• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.130-133
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• 2010

Although many structures based on $SnO_2$ nanowires have been demonstrated, there is a limitation towards practical application due to the unwanted contact potential between the metal electrode and the $SnO_2$ nanowire. This is mostly due to the presence of the native oxide layer that acts as an insulator between the metal contact and the nanowire. In this study the contact properties between Ti/Au contacts and a single $SnO_2$ nanowire was compared to the electrical properties of a contact without the oxide layer. RIE(Reactive Ion Etching) is used to selectively remove the oxide layer from the contact area. The $SnO_2$ nanowires were synthesized by chemical vapor deposition (CVD) and dispersed on a $Si/Si_3N_4$ substrate. The Ti/Au (20nm/100nm) electrodes were formed bye-beam lithography, e-beam evaporation and a lift-off process.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.4
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• pp.91-97
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• 2023

Electrochemical (EC) CO₂ reduction is a promising method to convert CO₂ into valuable hydrocarbon fuels and chemicals ecofriendly. Here, we report on a facile method to synthesize surface-controlled SnO₂/Cu(OH)₂ nanowires (NWs) and its EC reduction of CO₂ to HCOOH and CO. The SnO₂/Cu(OH)₂ NWs (-16 mA/cm²) showed superior electrochemical performance compared to Cu(OH)2 NWs (-6 mA/cm²) at -1.0 V (vs. RHE). SnO₂/Cu(OH)₂ NWs showed the maximum Faradaic efficiency for conversion to HCOOH (58.01 %) and CO (29.72 %). The optimized catalyst exhibits a high C1 Faradaic efficiency stable electrolysis for 2 h in a KHCO₃ electrolyte. This study facilitates the potential for the EC reduction of CO₂ to chemical fuels.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.1
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• pp.1-8
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• 2017

Catalytic synthesis and properties of ${\beta}-Ga_2O_3$ nanowires grown by metal organic chemical vapor deposition are reported. Au, Ni and Cu catalysts were suitable for the growth of $Ga_2O_3$ nanowires under our experimental conditions. The $Ga_2O_3$ nanowires grown by using Au, Ni and Cu catalysts showed different growth rates and morphologies in each case. We found the $Ga_2O_3$ nanowires were grown by the Vapor-Solid (VS) process when Ni was used as a catalyst while the Vapor-Liquid-Solid (VLS) was a dominant process in case of Au and Cu catalysts. Also, we found nanowires showed different optical properties depend on catalytic metals. On the other hand, for the cases of Ti, Sn and Ag catalysts, nanowires could not be obtained under the same condition of Au, Cu and Ni catalytic synthesis. We found that these results are related to the different characteristics of each catalyst, such as, melting points and phase diagrams with gallium metal.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.269-269
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• 2010

$SnO_2$ 나노선은 n-type의 전기적 특성과 우수한 광 특성을 보이며, 전자소자, 광소자 뿐 아니라 다양한 종류의 가스 센서 등에 응용되고 있다. 그러나 $SnO_2$ 나노선은 공기중에서 전기적으로 불안정한 특성을 보이며, 도핑을 하지 않은 나노선 소자에서는 전자의 모빌러티가 높지 않다는 단점을 갖고 있다. 이를 개선하고자 본 연구에서는 화학기상증착법 (Chemical Vapor Deposition)으로 Sb을 도핑한 $SnO_2$ 나노선을 성장하여 전계방출효과 트랜지스터 (field effect transistor: FET)를 제작하여 전기적 특성과 UV 반응성의 변화를 측정하였다. Sb 도핑 양을 늘려감에 따라 전기적 특성이 반도체 특성에서 점점 금속 특성으로 변하는 것과 게이트 전압의 영향을 적게 받는 것을 확인하였다. 또한 도핑을 해준 $SnO_2$ 나노선의 경우 UV 반응과 회복 시간이 기존에 비하여 크게 감소하여 UV 센서에 더욱 적합해진 것을 확인하였다. 또한, 슬라이딩 트랜스퍼 공정을 이용하여 나노선을 원하는 기판에 정렬된 상태로 전이할 때 도핑한 나노선은 표면특성의 변화로 정렬도가 크게 감소하는 것을 확인하였고, 기판에 윤활제를 사용하여 정렬도를 높일 수 있었다.

