• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.533-538
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• 2001

The ZnSe sample grown by chemical bath deposition (CBD) method were annealed in Ar gas at 450$^{\circ}C$ Using extrapolation method of X-ray diffraction pattern, it was found to have zinc blend structure whose lattice parameter a$\_$o/ was 5.6687 ${\AA}$. From Hall effect, the mobility was likely to be decreased by impurity scattering at temperature range from 10 K to 150 K and by lattice scattering at temperature range from 150 K to 29 3K. The band gap given by the transmission edge changed from 2.7005 eV at 293 K to 2.8739 eV at 10 K. Comparing photocurrent peak position with transmission edge, we could find that photocurrent peaks due to excition electrons from valence band, $\Gamma$$\_$8/ and $\Gamma$$\_$7/ to conduction band $\Gamma$$\_$6/ were observed at photocurrent spectrum. From the photocurrent spectra by illumination of polarized light on the ZnSe thin film, we have found that values of spin orbit coupling splitting Δso is 0.0981 eV. From the PL spectra at 10 K, the peaks corresponding to free bound excitons and D-A pair and a broad emission band due to SA is identified. The binding energy of the free excitons are determined to be 0.0612 eV and the dissipation energy of the donor -bound exciton and acceptor-bound exciton to be 0.0172 eV, 0.0310 eV, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.216-217
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• 2008

Zinc-oxide films were deposited by pulsed laser deposition (PLD) technique using doped ZnO target (mixed $In_2O_3$ 0.1, 0.3, 0.6 at. % - atomic percentage) on the p-type Si(111) substrate. A little Indium has added at the n-ZnO films for the electron concentration control and enhanced the electrical properties. Also, post thermal annealed ZnO films are shown an enhanced structural and controled electron concentration by the annealing condition for the hetero junction diode of a better emitting characteristics. The electrical and the diode characteristics of the ZnO films were investigated by using Hall effect measurement and current-voltage measurement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1375-1381
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• 2007

In this paper, we propose a linear modeling and identical PD controller design scheme for the three-pole hybrid-type AMB recently developed in the laboratory, which consists of three permanent magnets, providing bias flux, three Hall diodes, measuring rotor displacements, and ring type permanent magnet bearing, stabilizing in axial and tilting directions. Along the three physical coordinates formed by three poles, we introduce the redundant coordinate system and three identical decoupled controllers to construct linear model. The experiments are also carried out in order to verify the effectiveness of proposed controller in stabilizing the transient and steady state response of rotor.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제22권1호
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• pp.81-85
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• 2009

We has been analysed optical properties of OLED(organic light emitting diode) and characteristics of ITO(Indium Tin Oxide) in terms of $O_2$ plasma treatment for manufacturing high efficiency OLED, RF power of $O_2$ plasma was changed 25, 50, 100, 200 W. $O_2$ gas flow, gas pressure and treatment time were fixed. Sheet resistance and surface roughness of ITO were measured by Hall-effect measurement system and AFM, respectively. The ranges of sheet resistance and surface roughness were $5.5{\sim}6,06\;{\Omega}$ and $2.438{\sim}3.506\;nm$ changing of RF power, respectively, PM(Passive Matrix)OLED was fabricated with the structure of ITO(plasm treatment)/TPD($400\;{\AA}$)/$Alq_3(600\;{\AA})$/LiF($5\;{\AA}$)/Al($1200\;{\AA}$). Turn-on voltage of PMOLED was 7 V and luminance was $7,371\;cd/m^2$ at the RF power of 25 W, $O_2$ plasma treatment of ITO surface was result in lowering the operating voltage and improving luminance of PMOLED.

• Journal of IKEEE
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• 제28권1호
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• pp.104-109
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• 2024

In this research, we explored the influence of post-annealing atmospheres on the electrical properties of Ga₂O₃/SiC heterojunction diodes. We fabricated Ga₂O₃/SiC heterojunction diodes by RF sputtering and after the fabrication the post-annealing in various gas atmospheres was performed. We measured the changes in deep-level defects using Deep Level Transient Spectroscopy (DLTS) and we conducted an electrical characteristic of J-V measurement and Hall measurement to analyzed the effects of annealing atmosphere on Ga₂O₃/SiC heterojunction diode. In the N₂ annealed devices, the highest on-state current was measured as 3.06 × 10^-2 A/cm^2, and an increase in carrier concentration of 3.8 × 10¹⁴ cm^-3 was observed. This confirms that the variations in deep level defects due to the post-annealing atmosphere can influence the electrical properties.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제22권5호
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• pp.419-424
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• 2009

