• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.121-122
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• 2007

Single crystal $CuAlSe_2$ layers were grown on thoroughly etched sem-insulating GaAs(l00) substrate at $410^{\circ}C$ with hot wall epitaxy (HWE) system by evaporating $CuAlSe_2$ source at $680^{\circ}C$. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of single crystal $CuAlSe_2$ thin films measured with Hall effect by van der Pauw method are $9.24{\times}l0^{16}\;cm^{-3}$ and $295\;cm^2/V{\cdot}s$ at 293K, respectively. The temperature dependence of the energy band gap of the $CuAlSe_2$ obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;2.8382\;eV\;-\;(8.68\;{\times}\;10^{-4}\;eV/K)T^2/(T\;+\;155\;K)$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.263-266
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• 2004

The stochiometric mix of evaporating materials for the $ZnGa_2Se_4$ single crystal thin films were prepared from horizental furnace. The polycrystal structure obtaind from the power x-ray diffraction was defect chalcopyrite. The lattice costants $a_0\;and\;c_0\;were\;a_0=5.51\;A,\;c_0=10.98\;A$. To obtains the single crystal thin films, $ZnGa_2Se_4$ mixed crystal were deposited on throughly etched Si(100) by the Hot Wall Epitaxy (HWE) system. The temperates of the source and the substrate were $590^{\circ}C\;and\;450^{\circ}C$, respectively. The crystalline structure of single crystal thin films was investigated by the double crystal X-ray diffraction(DCXD). Hall effect on this sample was measured by the method of van der Pauw and studied on carrier density and mobility dependence on temperature. In order to explore the applicability as a photoconductive cell, we measured the sensitivity($\gamma$), the ratio of photocurrent to dark current(pc/dc), maximum allowable rower dissipation(MAPD), spectral response and response time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.381-384
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• 2004

The stochiometric nix of evaporating materials for the $AgInS_2$ single crystal thin films were prepared from horizontal furnace. The polycrystal structure obtaind from the power x-ray diffraction was chalcopyrite. The lattice costants $a_0\;and\;c_0$ were $a_0=5.86(5.82)\;A,\;c_0=11.355(11.17)\;A$. To obtains the single crystal thin films, $AgInS_2$ mixed crystal were deposited on throughly etched GaAs(100) by the Hot Wall Epitaxy(HWE) system. The temperates of the source and the substrate were $590^{\circ}C\;and\;450^{\circ}C$, respectively. The crystalline structure of single crystal thin films was investigated by the double crystal X-ray diffraction(DCXD). Hall effect on this sample was measured by the method of van der Pauw and studied on carrier density and mobility dependence on temperature. In order to explore the applicability as a photoconductive cell, we measured the sensitivity($\gamma$), the ratio of photocurrent to dark current (pc/dc), maximum allowable power dissipation(MAPD), spectral response and response time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.160-162
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• 2003

ZnO epilayer were synthesized by the pulesd laser deposition(PLD) process on $Al_2O_3$ substrate after irradiating the surface of the ZnO sintered pellet by the ArF(193nm) excimer laser. The substrate temperatures was $400^{\circ}C$. The crystalline structure of epilayer was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of ZnO epilayer measured with Hall effect by van der Pauw method are $8.27{\times}10^{16}\;cm^{-3}\;and\;299\;cm^2V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the ZnO obtained from the absorption spectra was well described by the Varshni's relation, $E_g(T)\;=\;3.3973\;eV\;-\;(2.69{\times}10^{-4}\;eV/K)T^2/(T\;+\;463K)$. After the as-grown ZnO epilayer was annealed in Zn atmospheres, oxygen and vaccum the origin of point defects of ZnO atmospheres has been investigated by the photoluminescence(PL) at 10 K. The native defects of $V_{Zn}$, Vo, $Zn_{int}$, and $O_{int}$ obtained by PL measurements were classified as a donors or accepters type.

• Korean Journal of Crystallography
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• v.12 no.3
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• pp.127-136
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• 2001

A stoichiometric mixture of evaporating materials for ZnGa₂Se₄single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, ZnGa₂Se₄mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were 610℃ and 450℃, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of ZnGa₂Se₄single crystal thin films measured from Hall effect by von der Pauw method are 9.63×10/sup 17/㎤ and 296 ㎠/V·s at 293 K, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c-axis of the ZnGa₂Se₄single crystal thin film, we have found that the values of spin orbit splitting △so and the crystal field splitting Δcr were 251.9meV and 183.2 meV at 10 K, respectively. From the photoluminescence measurement on th ZnGa₂Se₄single crystal thin film, we observed free excition (Ex) existing only high quality crystal and neutral bound exiciton (A°, X) having very strong peak intensity. Then, the full-width-at-half-maximum (FWHM) and binding energy of neutral acceptor bound excition were 11 meV and 24.4 meV, respectivity. By Haynes rule, an activation energy of impurity was 122 meV.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.6
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• pp.542-546
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• 1999

