• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.25 no.2
• /
• pp.91-95
• /
• 2012

ZnO thin films were deposited on p-type 4H-SiC substrate by pulsed laser deposition. ZnO nanowires were formed on p-type 4H-SiC substrate by furnace. Ti/Au electrodes were deposited on ZnO thin film/SiC and ZnO nanowire/SiC structures, respectively. Structural and crystallographical properties of the fabricated ZnO thin film/SiC and ZnO nanowire/SiC structures were investigated by field emission scanning electron microscope and X-ray diffraction. In this work, resistance and sensitivity of ZnO thin film/SiC gas sensor and ZnO nanowire/SiC gas sensor were measured at $300^{\circ}C$ with various CO gas concentrations (0%, 90%, 70%, and 50%). Resistance of gas sensor decreases at CO gas atmosphere. Sensitivity of ZnO nanowire/SiC gas sensor is twice as big as sensitivity of ZnO thin film/SiC gas sensor.

• 한국전자현미경학회:학술대회논문집
• /
• 2005.11a
• /
• pp.43-43
• /
• 2005

• Proceedings of the Korean Vacuum Society Conference
• /
• 2004.08a
• /
• pp.247-247
• /
• 2004

• Transactions on Electrical and Electronic Materials
• /
• v.15 no.5
• /
• pp.262-264
• /
• 2014

Pristine ZnO, 3 wt.% Ga-doped (3GZO) and 3 wt.% Ag-doped (3SZO) ZnO nanowires (NWs) were grown using the hot-walled pulse laser deposition (HW-PLD) technique. The doping of Ga and Ag in ZnO NWs was observed by analyzing the optical and chemical properties. We optimized the synthesis conditions, including processing temperature, time, gas flow, and distance between target and substrate for the growth of pristine and doped ZnO NWs. The diameter and length of pristine and doped ZnO NWs were controlled under 200 nm and several ${\mu}m$, respectively. Low temperature photoluminescence (PL) was performed to observe the optical property of doped NWs. We clearly observed the shift of the near band edge (NBE) emission by using low temperature PL. In the case of 3GZO and 3SZO NWs, the center photon energy of the NBE emissions shifted to low energy direction using the Burstein Moss effect. A strong donor-bound exciton peak was found in 3 GZO NWs, while an acceptor-bound exciton peak was found in 3SZO NWs. X-ray photoelectron spectroscopy (XPS) also indicated that the shift of binding energy was mainly attributed to the interaction between the metal ion and ZnO NWs.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.378-379
• /
• 2012

ITO 만큼 높은 전도성과 광학적 투과성을 갖는 Al-doped ZnO (AZO) 박막을 DC-Pulse magnetron sputtering을 이용하여 40 nm 두께로 증착 후 리소그라피 공정을 통해 $30{\mu}m$ 간격으로 패터닝 하였다. 간격 30 ${\mu}m$로 배열된 AZO를 촉매층으로 하는 수열합성법을 리사이클 공정을 반복하여 수행하여 ZnO 나노선을 성장시켰다. 이와 같이 AZO 전극 사이에 길이 $30{\mu}m$의 ZnO 나노선이 래터럴 구조로 연결된 소자의 $NH_3$ 가스감지 특성을 조사하였다. 합성된 나노선의 전기적, 광학적, 구조적인 특성을 분석하여 높은 가스 감지도를 예상할 수 있는 특성을 확인하였다. 제작된 가스센서를 진공 챔버에 설치 후 양 전극간에 동작전압(Operating voltage)을 1 V로 인가하여 고정한 후에 $NH_3$를 주입(Injection)과 퍼지(Purge)를 반복하며 그 주입량(10 ppm, 20 ppm, 40 ppm, 60 ppm)에 변화를 주었고, 그에 따른 전류변화를 관찰하여 $NH_3$ 가스감지특성을 평가하였다.