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

• Proceedings of the Korean Vacuum Society Conference
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• 2006.08a
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• pp.198-198
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• 2006

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.274-274
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• 2010

최근 들어 나노선을 이용한 pn 접합 소자 연구 결과가 매우 활발하게 보고되고 있다. 그러나, 서로 다른 두 종류의 나노선으로 pn 접합 어레이 구조의 소자를 제작할 때, 나노선을 원하는 위치에 정렬하는 기술상의 어려움이 큰 걸림돌이 된다. 본 연구에서는 p-CNT와 n-$SnO_2$ 나노선을 이용한 pn 접합 어레이 구조를 제작할 수 있는 독창적인 공정기술을 제안한다. 먼저 $SiO_2$가 300 nm 성장된 Si 기판을 선택적으로 패터닝하여 BOE (6:1) 용액으로 $SiO_2$ 층을 80 nm 정도 선택적으로 에칭한 후, 선택적으로 에칭된 표면에 슬라이딩 장비를 이용하여 화학기상증착법(chemical vapor deposition: CVD)으로 성장된 n-$SnO_2$ 나노선을 전이시킨다. 그 다음 thermal tape를 이용하여 CVD 법으로 성장된 랜덤 네트워크 형태의 CNT를 $SnO_2$ 나노선이 전이된 기판 위에 전이 시킨다. 이때 성장된 CNT 필름 중 금속성 나노선을 통한 전하 이동을 감소시키기 위해, 촉매로 사용되는 페리틴의 농도를 낮춰서 전체적인 CNT의 농도를 줄이는 방법을 이용하였다. 따라서, 성장된 CNT 필름은 별도의 후처리 없이 p-형의 반도체성을 보였다. 제작된 pn-소자는 정류비가 ~103 인 정류특성을 보였으며, 254 nm 파장의 UV lamp를 조사하여 광전류가 발생하는 것을 확인하였다. 연구결과는 이종의 나노선 접합에 의한 다이오드 응용과 UV 센서응용 가능성을 보여준다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.273-273
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• 2010

Recently, extensive research on hetero-junction arrays has been reported owing to its unique band gaps dissimilar to that of homo-junctions. These hetero-junction devices can be used in laser, solar cells, and various sensors. We report on the facile method to fabricate SWCNTs/SnO2 nanowires hetero-junction arrays on flexible polyimide substrate. Each SWCNT field effect transistor (FET) and SnO2 nanowire FET exhibits the purely p- and n-type charactersistics with ohmic contact properties. Such formed pn-junctions showed rectification behaviors reproducibly with a rectification ratio of ${\sim}3{\times}103$ at 1 V and ideality factors about 12. The pn-junctions also showed a good gate modulation behavior.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.241-241
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• 2014

$SnO_2-core/Zn-shell$ heteronanowires were fabricated by a two-step process: thermal evaporation of Sn powders and employing a sputtering technique with a Zn target. X-ray diffraction, high-resolution transmission electron microscopy, and EDX spectra coincidentally indicated that the shell layer comprised the Zn phase. From Gaussian deconvolution studies, we observed that photoluminescence (PL) spectra consisted of yellow, green, and ultraviolet (UV) emission bands, regardless of shell-coating. We speculated the possible mechanisms of these emission peaks.

• Journal of the Korean Ceramic Society
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• v.48 no.1
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• pp.94-98
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• 2011

A Sn-doped $In_2O_3$ (ITO) nanowire photoelectrode was produced using a simple metal evaporation method at low synthesis temperature (< $540^{\circ}C$). The nanowire electrodes have large surface area compared with that of flat ITO thin film, and show low electrical resistivity of $5.6{\times}10^{-3}{\Omega}cm$ at room temperature. In order to apply ITO nanowires to the photoelectrodes of dye-sensitized solar cell (DSSC), those surfaces were modified by $TiO_2$ nanoparticles using a chemical bath deposition (CBD) method. The conversion efficiency of the fabricated $TiO_2$/ITO nanostructure-based DSSC was obtained at 1.4%, which was increased value by a factor of 6 than one without ITO nanowires photoelectrode. This result is attributed to the large surface area and superior electrical property of the ITO nanowires photoelectrode, as well as the structural advantages, including short diffusion length of photo-induced electrons, of the fabricated $TiO_2$/ITO nanostructure-based DSSC.