InP single crystal, III-V binary compound semiconductor, was grown by VGF(vertical gradient freeze) method using quartz ampoule and its electrical optical properties were investigated. Phosphorous powders were put in the bottom of quartz ampoule and Indium metal charged in conical quartz crucible what was attached at the upper side position inside the quartz ampoule. It was vacuous under the pressure of $10^5$Torr and sealed up. Indium metal was melted at $1070^{\circ}C$ and InP composition was formed by diffusion of phosphorous sublimated at $450^{\circ}C$ into Indium melt. By cooling the InP composition melt ($2^{\circ}C$~$5^{\circ}C$/hr of cooling rate) in range of $1070^{\circ}C$~$900^{\circ}C$, InP crystal was grown. The grown InP single crystals were investigated by X-ray analysis and polarized optical microscopy. Electrical properties were measured by Van der Pauw method. At the cooling method. At the cooling rate of $2^{\circ}C$/hr, growth direction of ingot was [111] and the quality of ingot was better at the upper side of ingot than the lower side. It was found that the InP crystals were n-type semiconductor and the carrier concentration, electron mobility and relative resistivity were $10^{15}$~$10^{16}/\textrm{cm}^3$ , $2\times 10^3$~$3\times 10^4{\textrm}{cm}^2$/Vsec and$2\times 10^{-1}$~$2\times 10^{-3}$/ Wcm in the range of 150K~300K, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.212-212
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• 2009

Thermoelectric devices were used to wide range of application. At present, increasing the efficiency of these devices, in particular, through the preparation of materials showing a high thermoelectric figure of merit, Z, $Bi_2Te_3$ and $Sb_2Te_3$ thin films on Si substrates are deposited by flash evaporation method for thermopile sensor applications. In order to enhance the thermoelectric properties of the thin film, annealing in high vacuum is carried out in the temperature range from 200 to $350^{\circ}C$. The microstructure of the film is investigated by XRD and SEM. The resistivity and Seebeck coefficient of the films are measured by Van der Pauw method and hot probe method respectively. At elevating annealing temperature, the crystallinity and thermoelectrical properties of films are improved by increasing the size of grains. At excessive high annealing temperatures, it is shown that Seebeck coefficient of films is decreased because of Te evaporation. By optimizing the annealing conditions, it is possible to obtain a high performance thin film with a thermoelectric properties.

• Electrical & Electronic Materials
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• v.10 no.3
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• pp.226-232
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• 1997

Ternary semiconductor $Al_{x}$G $a_{1-x}$ Sb crystals which have energy gap of 0.7eV-1.6 eV at room temperature according to the composition ratios were grown by the vertical Bridgman method. The characteristics of the crystals were investigated by XRD, HRTEM and Hall effect. The lattice constants of $Al_{x}$G $a_{1-x}$ Sb crystals were varied from 6.096A over .deg. to 6.135A over .deg. with the composition ratio x. The Hall effect of the $Al_{x}$G $a_{1-x}$ Sb crystals were measured by van der Pauw method with the magnetic field of 3 kilogauss at room temperature. The resistivities of Te-doped $Al_{x}$G $a_{1-x}$ Sb crystals were increased from 0.071 to 5 .OMEGA.-cm at room temperature according to the increment of the composition ratio x. The mobilies of $Al_{x}$G $a_{1-x}$ Sb crystals varied with the composition ratio x resulted in the following three different regions of GaSb-like (0.leq.x.leq.0.3), intermediate (0.3.leq.x.leq.0.4) and AlSb-like (0.4.leq.x.leq.l).q.l).q.l).q.l).

• Korean Journal of Crystallography
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• v.7 no.1
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• pp.81-87
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• 1996

The mechanism of silicon incorporation has been analyzed for the boat-grown GaAs crystals on the basis of phase equilibrium in the Ga and As system. Comparison was made between silicon concentrations calculated from the thermodynamics of incorporation reaction and carrier concentrations measured from van der Pauw method. For the 1-T HB(single temperature zone horizontal Bridgman) crystals, calculated concentrations were 5.3 ×10 15 (atoms/cm3), measured as 9.8 ×10 15(/cm3) at the seed part. They were calculated to be 1.1 ×10 16(atoms/cm3) and measured as 1.5 ×10 16(/cm3) for the 2-T(double temperature zone) HB crystals. On the other hand, it was found to be closer between the calculated and measured silicon concentrations for the VGF(vertical gradient freeze) crystals, which were grown within half the run time compared with 1-T or 2-T HB method.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.11a
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• pp.68-68
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• 2001

Thin films of polycrystalline silicon (poly-Si) is a promising material for use in large-area electronic devices. Especially, the poly-Si can be used in high resolution and integrated active-matrix liquid-crystal displays (AMLCDs) and active matrix organic light-emitting diodes (AMOLEDs) because of its high mobility compared to hydrogenated _amorphous silicon (a-Si:H). A number of techniques have been proposed during the past several years to achieve poly-Si on large-area glass substrate. However, the conventional method for fabrication of poly-Si could not apply for glass instead of wafer or quartz substrate. Because the conventional method, low pressure chemical vapor deposition (LPCVD) has a high deposition temperature ($600^{\circ}C-1000^{\circ}C$) and solid phase crystallization (SPC) has a high annealing temperature ($600^{\circ}C-700^{\circ}C$). And also these are required time-consuming processes, which are too long to prevent the thermal damage of corning glass such as bending and fracture. The deposition of silicon thin films on low-cost foreign substrates has recently become a major objective in the search for processes having energy consumption and reaching a better cost evaluation. Hence, combining inexpensive deposition techniques with the growth of crystalline silicon seems to be a straightforward way of ensuring reduced production costs of large-area electronic devices. We have deposited crystalline poly-Si thin films on soda -lime glass and SiOz glass substrate as deposited by PVD at low substrate temperature using high power, magnetron sputtering method. The epitaxial orientation, microstructual characteristics and surface properties of the films were analyzed by TEM, XRD, and AFM. For the electrical characterization of these films, its properties were obtained from the Hall effect measurement by the Van der Pauw measurement.