• Korean Journal of Materials Research
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• v.22 no.11
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• pp.575-580
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• 2012

The purpose of this study is to investigate the crystalline structure and optical properties of (GaZn)(NO) powders prepared by solid-state reaction between GaOOH and ZnO mixture under $NH_3$ gas flow. While ammoniation of the GaOOH and ZnO mixture successfully produces the single phase of (GaZn)(NO) solid solution within a GaOOH rich composition of under 50 mol% of ZnO content, this process also produces a powder with coexisting (GaZn)(NO) and ZnO in a ZnO rich composition over 50 mol%. The GaOOH in the starting material was phase-transformed to ${\alpha}$-, ${\beta}-Ga_2O_3$ in the $NH_3$ environment; it was then reacted with ZnO to produce $ZnGa_2O_4$. Finally, the exchange reaction between nitrogen and oxygen atoms at the $ZnGa_2O_4$ powder surface forms a (GaZn)(NO) solid solution. Photoluminescence spectra from the (GaZn)(NO) solid solution consisted of oxygen-related red-emission bands and yellow-, green- and blue-emission bands from the Zn acceptor energy levels in the energy bandgap of the (GaZn)(NO) solid solutions.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.95-95
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• 2003

최근, 대면적 평판표시소자 제작을 위한 전기발광 (EL; electroluminescence)소자용 소재로서 GaN 분말을 적용하고자 하는 연구가 진행되고 있다. 이와 같이 GaN 분말을 EL 소재로 사용하기 위해서는 원하는 파장의 빛을 발광할 수 있도록 특정의 불순물을 첨가하여야 할 필요가 있다. Mg이 첨가된 GaN 분말의 합성과 특성에 대한 연구가 있었으며, 희토류 원소가 첨가된 GaN 분말의 특성이 보고된바 있다. 본 논문에서는 GaOOH 분말을 출발물질로 채택하여 Zn가 첨가된 GaN 분말을 합성하고 광학적인 특성을 조사하였다. Zn가 첨가된 GaN 분말을 합성하기 위하여, 우선 CaOOH 분말 1g과 일정량의 ZnO 또는 Zn(NO$_3$)$_3$를 함께 섞어 유발에서 습식 혼합한 후 건조시켰다. Ga에 대한 Zn의 몰 비는 0.1부터 30 까지 변화시켰다. 반응온도는 900~110$0^{\circ}C$의 범위에서 변화시켰고, 반응시간은 1~4시간 범위에서 변화시켰으며, NH$_3$의 유량은 400 sccm으로 하였다. X선 회절분석장치를 사용하여 결정구조를 확인하였고, Zn의 첨가에 따른 광학적 특성은 10 K의 온도에서 광루미네센스(PL; photoluminescence)를 측정하여 평가하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.574-577
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• 2001

GaN thin films on sapphire were grown by rf magnetron sputtering with ZnO buffer layer. The dependence of GaN film quality on ZnO buffer layer was investigated by X-ray diffraction(XRD). The improved film quality has been obtained by using thin ZnO buffer layer. Using Auger electron spectroscopy(AES), it was observed that the annealing process improved the GaN film quality. The surface roughness according to the annealing temperatures(700, 900, 1100$^{\circ}C$) were investigated by AFM(atomic force microscopy) and it was confirmed that the crystallization was improved by increasing the annealing temperature. Photoluminescence at 8K shows a near-band-edge peak at 3.2eV with no deep level emission.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.3
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• pp.242-248
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• 2008

The structural, optical and electrical properties of ZnO films doped with 1.5 at% of 3A materials(B, Al, Ga, In) were studied by sol-gel process. The films were found to be c-axis (002) oriented hexagonal structure on glass substrate, when post heated at 500 $^{\circ}C$. The surface of the films showed a uniform and nano size microstructure and the crystalline size of doped films decreased. The lattice constants of ZnO:B/Al/Ga increased than that of ZnO, while ZnO:In decreased. All the films were highly transparent(above 90 %) in the visible region. The energy gaps of ZnO:B/Al/Ga were increased a little, but that of ZnO:In was not changed. The resistivities of ZnO:Al/Ga/In were less than 0.1 $\Omega$cm. All the films showed a semiconductor properties in the light or temperature, however ZnO:In was less sensitive to it. A figure of merit of ZnO:In had the highest value of 0.025 $\Omega^{-1}$ in all samples.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.23.1-23.1
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• 2009