ZnO films doped with different contents of indium ($0.1{\sim}10$ at.%) were deposited on Si (111) substrate by Pulsed Laser Deposition (PLD). The structural, electrical and optical properties of the films were investigated using XRD, AFM, Hall and PL measurement. Results showed that un-doped ZnO film had (002) plane as the c-axis orientated growth, whereas indium doped ZnO films exhibited the peak of (002) and the weak (101) plane. In addition, in the indium doped ZnO films, the electron concentration is ten times higher than that of un-doped ZnO film, while the resistivity is ten times lower than that of un-doped ZnO film. The indium doped ZnO films have UV emission about 380 nm and show a red shift with increasing contents of indium. The I-V curve of the fabricated diode show the typical diode characteristics and have the turn on voltage of about 2 V.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제18권11호
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• pp.1056-1060
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• 2005

We investigated the fabrication and characteristics of the nitride-based spin-polarized LEDs with room-temperature ferromagnetic (Ga,Mn)N layer as a spin injection source. The (Ga,Mn)N thin films having room-temperature ferromagnetic ordering were found to exhibit the negative MR and anomalous Hall resistance up to room temperature, revealing the existence of spin-polarized electrons in (Ga,Mn)N films at room temperature. The electrical characteristics in the spin LEDs did not degraded in spite of the insertion of the (Ga,Mn)N layer into the LED structure. In EL spectra of the spin LEDs, it is confirmed that the devices produce intense EL emission at 7 K as well as room temperature. These results are expected to open up new opportunities to realize room-temperature operating semiconductor spintronic devices.

• Journal of the Korean Crystal Growth and Crystal Technology
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• 제9권1호
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• pp.39-42
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• 1999

Nitrogen-doped SiC(3C) (N-SiC(3C)) epliayers were grown on Si(111) substrate at $1250^{\circ}C$ using chemical vapor deposition (CVD) technique by pyrolyzing tetramethylsilane(TMS) in $H_{2}$ carrier gas. SiC(3C) layer was doped using $NH_{3}$ during the CVD growth to be n-type conduction. Physical properties of N-SiC(3C) were investigated by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) patterns, Raman spectroscopy, cross-sectional transmission electron microscopy (XTEM), Hall measurement, and current-voltage(I-V) characteristcs of the N-SiC(3C)/Si(p) diode. N-SiC(3C) layers exhibited n-type conductivity. The n-type doping of SiC(3C) could be controlled by nitrogen dopant using $NH_{3}$ at low temperature.

• Journal of the Korean Vacuum Society
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• 제18권5호
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• pp.384-389
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• 2009

ZnO, a wurtzite lattice structure, has attracted much attention as a promising material for light-emitting diodes (LEDs) due to highly efficient UV emission resulting from its large band gap of 3.37 eV, large exciton binding energy of 60 meV, and low power threshold for optical pumping at room temperature. For the realization of LEDs, both n-type ZnO and p-type ZnO are required. Now, n-type ZnO for practical applications is available; however, p-type ZnO still has many drawbacks. In this study, ZnO films were grown on glass substrates by using atomic layer deposition (ALD) and the ZnO films were irradiated by nitrogen ion beams (20 keV, $10^{13}{\sim}10^{15}ions/cm^2$). The effects of nitrogen-beam irradiation on the ZnO structure as well as the electrical property were investigated by using fieldemission scanning electron microscopy (FESEM) and Hall-effect measurement.

• Journal of IKEEE
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• 제26권1호
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• pp.50-55
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• 2022

SiC is a power semiconductor with a wide bandgap, high insulation failure strength, and thermal conductivity, but many deep-level defects. Defects that appear in SiC can be divided into two categories, defects that appear in physical properties and interface traps that appear at interfaces. In this paper, Z_1/2 trap concentration 0 ~ 9×10¹⁴ cm^-3 reported at room temperature (300 K) is applied to SiC substrates and epi layer to investigate turn-on characteristics. As the trap concentration increased, the current density, Shockley-read-Hall (SRH), and Auger recombination decreased, and Ron increased by about 550% from 0.004 to 0.022 mohm.