• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.10
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• pp.620-624
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• 2015

We have studied structural, optical and electrical properties of In-Ga-doped ZnO (IGZO) thin films. The IGZO thin films were deposited on the corning 1737 glass by RF magnetron sputtering method. The RF power in sputtering process was varied as 30, 50, 70, and 90 W respectively. All of the IGZO thin films transmittance in the visible range (400 nm ~ 800 nm) was above 83%. XRD analysis showed the IGZO thin films amorphous structure of the thin films without any peak. And also IGZO thin film have low resistivity ($1.99{\times}10^{-3}{\Omega}cm$), high carrier concentration ($6.4{\times}10^{20}cm^{-3}$), and mobility ($10.3cm^2V^{-1}s^{-1}$). By the studies we found that IGZO transparent thin film can be used as optoelectronic material and introduced application possibility for future electronic devices.

• Journal of Powder Materials
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• v.24 no.2
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• pp.108-114
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• 2017

We fabricate fine (<$20{\mu}m$) powders of $Bi_{0.5}Sb_{1.5}Te_3$ alloys using a large-scale production method and subsequently consolidate them at temperatures of 573, 623, and 673 K using a spark plasma sintering process. The microstructure, mechanical properties, and thermoelectric properties are investigated for each sintering temperature. The microstructural features of both the powders and bulks are characterized by scanning electron microscopy, and the crystal structures are analyzed by X-ray diffraction analysis. The grain size increases with increasing sintering temperature from 573 to 673 K. In addition, the mechanical properties increase significantly with decreasing sintering temperature owing to an increase in grain boundaries. The results indicate that the electrical conductivity and Seebeck coefficient ($217{\mu}V/K$) of the sample sintered at 673 K increase simultaneously owing to decreased carrier concentration and increased mobility. As a result, a high ZT value of 0.92 at 300 K is achieved. According to the results, a sintering temperature of 673 K is preferable for consolidation of fine (<$20{\mu}m$) powders.

• Journal of the Semiconductor & Display Technology
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• v.9 no.4
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• pp.77-81
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• 2010

The AZO thin films were deposited on the corning 1737 glass plate by the RF magnetron sputtering and effects of working pressure and oxygen contents on the electrical properties were investigated. XRD spectra showed a preferred orientation along the c-axis and a minimum FWHM for the 70mTorr. From the surface analysis (AFM), the number of crystal grain of AZO thin film increased as working pressure increased. The film deposited with 70mTorr of working pressure showed n-type semiconductor characteristic having suitable resistivity $-1.59{\times}10^{-2}{\Omega}cm$, carrier concentration $-10.1{\times}10^{19}cm^{-3}$, and mobility $-4.35cm^2V^{-1}s^{-1}$ while other films by 7 mTorr, 20 mTorr of working pressure closed to metallic films. The films including the oxygen represent stoichiometric composition similar to the oxide. The transmittance of the film was over 85% in the visible light range regardless of the changes in working pressure and oxygen contents.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.803-805
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• 1992

The InP single crystals were grown by Modified Synthesis Solute Diffusion (SSD) method and its properties were investigated. The crystal growth rate and lattice constant $a_{\circ}$ of the grown crystals were 1.8mm/day, 5.867${\AA}$ respectively. Etch pits density along growth direction of crystal had nearly uniformity' about (2-6)x10 $cm^{-2}$ from first freeze part to last freeze part. The carrier concentration, mobility and resistivity varied from 6.25 x $10^{15}cm^{-3}$, 4218 $cm^{2}$/V sec and 1.38 x $10^{-1}{\Omega}^{-cm}$ at the first freeze part to 8.8x$10^{-3}cm^{-3}$, 4012 $cm^{2}$/V.sec and 1.43 X $10^{-1}{\Omega}^{-cm}$ at the last freeze part. In the photoluminescence at 10K, the radiation transitions were observed by the near band edge recombination, D-A pair recombination and its phonon replica in the undoped InP.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.12
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• pp.794-799
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• 2017

Ga-doped ZnO (GZO) films were deposited by an RF magnetron sputtering method on glass substrates using ZnO as a target containing 5 wt% $Ga_2O_3$ powder (for Ga doping). The structural, electrical, and optical properties of the GZO thin films were investigated as a function of the substrate temperatures. The deposition rate decreased with increasing substrate temperatures from room temperature to $350^{\circ}C$. The films showed typical orientation with the c-axis vertical to the glass substrates and the grain size increased up to a substrate temperature of $300^{\circ}C$ but decreased beyond $350^{\circ}C$. The resistivity of GZO thin films deposited at the substrate temperature of $300^{\circ}C$ was $7{\times}10^{-4}{\Omega}cm$, and it showed a dependence on the carrier concentration and mobility. The optical transmittances of the films with thickness of $3,000{\AA}$ were above 80% in the visible region, regardless of the substrate temperatures.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.3
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• pp.222-226
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• 2008