• Ceramist
• /
• v.20 no.4
• /
• pp.55-73
• /
• 2017

As one of the most versatile semiconductors, zinc oxide (ZnO) with one-dimensional (1-D) nanostructures has been significantly developed for the application of ultraviolet (UV) lasers, photochemical sensors, photocatalysts, and so on. Such 1-D nanowires could be easily achieved due to the anisotropic growth rate along the [0001] direction. However, such typical growth habit leads to decrease the surface area of the (0001) plane, which plays a central role in not only UV lasing action but also photocatalytic reaction. This fact lead us to develop ZnO crystal with enhanced polar surface area through crystal growth control. The purpose of this review is to provide readers a simple route to plate-type ZnO crystal with highly enhanced polar surfaces and their applications for UV-laser, photocatalyst, and antibacterial agents. In addition, we will highlight the recent study on pilot-scale synthesis of plate-type ZnO crystal for industrial applications.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2010.05a
• /
• pp.27.2-27.2
• /
• 2010

In recent years, there is a strong requirement of low cost, stable microelectro mechanical systems (MEMS) for resonators, microswitches and sensors. Most of these devices consist of freely suspended microcantilevers, which are usually made by the etching of some sacrificial materials. Herein, we have attempted to use Si nanowires, inherited from the parent Si wafer, as a sacrificial material due to its porosity, low cost and ease of fabrication. Prior to the fabrication of the Si nanowires silver nanoparticles were continuously formed on the surface of Si wafer. Vertically aligned Si nanowires were fabricated from the parent Si wafers by aqueous chemical route at $50^{\circ}C$. Afterwards, the morphological and structural characteristics of the Si nanowires were investigated. The morphology of nanowires was strongly modulated by the resistivity of the parent wafer. The 3-step etching of nanowires in diluted KOH solution was carried out at room temperature in order to control the fast etching. A layer of $Si_3N_4$ (300 nm) was used for the selective fabrication of nanowires. Finally, a freely suspended bridge of zinc oxide (ZnO) was fabricated after the removal of nanowires from the parent wafer. At present, we believe that this technique may provide a platform for the inexpensive fabrication of futuristic MEMS.

• Proceedings of the KIEE Conference
• /
• 2002.11a
• /
• pp.79-81
• /
• 2002

ZnO 나노와이어는 ZnO 파우더를 볼밀 처리하여 열증착 방법으로 $1380^{\circ}C$에서 촉매없이 Si 기판위에서 합성되었다. 합성된 ZnO 나노와이어의 길이와 직경은 $20{\sim}30{\mu}m$와 $50{\sim}200$ nm 였다. ZnO 나노와이어 표면을 atomic layer deposition(ALD) 방법으로 $Al_2O_3$ 박막을 얇게 코팅하였다. 성장온도는 $300^{\circ}C$였고, 사용한 전구체는 Trimethlaluminum(TMA)와 distilled water($H_2O$) 이다. Transmission electron microscopy(TEM) 으로 측정한 $Al_2O_3$ 박막의 두께는 40 nm 로서 매우 균일하게 ZnO 나노와이어에 증착되었음을 알 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.422-422
• /
• 2008

본 연구에서, 금 촉매가 4nm 증착된 GaN/$Al_2O_3$ 기판위에 nanowire와 nanowall과 같은 ZnO 나노구조물을 화학기상증착법을 이용하여 합성시켰다. 합성된 ZnO 나노구조물의 형상은 성장시간과 성장온도 조작을 통하여 제어하였다. 합성된 ZnO 나노구조물의 협상을 관찰하기 위해, 전계방출 주사전자현미경을 측정하였다. ZnO 나노구조물은 성장 온도가 $1000^{\circ}C$에서 $1100^{\circ}C$로 증가함에 따라 불균일한 막, nanowire, nanowall 형태로 형상이 점차적으로 변하였으며, 또한 각각의 성장온도에서 성장 시간이 증가함에 따라 나노와이어의 성장이 두드러지게 나타났다. 또한 합성된 ZnO 나노구조물의 결정성과 광학특성을 X-ray diffraction pattern과 상온 photoluminescence spectrum을 이용하여 각각 분석하였다. 이룰 통하여 합성된 ZnO 나노구조물은 wurzite 결정구조를 가지며, 380nm 영역에서 near band edge emission 에 의한 발광 peak와 500~550nm 영역에서 deep level emission에 의한 발광 peak이 나타나는 것을 확인하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.11a
• /
• pp.260-263
• /
• 2004

During the last few years, there have been many efforts on the fabrication of electronic and optical devices based on semiconductor nanowires. Room-temperature ultraviolet lasing in GaN nanowire, ultraviolet light sensing in ZnO nanowire, and dramatically improved hall mobility in Si nanowire have been demonstrated in this article. The studies on semiconductor nanowire based electronic and optical device is reviewed.