• Transactions on Electrical and Electronic Materials
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• 제9권1호
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• pp.24-27
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• 2008

ZnO has intensively attracted interest for the next generation of short wavelength LEDs and semiconductor lasers. However, for the development and application of the devices based on this material, the fabrication of p-type ZnO thin films is pivotal. Generally, the process of preparation of ZnO is unavoidably accompanied by the natural donor ions such as interstitial Zn ions and oxygen vacancy ions that show n-type electrical property and make fabrication of p-type ZnO to be a hard problem. On this study, to realize stable high-quality p-type ZnO thin films, the undoped ZnO thin films were diffused with P in vapor state. The ZnO:P thin films showed high-quality p-type properties electrically and optically.

• 한국진공학회지
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• 제17권1호
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• pp.40-45
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• 2008

유리기판 위에 약 500 nm 의 두께로 성장된 ZnO층의 구조적, 광학적, 전기적 성질에 미치는 갈륨도핑의 영향에 대하여 연구 하였다. 다결정 ZnO 와 GZO 층은 상온에서 radio frequency magnetron sputtering 법을 사용하여 성장되었다. 투과전자현미경 (TEM)과 x-ray 회절분석 (XRD)에 의하면, 갈륨이 도핑된 ZnO 박막의 결정성은 ZnO에 비하여 향상되었고 (002)방향을 따라 우선성장 되었음이 발견되었다. GZO 박막의 투과도는 가시광 영역에서 ZnO 박막에 비해 약 10% 정도 향상된 것으로 나타났다. PL 분석에 따르면, NBE emission 세기와 DL emission 세기의 비는 GZO 와 ZnO의 경우 각각 2.65:1 과 1.27:1로 나타났다. GZO와 ZnO의 비저항은 각각 1.27과 1.61 $\Omega{\cdot}cm$로서 GZO의 전기전도도가 높았다. GZO 와 ZnO의 캐리어농도는 각각 $10^{18}$ and $10^{20}cm^2$/Vs으로 측정되었다. 본 실험결과 따르면, Ga 도핑으로 인해 ZnO 박막의 전기적, 광학적, 구조적 특성이 향상되었음을 알 수 있었다.

• 한국결정성장학회지
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• 제16권1호
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• pp.12-19
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• 2006

Metalorganic chemical vapor deposition (MOCYD) techniques have been applied to fabricate semiconducting ZnO thin films and nanostructures, which are promising for novel optoelectronic device applications using their unique multifunctional properties. The growth and characterization of ZnO thin films on Si and $SiO_2$ substrates by MOCYD as fundamental study to realize ZnO nanostructures was carried out. The precise control of initial nucleation processes was found to be a key issue for realizing high quality epitaxial layers on the substrates. In addition, fabrication and characterization of ZnO nanodots with low-dimensional characteristics have been investigated to establish nanostructure blocks for ZnO-based nanoscale device application. Systematic realization of self- and artificially-controlled ZnO nanodots on $SiO_2/Si$ substrates was proposed and successfully demonstrated utilizing MOCYD in addition with a focused ion beam technique.

• 한국결정성장학회지
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• 제21권5호
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• pp.205-209
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• 2011

ZnO는 반도전성과 초전도성을 나타내며 광학적으로도 독특한 재료로 가스센서, 태양전지, 광학도파관 등 여러 방면에 널리 활용되고 있다. 본 논문에서는 이러한 ZnO에 Al을 첨가함에 따라 광학적 특성에 어떠한 영향을 미치는지 알아보기 위하여 ZnO에 Al 첨가량 변화에 따른 나노구조체를 제작하여 특성을 비교하였다. ZnO 용액은 PVP, ethanol, zinc acetate를 이용하여 Sol의 형태로 제작하였으며, Al첨가용액을 넣어 Al이 첨가된 ZnO Sol을 제작하였다. 제작된 Sol을 전기 방사법을 이용하여 나노구조체를 제조하였다. 제조된 섬유들을 각각 300, 500, $700^{\circ}C$로 열처리 한 후 나노 구조체를 XRD, XPS, SEM을 이용하여 분석하였다. 또한 TGA, DSC를 이용하여 온도변화에 따른 질량 및 열량의 변화를 측정하였다. UVvis를 이용하여 ZnO와 Al이 첨가된 ZnO의 흡광도를 측정 비교하였다.

