약속어음의 발행인과 배서인이 소지인에 대하여 지는 합동책임

박승환 한국상사판례학회 1989 상사판례연구 Vol.3 No.1

Effect of Modulation Doping on the Spontaneous Emission Characteristics of Wurtzite GaN/AlGaN Quantum Well Structures

박승환 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.6

The effect of modulation doping on the spontaneous emission characteristics of wurtzite GaN/AlGaN QW structureswas investigated. The overall potential profile is nearly not affected by the modulation doping, except for the fact that the potential well bottom in the conduction band becomes deeper while that in the valence band becomes shallower. The interband transition wavelength gradually decreases with increasing injection carrier density due to an increase in the screening electric field. In the range of relatively low carrier densities, the spontaneous emission coefficient is observed to be greatly enhanced with increasing doping density. This can be explained mainly by the fact that the quasi-Fermi level separation is increased by modulation doping because the optical matrix element is nearly not affected by doping. Also, the spontaneous emission coefficient is shown to be nearly saturated at a higher modulation doping density (Nδ = 7 × 1012 cm−2).

Barrier Effects on Exciton Binding Energies in Zinc-blende CdZnSe/ZnSSe Quantum Well Structures

박승환,김종재,김화민 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.1

Barrier effects on the exciton binding energies of CdZnSe/ZnSSe quantum well (QW) structures were investigated within the framework of effective mass theory. The exciton binding energy gradually increases with increasing S composition in the barrier for the QW structure with a relatively thin well width (Lw = 10 Å). On the other hand, in the case of the QW structure with a relatively thick well width (Lw = 30 Å), the exciton binding energy is found to be a weak function of the S composition in the barrier. Also, the QW structure with a thin well width (Lw = 10 Å) has a larger exciton binding energy than that with a thick well width (Lw = 30 Å). This can be explained by the fact that the three-dimensional character of the exciton is restored due to the increase of the spatial extent of the electron and the hole wavefunctions for the QW structure with the thick well width.

1.3 및 1.55㎛ GaAsSb/InGaNAs/GaAs Trilayer 양자우물 구조의 광학적이득 특성

박승환 한국물리학회 2010 새물리 Vol.60 No.10

The optical gain characteristics of 1.3 ㎛ GaAsSb/InGaNAs/GaAs trilayer quantum well structures were studied using multi-band effective mass theory. The results were compared with those of 1.55㎛ GaAsSb/InGaNAs/GaAs trilayer quantum well structures. The transition wavelength gradually decreases with increasing carrier density due to the band-bending effect. In the case of the 1.3㎛ GaAsSb/InGaNAs/GaAs trilayer quantumwell structure, the rate of decrease is shown to be smaller than that of the 1.55㎛GaAsSb/InGaNAs/GaAs trilayer quantum well structure due to a reduced band-bending effect. Also, the 1.3 ㎛ quantumwell structure shows a larger optical gain than the 1.55 ㎛ quantumwell structure because the former has a larger optical matrix element than the latter. On the other hand, the quasi-Fermi level of the 1.3㎛ quantum well structure is slightly smaller than that of the 1.55 ㎛ quantumwell structure. 본 연구에서는 1.3 ㎛ 와 1.55 ㎛ 파장을 가진 type-Ⅱ GaAsSb /InGaNAs / GaAs trilayer 양자우물 레이저에 대한 광학적특성을 조사하고이것을 서로 비교 연구하였다. 천이 파장은 운반자 밀도가 증가함에 따라band-bending 효과에 의해 감소하였으며, 특히 1.55 ㎛ 의 양자우물구조의 경우 1.3 ㎛ 의 양자우물 구조에 비해 감소 효과가 더 크게나타났다. 1.3 ㎛ 의 양자우물 구조가 1.55 ㎛ 의 양자우물 구조보다 더 큰 광학적 이득 값을 보여주었는데, 이것은 주로 광학적매트릭스 요소가 크기 때문인 것으로 나타났다. 반면, 준페르미 준위는포텐셜 우물의 깊이가 더 깊은 1.55 ㎛ 의 양자우물 구조의 경우가더 크게 나타났다.

