• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 춘계학술발표강연 및 논문개요집
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• pp.90-90
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• 2003

• 한국전기전자재료학회논문지
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• 제18권9호
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• pp.781-786
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• 2005

The binding energy in the n-type $GaAs/Al_xGa_{1-x}As$ quantum well is calculated. The shooting method, modified from the finite difference method, is used for the calculation of the subband energy level and its wave function. In order to account tot the change of the potential energy due to the charged particles, impurities and electrons, the self consistent method is employed. The wave function used for the calculation of the binding energy is assumed to be composed of the envelope function and hydrogenic 1s function. Then, the binding energies calculated by taking into account lot two different types of the hydrogenic 1s function are compared.

• JSTS:Journal of Semiconductor Technology and Science
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• 제9권3호
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• pp.125-135
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• 2009

An analytical 2-dimensional model to explain the small signal and noise properties of an AlGaN/GaN modulation doped field effect transistor has been developed. The model is based on the solution of two-dimensional Poisson's equation. The developed model explains the influence of Noise in ohmic region (Johnson noise or Thermal noise) as well as in saturated region (spontaneous generation of dipole layers in the saturated region). Small signal parameters are obtained and are used to calculate the different noise parameters. All the results have been compared with the experimental data and show an excellent agreement and the validity of our model.

• The Journal of Korean Physical Therapy
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• 제15권3호
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• pp.16-44
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• 2003

Skeletal muscle regeneration is a vital process for various muscle myopathies and muscular adaptation to physiological overload. Angiogenesis is the key event in the process of muscle regeneration, and vascular endothelial growth factor(VEGF) plays an important role in it. The purpose of this study was to evaluate the effect of GaAlAs(830nm) laser and immunoreactivity of VEGF on angiogenesis after muscle contusion injury. Muscle contusion injury was induced in the triceps surae muscle by dropping a metal bead(31.4g). GaAlAs laser irradiation(power 20 mW, frequency 2000 Hz, treatment time 15 min) was applied directly to the skin of injured muscle daily for seven days. The experimental group I was irradiated immediately by laser after injury, whereas the experimental group II was irradiated after 1 day of injury. The control group was non-irradiated. The results of this study were as follows. 1. In morphological observation, there were no significant changes in experimental and control groups for 7 days. At 3 days, however, the splited muscle fibers were observed in experimental groups, and the muscle atrophy and granular tissue viewed at 7 days in control group. 2. The VEGF was expressed in muscle fiber that located in the interspace between gastrocnemius and soleus muscles. As the time coursed, the immunoreactivity of VEGF also seemed to be strong in the individual muscle fibers. 3. The experimental group I & II showed higher immunoreactivity of VEGF than control group(p<0.05). Then, the experimental group I showed higher than group II especially(p<0.05). These data suggest GaAlAs semiconduct diode laser irradiation(830nm) enhanced angiogenesis in the skeletal muscle induced contusion injury, and immediate laser irradiation after injury promoted the angiogenesis greatly than after 1 day of injury.

• 전자공학회논문지D
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• 제34D권3호
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• pp.34-40
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• 1997

Intervalence subband absroption of normally incident infrared radiation in p-type InGaAs-InAlAs coupled quantum well (CQW) is theoretically investigated by the multiband effective mass formalism. By solving a 4*4 luttinger-kohn hamitonian, we calculate valence subband structures, intervalence subband transition matrix elements, and absorption coefficient spectrum in the CQW which consists of a wider well, a thinner well and a barreir between them. Using the flexible design parameters given to the valence band CQW structure, we show that the absorption coefficient profile can be tailored. For a carefully designed CQW, theabsorption coefficient cn be made to maintain a large value over a wider wavelength range of incident infrared radiation compared with that shown in intersubband absorption in usual single quantum well.

• 대한전자공학회논문지
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• 제24권3호
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• pp.445-452
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• 1987

In this paper, a model for characteristics in the AlxGa1-xAs layer of MODFET's is presented. The characteristics of conduction band in the AlxGa1-xAs layer is analyzed with the Fermi-Dirac statistics. And using the conduction band energy which is calculated with the numerical calculation method (false-Positon method), the variations of the electric-field distribution, the ionized donor concentration, and the two-dimensional electron gas density with gate voltage are calculated, respectively. The channel formation process for the parasitic MESFET operation in the MOD structure is also analyzed, and the characteristics in the AlxGa1-xAs layer is analytically modeled. The throretical results describe well the general characteristics in the MOD structure.

