• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.2
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• pp.155-160
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• 2020

Ga₂O₃/n-type 4H-SiC heterojunction diodes were fabricated by RF magnetron sputtering. The optical properties of Ga₂O₃ and electrical properties of diodes were investigated. I-V characteristics were compared with simulation data from the Atlas software. The band gap of Ga₂O₃ was changed from 5.01 eV to 4.88 eV through oxygen annealing. The doping concentration of Ga₂O₃ was extracted from C-V characteristics. The annealed oxygen exhibited twice higher doping concentration. The annealed diodes showed improved turn-on voltage (0.99 V) and lower leakage current (3 pA). Furthermore, the oxygen-annealed diodes exhibited a temperature cross-point when temperature increased, and its ideality factor was lower than that of as-grown diodes.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.4
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• pp.121-128
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• 1996

The impact ionization rate of thethighly-doped AlGaAs/GaAs quantum well structure is calculated, which is an important parameter ot design theinfrared detector APD and the novel neural device. In conjunction with ensemble monte carlo method and quantum mechanical treatment, we analyze the effects of the parameters of quantum well structure on the impact ionization rate. Since the number of the occupied subbands increases while the energy of the subbands decreases as the width of quantum well increases, the impact ionization rate increases in the range of th esmall well width but gradually the increament slows down and is finally saturated. Due to the effect of the energy of the injected electrons into the quantum well and the tunneling through the barrier, the impact ionization rate increases for the range of the small barrier width and decreases for the range of the large barrier width. Thus, there exists a barrier width to maximize the impact ionzation rate for a mole fraction x, and the barrier width moves to the larger vaue as the mole fraction x increases. The impact ionization rate is much more sensitive to the variation of the doping density than that of the other quantum well parameters. We found that there is a limit of the doping density to confine the electronics in the quantum well effectively.

• Transactions on Electrical and Electronic Materials
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• v.2 no.4
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• pp.24-29
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• 2001

GaN films were grown for various Mg doping concentrations in metal-organic chemical vapor deposition. Below the Mg concentration of 10$^{19}$ ㎤, the thermally annealed sample shows the compensated phase to n-type GaN in Hall measurement. In the MB concentration of 4$\times$10$^{19}$ ㎤ corresponding to the hole carrier concentration of 2.6$\times$1$^{19}$ ㎤ there exists a photoluminescence center of the donor and the acceptor pair transition of the 3.28-eV band. This center is correlated with the defects for a shallow donor of the $V_{Ga}$ and for an acceptor of $Mg_{Ga}$ . The acceptor level shows the binding energy of 0.2-0.25 eV, which was observed by the photon energy of the photocurrent signal of 3.02-3.31 eV. Above the Mg concentration of 4$\times$10$^{19}$ ㎤, both the Mg doping level and Mg concentration were saturated and there Is a photoluminescence center of a deep donor and an acceptor pair transition of the 2.76-eV blue band.

• Journal of Magnetics
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• v.18 no.3
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• pp.240-244
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• 2013

The influences of Gallium doping on the magnetic microstructures and corrosion behaviors of Nd-Fe-B-Ti-C alloys are investigated. The cooling rate for obtaining fully amorphous structure is raised, and the glassforming ability is improved by the Ga addition. The High Resolution Transmission Electron Microscopy image shows that the ${\alpha}$-Fe and $Fe_3B$ soft magnetic phases become granular surrounded by the $Nd_2Fe_{14}B$ hard magnetic phase. The rms and $({\Delta}{\varphi})_{rms}$ value of Nd-Fe-B-Ti-C nanocomposite alloy thick ribbons in the typical topographic and magnetic force images detected by Magnetic Force Microscopy(MFM) decreases with 0.5 at% Ga addition. The corrosion resistances of $Nd_9Fe_{73}B_{12.6}C_{1.4}Ti_{4-x}Ga_x$ (x = 0, 0.5, 1) alloys are enhanced by the Ga addition. It can be attributed to the formation of more amorphous phases in the Ga doped samples.

• Korean Journal of Materials Research
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• v.8 no.6
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• pp.526-531
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• 1998

A hydride vapor phase epitaxy (HVPE) method was performed to grow the $10~240\mu{m}$ thick GaN films on (111) spinel $MgAl_2O_4$ substrate. The GaN films on $MgAl_2O_4$ substrate revealed a photoluminescence (PL) characteristics of the impurity doped GaN by the out-diffusion and auto-doping of Mg from $MgAl_2O_4$ substrate during GaN growth. The PL spectrum measured at 10K consists of free and bound excitons related recombination transitions and impurity-related donor-acceptor pair recombination and its phonon replicas. However, the deep-level related yellow band emission was not observed. The peak energy of neutral donor bound excitonic emission and the frequency of Raman $E_2$ mode were exponentially decreased with increasing the GaN thicknesses. and the frequency of E, Raman mode was shifted with the relation of $\Delta$$\omega$=3.93$\sigma$($cm^{-1}$/GPa), where l1 (GPa) is the residual strain in the GaN epilayers.