Optical Properties of Green InGaN/GaN Quantum-Wel Light-Emitting Diodes with Embedded AlGaN Layer

박승환,Yong-Tak Lee,Jongwoon Park 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.1

The optical characteristics of green InGaN/GaN double-quantum-well (QW) structures with embedded AlGaN layers are investigated using the multiband effective mass theory. These results are compared with those of single QW structure without a layer. A double QW structure has a much larger spontaneous emission than a single QW structure for a relatively thick well width (Lw= 5 nm) because a double QW structure has a larger optical matrix element and a smaller effecive well width than a single QW structure. The inclusion effect of a layer is found to be dominant at a relatively thick well width. However, the double QW structure is shown to need a slightly larger In composition to obtain the same transition wavelength as the single QW structure.

Many-Body Optical Gain in Zinc-Blende GaN/AlGaN Quantum Wells with (001), (111) and (110) Crystal Orientations

박승환 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.3

Many-body optical gain in (001)-, (111)- and (110)-oriented zinc-blende GaN/AlGaN quantum-wells (QWs) was investigated by using a non-Markovian optical gain model with many-body effects. The transition energy of the (110)-oriented QW structure was shown to be larger than that of the (001)- or the (111)-oriented QW. For a given carrier density, the (111)-oriented QW structure has a smaller optical gain and a larger transparency carrier density than the (001)- or the (110)-oriented QW structure. This can be explained by the fact that the (111)-oriented QW has a smaller matrix element and a larger heavy-hole effective mass than the (001)- or the (110)-oriented QW structure. In addition, the (111)-oriented QW structure showed a larger transparency carrier density compared to the (001)- or the (110)-oriented QW. The increase in the transparency carrier density observed in the (111)-oriented QW is attributed to the fact that the quasi-Fermi level separation is reduced due to the larger hole effective mass. Many-body optical gain in (001)-, (111)- and (110)-oriented zinc-blende GaN/AlGaN quantum-wells (QWs) was investigated by using a non-Markovian optical gain model with many-body effects. The transition energy of the (110)-oriented QW structure was shown to be larger than that of the (001)- or the (111)-oriented QW. For a given carrier density, the (111)-oriented QW structure has a smaller optical gain and a larger transparency carrier density than the (001)- or the (110)-oriented QW structure. This can be explained by the fact that the (111)-oriented QW has a smaller matrix element and a larger heavy-hole effective mass than the (001)- or the (110)-oriented QW structure. In addition, the (111)-oriented QW structure showed a larger transparency carrier density compared to the (001)- or the (110)-oriented QW. The increase in the transparency carrier density observed in the (111)-oriented QW is attributed to the fact that the quasi-Fermi level separation is reduced due to the larger hole effective mass.