ZnO is of great interest for various technological applications ranging from optoelectronics to chemical sensors because of its superior emission, electronic, and chemical properties. In addition, vertically well-aligned ZnO nanorods on large areas with good optical and structural properties are of special interest for the fabrication of electronic and optical nanodevices. To date, several approaches have been proposed for the growth of one-dimensional (1D) ZnO nanostructunres. Several groups have been reported the MOCVD growth of ZnO nanorods with no metal catalysts at $400^{\circ}C$, and fabricated a well-aligned ZnO nanorod array on a PLD prepared ZnO film by using a catalyst-free method. It has been suggested that the synthesis of ZnO nanowires using a template-less/surfactant-free aqueous method. However, despite being a well-established and cost-effective method of thin film deposition, the use of magnetrons puttering to grow ZnO nanorods has not been reported yet. Additionally,magnetron sputtering has the dvantage of producing highly oriented ZnO film sat a relatively low process temperature. Currently, more effort has been concentrated on the synthesis of 1D ZnO nanostructures doped with various metal elements (Al, In, Ga, etc.) to obtain nanostructures with high quality,improved emission properties, and high conductance in functional oxide semiconductors. Among these dopants, Ga-doped ZnO has demonstrated substantial advantages over Al-doped ZnO, including greater resistant to oxidation. Since the covalent bond length of Ga-O ($1.92\;{\AA}$) is nearly equal to that of Zn-O ($1.97\;{\AA}$), high electron mobility and low electrical resistivity are also expected in the Ga-doped ZnO. In this article, we report the successful growth of Ga-doped ZnO nanorods on c-Sapphire substrate without metal catalysts by magnetrons puttering and our investigations of their structural, optical, and field emission properties.

• Applied Microscopy
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• v.25 no.3
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• pp.75-81
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• 1995

The microstructural characterization of ternary $ZnS_{x}Se_{1-x}$(x=0.085) on GaAs(001) substrate grown up to $2{\mu}m\;at\;300^{\circ}C$ by molecular beam epitaxy(MBE) which has a single growth chamber was investigated by high resolution transmission electron microscope (HRTEM) working at 300 kV with point resolution of 0.18nm. The interface in the ZnSSe/GaAs specimen maintains a pseudomorphism with the substrate, but the epilayer has high density of stacking faults and moire fringes. The pits which had formed along <111> direction were found at the interface of ZnSSe/GaAs. The pits were responsible for producing defects in both epilayer and substrate. The wavy interface which has the difference of 15nm in height was found to maintain the pseudomorphism with the substrate and no stacking faults were found around the interface. However there exists faint and fine moire fringes in the epilayer near interface.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.6
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• pp.499-502
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• 2008

In this work, Ga-doped ZnO (GZO) thin films for gas sensor application were deposited on low temperature co-fired ceramics (LTCC) substrates, by RF magnetron sputtering method. The LTCC substrate is one of promising materials for this application since it has many advantages (e.g., low cost production, high manufacturing yields and easy realizing 3D structure etc.). The LTCC substrates with thickness of $400\;{\mu}m$ were fabricated by laminating 12 green tapes which consist of alumina and glass particle in an organic binder. The structural properties of the fabricated GZO thin film with thickness of 50 nm is analyzed by X-ray diffraction method (XRD) and field emission scanning electron microscope (FESEM). The film shows good adhesion to the substrate. The GZO gas sensors are tested by gas measurement system and show fast response and recovery characteristics to $NO_x$ gas that is 27.2 and 27.9 sec, recpectively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.6
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• pp.302-308
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• 2013

In this study, we report the synthesis and characteristics of gallium oxide ($Ga_2O_3$) nanoparticles prepared by the polymerized complex method. $Ga_2O_3$ nanoparticles were synthesized using $Ga(NO_3)_3$, ethylene glycol, and citric acid as the starting materials at a low temperature of $500{\sim}800^{\circ}C$. The temperature of the weight reduction by the loss of organic precursor was revealed using TG-DTA analysis. The crystal structural change of $Ga_2O_3$ nanoparticles by the annealing process was investigated by XRD analysis. The morphologies and the size distributions of $Ga_2O_3$ nanoparticles were analyzed using SEM.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.1
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• pp.8-14
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• 2014

In this study, we investigated synthesis and characteristics of gallium oxide ($Ga_2O_3$) powders prepared by precipitation method. $Ga_2O_3$ powders were synthesized using $Ga(NO_3)_3$ as a starting material and $NH_4OH$ as a precipitant. The oxidation temperature of $Ga(OH)_3$ and phase transition temperature of $Ga_2O_3$ was revealed using TG-DSC analysis. The crystal structural change of $Ga_2O_3$ powders was investigated by XRD analysis. The morphologies and size distributions of $Ga_2O_3$ particles were analyzed using SEM.

• Current Photovoltaic Research
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• v.3 no.2
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• pp.54-60
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• 2015

ZnSnO thin films were deposited by atomic layer deposition (ALD) process using diethyl zinc ($Zn(C_2H_5)_2$) and tetrakis (dimethylamino) tin ($Sn(C_2H_6N)_4$) as metal precursors and water vapor as a reactant. ALD process has several advantages over other deposition methods such as precise thickness control, good conformality, and good uniformity for large area. The composition of ZnSnO thin films was controlled by varying the ratio of ZnO and $SnO_2$ ALD cycles. The ALD ZnSnO film was an amorphous state. The band gap of ZnSnO thin films increased as the Sn content increased. The CIGS solar cell using ZnSnO buffer layer showed about 18% energy conversion efficiency. With such a high efficiency with the ALD ZnSnO buffer and no light soaking effect, AlD ZnSnO buffer mighty be a good candidate to replace Zn(S,O) buffer in CIGSsolar cells.