• Journal of Sensor Science and Technology
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• v.31 no.1
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• pp.31-35
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• 2022

The efficacy improvement of the light emitting diode (LED) was studied for the realization of small-size, low power consumption, and highly sensitive bio-sensor instrument. The performance of the LED with Mg delta-doping at the interface of AlGaN/GaN super-lattice in p type cladding layer was simulated. The device with Mg delta-doping showed improved current, radiative recombination rate, electroluminescence, and light output power compared to the conventional LED structure. Under the bias condition of 5 V, the improved device exhibited 20.8% increase in the light output power. This is attributed to the increment of hole concentration from stable ionization of Mg in p type cladding layer. This result is expected to be used for the miniaturization, power saving, and sensitivity improvement of the bio-sensor system.

• Transactions on Electrical and Electronic Materials
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• v.16 no.2
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• pp.78-81
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• 2015

Pure ZnO and ZnO nanowires doped with 3 wt.% Ga (‘3GZO’) were grown by pulsed laser deposition in a furnace system. The doping of Ga in ZnO nanowires was analyzed by observing the optical and chemical properties of the doped nanowires. The diameter and length of nanowires were under 200 nm and several ${\mu}m$, respectively. Changes of significant resistance were observed and the sensitivities of ZnO and 3GZO nanowires were compared. The sensitivities of ZnO and 3GZO nanowire sensors measured at 300℃ for 1 ppm of ethanol gas were 97% and 48%, respectively.

• Journal of the Semiconductor & Display Technology
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• v.6 no.4
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• pp.29-32
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• 2007

Zinc gallate, $ZnGa_2O_4:Mn^{2+}$ co-doped with different concentrations of $Mg^{2+}$ (0.001- 0.5 mol%) was prepared by solid state synthesis method. These compositions were investigated for their photoluminescence and cathodoluminescence properties. The optimized composition $Zn_{0.990}Mg_{0.005}Ga_2O_4:Mn_{0.005}$ shows higher luminescence intensity compared to the parent phosphor. The intense green emission peak was found at 504 nm. The $Mg^{2+}$ doping does not affect much the decay time. It remains <10 ms for these compositions which make them potential candidate for application in TV screens.

• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.325-329
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• 1996

We report on p-type arsenic doping of metalorganic vapor phase epitaxially (MOVPE) grown HgCdTe on (100) GaAs. HgCdTe was grown at $370^{\circ}C$ in a horizontal reactor with using dimethy-cadmium, diisoprophyltelluride, and elemental Hg. We used tris-dimethylaminoarsenic (DMAAs) as the metalorganic for p-doping. 4micron thick CdTe and subsequently 10micron thick HgCdTe were grown on (100) GaAs substrate. Interdiffused multilayer process in which thin CdTe and HgTe layers are grown alternately and interdiffused to obtain homogeneous HgCdTe alloys was used. Arsenic was doped during CdTe growth cycle. After growth HgCdTe was annealed at $415^{\circ}C$ for 15 min and then annealed again at $220^{\circ}C$ for 3 hr, both with Hg-saturate condition. We could obtain p-doping from 2.5$\times$$10^{16}$ to 6.6$\times$$10^{17}$$cm^{-3}$, depending on the DMAAs partial pressure. With the dual Hg-annealing, activation of arsenic was aboutt 90%, which was confirmed by SIMS measurement. With only low temperature annealing at $220^{\circ}C$ for 3hr, activation efficiency was about 50%.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.128.2-128.2
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• 2014

Long-wave infrared detectors using the type-II InAs/GaSb strained superlattice (T2SL) material system with the nBn structure were designed and fabricated. The band gap energy of the T2SL material was calculated as a function of the thickness of the InAs and GaSb layers by the Kronig-Penney model. Growth of the barrier material (Al0.2Ga0.8Sb) incorporated Te doping to reduce the dark current. The full width at half maximum (FWHM) of the 1st satellite superlattice peak from the X-ray diffraction was around 45 arc sec. The cutoff wavelength of the fabricated device was ${\sim}10.2{\mu}m$ (0.12eV) at 80 K while under an applied bias of -1.4V. The measured activation energy of the device was ~0.128 eV. The dark current density was shown to be $1.2{\times}10^{-5}A/cm^2$ at 80 K and with a bias -1.4 V. The responsivity was 1.9 A/W at $7.5{\mu}m$ at 80K and with a bias of -1.9V.