열영상 카메라가 결합된 프리즘 도트사이트 개발

박승환,정보선,이동희 한국안광학회 2014 한국안광학회지 Vol.19 No.4

This study relates to the development of the prism dot-sight combined with the thermal imagingcamera. Methods: We have placed a reflector designed to the doublet type in the front of a BS (beam splitting)prism, have placed an OLED panel and a dot reticle generator to the top and bottom of the reflecting surface ofthe BS prism, and have placed a detachable magnifier between the BS prism and the observer by which theobserver can see the magnified image of the OLED panel. By doing this, we were able to configure the new typeprism dot-sight combined with the thermal imaging camera. Results: By placing the removable magnifierdesigned with a new type between the BS prism and the observer, we could design the new type prism dot-sightwhich performs the role of the dot sight by removing the magnifier during the day-time, and performs the role ofthe night scope during the night-time by which we can observe the enlarged image of the thermal imagingcamera through the BS prism by attaching the removable magnifier. Conclusions: In this study, we havedeveloped the prism dot-sight combined with the thermal imaging camera which is able to play the role of theday or night scope selectively, by disposing the designed magnifier characterized by the focal length of 44 mm,the viewing angle of ±7.0o, and the MTF value of 0.5 or more at the criterion of 50 lp/mm and the 0.7 fieldbetween the BS prism and the observer. By doing so, we could design and fabricate the new type prism dot-sightcombined with the thermal imaging camera which can further increase the rapidity of firing and provide moreconvenience in the mounting of a firearm than the detachable combination of an existing dot sight and an existingnight scope. 본 연구는 열영상 카메라가 결합된 프리즘 도트사이트의 개발에 관한 것이다. 방법: 우리는 BS(beamsplitting) 프리즘 전방에 doublet 형태로 설계된 반사경을 배치하고, BS프리즘의 반사면의 상하에는 도트시표 발생부와 OLED 패널을 배치하며, BS 프리즘과 관찰자 사이에 OLED 패널의 영상을 확대해 볼 수 있도록 하는 착탈식확대경을 배치하였다. 이렇게 함으로써 새로운 형태의 열영상 카메라가 결합된 프리즘 도트사이트의 광학계를 구성할 수 있었다. 결과: 새로운 타입으로 설계되어진 착탈식 확대경을 BS 프리즘과 관찰자 사이에 배치함으로서 주간에는 착탈식 확대경을 제거하여 도트사이트 역할을 하며, 야간에는 착탈식 확대경을 부착하여 열영상 카메라의 확대된 영상을 BS 프리즘을 통해서 볼 수 있도록 하여 야시경 역할을 하는 새로운 형태의 도트사이트 광학계를 설계하였다. 결론: 본 연구에서 우리는 초점거리 44 mm, 화각 ±7.0o, 50 lp/mm 기준으로 0.7 Field에서는 0.5 이상의MTF를 가지도록 설계되어진 확대경을 BS 프리즘과 관찰자 사이에서 배치함으로서 선택적으로 주야 조준경 역할을 할 수 있는 열영상 카메라가 결합된 프리즘 도트사이트를 개발하였다. 이렇게 함으로써 우리는 기존의 도트사이트와 야간조준경의 착탈식 조합보다 사격의 신속성을 더욱 높일 수 있으며 총기류에의 장착에 있어서 보다 편리함을 제공해주는 새로운 형태의 열영상 카메라가 결합된 프리즘 도트사이트의 광학계를 설계 개발할 수 있었다.

Theoretical Study of a Two-dimensional Electron Gas in Wurtzite ZnO/MgZnO Heterostructures and Comparison with Experiment

박승환,홍우표,김종재,안도열 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.10

The effect of polarization on a two-dimensional electron gas in the ZnO/MgZnO heterostructure were investigated by using an effective mass theory. The O-face MgZnO/ZnO structure is shown to have a larger sheet carrier density than the Zn-face structure. This can be explained by the fact that, in the case of the O-face, the ZnO layer is under tensile strain, and the strain-induced polarization is parallel to the orientation of the spontaneous polarization. The calculated results for the O-face agree well with the experiment. Also, the contribution of additional donor impurities on the electron sheet concentration is shown to be less effective when the Mg mole fraction is large.

Optical Gain Characteristics of Long-wavelength Type-II InGaAs/GaPAsSb Quantum Wells Grown on GaAs Substrates

박승환 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.58 No.3

The ptical gain characteristics of GaPAsSb/InGaAs quantum well (QW) structures are investigated using the multiband effective-mass theory. These results are also compared with those of type-II GaAsSb/GaAs QW structures. The optical gain is improved, and the peak wavelength is blueshifted with increasing GaP composition in the GaPAsSb well. The improvement in the optical gain can be explained by an increase in the optical matrix element. However, quasi-Fermi level separations slightly decrease with increasing GaP composition in the GaPAs layer. This is attributed to the fact that the conventional GaAsSb/InGaAs/GaAs structure shows a larger energy spacing between the first subband (HH1) and higher subbands in the valence band structure.

Al Composition Dependence of the Optical Gain Characteristics of a-plane Al-rich AlGaN/AlN Quantum-well Structures

박승환 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.2

The Al composition dependence of the optical gain characteristics of a-plane Al-rich AlGaN/AlN quantum-well (QW) structures was investigated using the multiband effective-mass theory and the non-Markovian optical model with the many-body effect. quantum-well (QW) structures were investigated using the multiband effective-mass theory and non-Markovian optical model with the many-body effect. The optical gain for the x′-polarization is shown to be much larger than that for the y′-polarization because the optical matrix element for the x′-polarization is larger than that for the y′-polarization. The optical gain for the x′-polarization gradually decreases with increasing Al composition. In the case of the c-plane, the intensity of the optical gain increases with increasing Al composition because of the reduction in the internal field. However, the optical gain is shown to decrease rapidly with increasing Al composition when the Al composition exceeds 0.75.