• 한국전자파학회논문지
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• 제15권3호
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• pp.258-264
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• 2004

본 논문에서는 40 ㎓ 대역 MMIC(Monolithic Microwave Intergrated Circuit) 이중평형 star 혼합기를 비아 공정이 있는 GaAs substrate(두께 4 mil)상에서 설계 및 제작, 측정하였다. 이중평형 star 혼합기를 구현하기 위해 발룬회로와 다이오드 설계가 필요했다. 발룬회로는 microstrip과 CPS(Coplanar Strip)를 이용하여 새로운 구조를 제안하여, 2 ㎓ 대역으로 주파수를 낮추어 새로운 구조의 발룬 성능을 PCB로 제작하여 확인한 바 있다. 이를 바탕으로 40 ㎓에서 MMIC 발룬을 설계하였다. 제안된 발룬은 비아 공정이 포함된 MMIC 회로에 적 합하며, 이중평형 혼합기 구현에 쉽게 적용 가능하다는 특징이 있다. 다이오드는 p-HEMT를 사용하는 밀리미터파 대역의 다른 MMIC 회로들과의 호환성을 고려하여, p-HEMT 공정을 기반으로 한 쇼트키 다이오드를 설계하였다. 이를 이용 제안한 발룬회로와 다이오드를 조합하여, 이중평형 star 혼합기를 구현하였다. 혼합기의 측정 결과 LO전력이 18 ㏈m일 때, 변환손실 약 30 ㏈를 얻었다. 이는 p-HEMT의 AlGaAs/InGaAs 층에 의한 다이오드 때문이며, p-HEMT구조에서 AlGaAs층을 식각하여 단일 접합 다이오드를 만들면 혼합기의 성능이 개선될 것으로 예상된다.

• 전자공학회논문지D
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• 제35D권5호
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• pp.80-86
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• 1998

Material characterizations were performed for In$_{0.53}Ga_{0.47}As/In$_{0.52}Al_{0.48}$/As MQWs grown on InP substrates by low-temperature modlecular beam epitaxy. MQW samples were grwon at different temperatures of 200.deg.C, 300.deg. C and 500.deg. C, and doped with 10$^{18}$ cm$^{3}$ Be. High resolution x-ray diffraction measurement showed the change in crystal qualities according to growth temperature. Hall measurement showed the changes in carrier concentrations and mobilities for different growth temperatures. The optical properties of MQW samples were investigated with photoluminescence and fourier-transform infrared spectroscopy measurements.

• Transactions on Electrical and Electronic Materials
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• 제12권4호
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• pp.140-143
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• 2011

The growth and characterization of $In_{0.5}Ga_{0.5}As/In_{0.5}Al_{0.5}As$ narrow-gap inverted high electron mobility transistor structures, developed as a candidate material for spin-injection devices, are presented in this study. We have grown samples possessing surface $In_{0.5}Ga_{0.5}As$ channels of different thicknesses (30 nm and 60 nm) both with and without a thin 3 nm $In_{0.5}Ga_{0.5}As$ cap layer by using molecular beam epitaxy. We then investigated the in-plane transport properties as well as the Rashba spin-orbit coupling constant of the two-dimensional electron gas confined at the heterojunction interface.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.207-213
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• 1996

A ternary compound semiconductor $Al_{x}$-Ga/1-x/Sb crystals which have energy gap from 0.7eV to 1.6ev at room temperature with the composition ratio were grown by using the vertical Bridgman method. The characteristics of $Al_{x}$-Ga/1-x/Sb were investigated in this study. The lattice constants of $Al_{x}$-Ga/1-x/Sb crystals with the composition ratio were appeared from 6.096$\AA$ to 6.135$\AA$ with the composition ratio. The electrical properties of the $Al_{x}$-Ga/1-x/Sb crystals measured the Hall effect by van der Pauw method at the magnetic field of 3 kilogauss and at room temperature. The resistivity of Te-doped $Al_{x}$-Ga/1-x/Sb crystals increased from 0.771 $\Omega$-cm to 5 $\Omega$-cm at room temperature with increasing the composition ratio. The mobility of Te-doped $Al_{x}$-Ga/1-x/Sb crystals varied with the composition ratio x, within the following three different regions, such as GaSb-like (0$\leq$x$\leq$0.3), intermediate (0.3$\leq$x$\leq$0.4) and AlSb-like (0.4$\leq$x$\leq$1).eq$1).