With different seed adhesion methods, we obtained two different aspects with or without micro-bubble in the interface between a seed and a dense graphite seed holder. To improve the quality of SiC wafer, we introduced a sucrose caramelizing step at the seed adhesion using the sucrose, The n-type 2 inch single crystal exhibiting the polytype of 6H-SiC were successfully fabricated and carrier concentration levels of about $10^{16}/cm^3$ was determined from Hall measurements, As compared to the characteristics of SiC crystal grown with micro-bubble in the interface between the seed and the dense graphite seed holder, the SiC crystal grown without micro-bubble definitely exhibited lower resistivity, lower micropipe density and higher mobility relatively.

• Korean Journal of Metals and Materials
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• v.47 no.1
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• pp.38-43
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• 2009

To investigate the effect of RF power on the structural, optical and electrical properties of amorphous InGaZnO (a-IGZO), its thin films and TFTs were prepared by RF magnetron sputtering method with different RF power conditions of 40, 80 and 120 W at room temperature. In this study, as RF power during the deposition process increases, the RMS roughness of a-IGZO films increased from 0.26 nm to 1.09 nm, while the optical band-gap decreased from 3.28 eV to 3.04 eV. In the case of the electrical characteristics of a-IGZO TFTs, the saturation mobility increased from $7.3cm^2/Vs$ to $17.0cm^2/Vs$, but the threshold voltage decreased from 5.9 V to 3.9 V with increasing RF power. It is regarded that the increment of RF power increases the carrier concentration of the a-IGZO semiconductor layer due to the higher generation of oxygen vacancies.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.319-320
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• 2009

In this study, high-quality Al-N doped p-type ZnO thin films were deposited on n-type Si (100) wafer or Si coated with buffer layer by DC magnetron sputtering in the mixture of $N_2$ and $O_2$ gas. The target was ceramic ZnO mixed with $Al_2O_3$ (2 wt%). The p-type ZnO thin film showed higher carrier concentration $2.93\times10^{17}cm^{-3}$, lower resistivity of $5.349\;{\Omega}cm$ and mobility of $3.99\;cm^2V^{-1}S^{-1}$, respectively. According to PL spectrum, the Al donor energy level depth ($E_d$) of Al-N codoped p-type ZnO film was reduced to about 51 meV, and the N acceptor energy level depth ($E_a$) was reduced to 63 meV, respectively.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.168-171
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• 1988

The p-n homo junction diode of the III-V ternary alloy semiconductor $In_{1-x}Ga_xP$ : S grown by the temperature gradient solution (TGS) was fabricated by Zn-diffusion, and it's characteristics was investigated. The carrier concentration of $In_{1-x}Ga_xP$ doped with sulfur, 0.5 mol %, was $1{\times}10^{17}cm^{-3}$ and the mobility was varied with the composition. In the case that the diffusion time was constant as 30 minutes. The temperature dependence of diffusion coefficient was decreased from D= $4.2{\times}10^{-5}$ exp (-1.74/$k_{B}T$) to D= $2.5{\times}10^{-5}$ exp (-3.272/$k_{B}T$) with increasing of composition $\times$ from 0.43 to 0.98. The major peak of E.L spectrum was due to D-A pair recombination and the peak intensity was increased with the increasing of input current. And the E.L intensity was decreased with the increasing temperature, and shift to the long wavelength. The luminescence efficiencies measured at $5^{\circ}C$, atmosphere temperature, was decreased from $2.6{\times}10^{-4}$% to $9.49{\times}10^{-6}$ % with increasing of composition it from 0.39, direct transition region, to 0.98, indirect transition region.

• Korean Journal of Crystallography
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• v.12 no.3
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• pp.171-176
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• 2001

HgCdTe films were grown on the (100). (111), (211) CdZnTe, and (100) GaAs substrates by metal organic chemical vapor epitaxy. We have investigated the surface morphology, electrical properties, crystalline qualities, and composition of HgCdTe with substrates orientation. Three dimensional facet growth was occurred on (111) CdZnTe substrate. The crystalline quality of HgCdTe on (100) CdZnTe was superior to that of HgCdTe on (100) GaAs. FWHM values of double crystal x-ray diffraction of HgCdTe on (100) CdZnTe and (100) GaAs were 55 and 125arcsec, respectively. HgCdTe on GaAs substrate showed n-type conductivity with high mobility, however, HgCdTe on CdZnTe showed p-type conductivity with carrier concentration of higher than 10/sup 16/㎤.