• 한국전기전자재료학회논문지
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• 제22권11호
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• pp.987-991
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• 2009

We report growth of vertically well-aligned zinc oxide (ZnO) nanorods on indium-tin oxide (ITO)/glass substrates using a simple aqueous solution method at low temperature via control of the ZnO seed layer morphology. ZnO nanoparticles acting as seeds are pre-coated on ITO-coated glass substrates. by spin coating to control distribution and density of the ZnO seed nanoparticles. ZnO nanorods were synthesized on the seed-coated substrates in a dipping process into a main growth solution. It was found that the alignment of ZnO nanorods can be effectively manipulated by the spin-coating speed of the seed layer. A grazing incidence X-ray diffraction pattern shows that the ZnO seed layer prepared using the higher spin-coating speed is of uniform seed distribution and a flat surface, resulting in the vertical growth of ZnO nanorods aligned toward the [0001] direction in the main growth process.

• 한국재료학회지
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• 제22권12호
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• pp.664-668
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• 2012

ZnO nanorods were successfully fabricated on Zn foil by chemical bath deposition (CBD) method. The ZnO precursor concentration and immersion time affected the surface morphologies, structure, and electrical properties of the ZnO nanorods. As the precursor concentration increased, the diameter of the ZnO nanorods increased from ca. 50 nm to ca. 150 nm. The thicknesses of the ZnO nanorods were from ca. $1.98{\mu}m$ to ca. $2.08{\mu}m$. ZnO crystalline phases of (100), (002), and (101) planes of hexagonal wurtzite structure were confirmed by XRD measurement. The fabricated ZnO nanorods showed a photoluminescene property at 380 nm. Especially, the ZnO nanorods deposited for 6 h in solution with a concentration of 0.005M showed a stronger (101) peak than they did (100) or (002) peaks. In addition, these ZnO nanorods showed a good electrical property, with the lowest resistance among the four samples, because the nanorods were densely in contact and relatively without pores. Therefore, a ZnO nanorod substrate is useful as a highly sensitive biochip substrate to detect biomolecules using an electrochemical method.

• 한국재료학회지
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• 제14권5호
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• pp.328-333
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• 2004

Transparent ZnO:Al conductor films for the optoelectronic devices were deposited by using the capacitively coupled DC magnetron sputtering method. The effect of Al doping concentration and discharge power on the electrical and optical properties of the films was studied. The film resistivity of $8.5${\times}$10^{-4}$ $\Omega$-cm was obtained at the discharge power of 40 W with the ZnO target doped with 2 wt% $Al_2$$_O3$. The transmittance of the 840 nm thick film was 91.7% in the visible waves. Increasing doping concentration of 3 wt% $Al_2$$O_3$ in ZnO target results in significant decrease of film resistivity, which may be due to the formation of $Al_2$$O_3$ particles in the as-deposited ZnO:Al film and the reduced ZnO grain sizes. Increasing DC power from 40 to 60 W increases deposition rate by more than 50%, but can induce high defect density in the film, resulting in higher film resistivity.

• 센서학회지
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• 제15권2호
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• pp.84-89
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• 2006

Highly concentrated p-type ZnO thin films can be obtained by doping of N, P and As elements. In this study, undoped ZnO buffer layers were prepared on a (0001) sapphire substrate by a ultra high vaccum pulsed laser deposition(UHV-PLD) method. ZnO buffer layers were deposited with various deposition temperature($400{\sim}700^{\circ}C$) at 350 mtorr of oxygen working pressure. Arsenic doped(1 wt%) ZnO thin films were deposited on the ZnO buffer layers by UHV-PLD. Crystallinity of the samples were evaluated by X-ray diffractometer and scanning electron microscopy. Optical, electrical properties of the ZnO thin films were estimated by photoluminescence(PL) and Hall measurements. The optimal condition of the undoped ZnO buffer layer for the deposition of As-doped ZnO thin films was at $600^{\circ}C$ of deposition temperature.

• 한국전기전자재료학회논문지
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• 제25권2호
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• pp.91-95
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• 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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.429-429
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• 2008

The structural stability and the elastic modulus of hexagonal ZnO nanowires and nanotubes are investigated using atomistic simulations based on the shell model. The ZnO nanowire with (10-10) facets is energetically more stable than that with (11-20). Our calculations indicate that the structural change of ZnO nanowires with (10-10) facets is sensitive to the diameter. With decreasing the diameter of ZnO nanowires, the unit-cell length is increased while the bond-length is reduced due to the change of surface atoms. Unlike the conventional layered nanotubes, the energetic stability of single crystalline ZnO nanotubes is related to the wall thickness. The potential energy of ZnO nanotubes with fixed outer and inner diameters decreases with increasing wall thickness while the nanotubes with same wall thickness are independent of the outer and inner diameters. The transformation of single crystalline ZnO nanotubes with double layer from wurtzite phase to graphitic suggests the possibility of wall-typed ZnO nanotubes. The size-dependent Young's modulus for ZnO nanowires and nanotubes is also calculated. The diameter and the wall thickness play a significant role in the Young's modulus of single crystalline ZnO nanowires and nanotubes, respectively.