$, a peak transconductance of 0.4 ${\mu}S$, and an Ion/Ioff ratio of $10^6$ the value of the Ion/Ioff ratio obtained from this OSG FET is the highest among nanowire-based FETs, to our knowledge. Its mobility, peak transconductance, and Ion/Ioff ratio arc remarkably enhanced by 11.5, 32, and $10^6$ times, respectively, compared with a back-gate FET with the same ZnO nanowire channel as utilized in the OSG FET.

• 한국전자현미경학회:학술대회논문집
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• 2005.05a
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• pp.59-65
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• 2005