광통신용 GaAs 기반 1.3 ㎛ GaAsSb/InGaAs와 GaAsSb/InGaNAs 양자우물 레이저의 광학적특성 시뮬레이션

박승환 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.1

Optical gain characteristics of 1.3㎛ type-II GaAsSb/InGaNAs/GaAs trilayer quantum well structures were studied using multi-band effective mass theory. The results were compared with those of 1.3㎛ GaAsSb/InGaNAs/GaAs trilayer quantum well structures. In the case of 1.3 ㎛ GaAsSb/InGaNAs/GaAs trilayer quantum well structure, the energy difference between the first two subbands in the valence band is smaller than that of 1.3 ㎛ GaAsSb/InGaNAs/GaAs trilayer quantum well structure. Also, 1.3 ㎛ GaAsSb/InGaNAs/GaAs trilayer quantum well structure shows larger optical gain than 1.3 ㎛ GaAsSb/InGaNAs/GaAs trilayer quantum well structure. This means that GaAsSb/InGaNAs/GaAs system is promising as long-wavelength optoelectronic devices for optical communication. 본 연구에서는 1.3㎛ 파장을 가진 type-II GaAsSb/InGaNAs 양자우물 구조와 GaAsSb/InGaAs 양자우물 레이저의 특성을 비교연구하였다. 그 결과, InGaNAs을 장벽으로 사용한 양자우물 구조가 InGaAs을 장벽으로 사용한 경우보다 더 큰 광학적 이득을 보여주었으며, 이것은 InGaNAs을 장벽으로 사용한 양자우물 구조의 경우 전도띠 파동함수의 confinement 가 더 커짐에 따라 밴드가장자리에서의 광학적 매트릭스요소가 0.078 에서 0.095 로 증가하였기 때문인 것으로 설명이 가능하였다. 또한, InGaNAs을 장벽으로 사용한 경우 처음 두 부밴드사이의 에너지 간격이 InGaAs을 장벽으로 사용한 경우보다 작음이 보여졌다. 이것은 GaAsSb/InGaNAs 양자우물 시스템이 광통신용 광원으로서 장점을 가지고 있음을 의미하고 있다.

Linewidth Enhancement Factor of Type-II GaAsSb/GaInAs/GaAs Trilayer Quantum Well Lasers

Seoung-Hwan Park,Hwa-Min Kim,김종재 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.6

The linewidth enhancement factor of type-II GaAsSb/GaInAs/GaAs trilayer QW structures was investigated numerically by using the non-Markovian gain model with many-body effects. In the case of relatively thin well widths below 55 A, the linewidth enhancement factor of the GaAsSb/GaInAs/GaAs trilayer QW structure is nearly the same as that of the GaAsSb/GaAs single QW structure. In the range of relatively thick well widths, on the other hand, the GaAsSb/GaInAs/GaAs system shows a larger linewidth enhancement factor than the GaAsSb/GaAs system. This is mainly attributed to the fact that the GaAsSb/GaInAs/GaAs system has a smaller differential gain, dg/dN, than the GaAsSb/GaAs system. The linewidth enhancement factor of type-II GaAsSb/GaInAs/GaAs trilayer QW structures was investigated numerically by using the non-Markovian gain model with many-body effects. In the case of relatively thin well widths below 55 A, the linewidth enhancement factor of the GaAsSb/GaInAs/GaAs trilayer QW structure is nearly the same as that of the GaAsSb/GaAs single QW structure. In the range of relatively thick well widths, on the other hand, the GaAsSb/GaInAs/GaAs system shows a larger linewidth enhancement factor than the GaAsSb/GaAs system. This is mainly attributed to the fact that the GaAsSb/GaInAs/GaAs system has a smaller differential gain, dg/dN, than the GaAsSb/GaAs system.

광통신용 GaAs 기반 1.3 μm GaAsSb/InGaAs와 GaAsSb/InGaNAs 양자우물 레이저의 광학적특성 시뮬레이션

박승환,Park, Seoung-Hwan 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.1

Optical gain characteristics of $1.3{\mu}m$ type-II GaAsSb/InGaNAs/GaAs trilayer quantum well structures were studied using multi-band effective mass theory. The results were compared with those of $1.3{\mu}m$ GaAsSb/InGaNAs/GaAs trilayer quantum well structures. In the case of $1.3{\mu}m$ GaAsSb/InGaNAs/GaAs trilayer quantum well structure, the energy difference between the first two subbands in the valence band is smaller than that of $1.3{\mu}m$ GaAsSb/InGaNAs/GaAs trilayer quantum well structure. Also, $1.3{\mu}m$ GaAsSb/InGaNAs/GaAs trilayer quantum well structure shows larger optical gain than $1.3{\mu}m$ GaAsSb/InGaNAs/GaAs trilayer quantum well structure. This means that GaAsSb/InGaNAs/GaAs system is promising as long-wavelength optoelectronic devices for optical communication.

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.

Effects of Modulation Doping on the Optical Properties of a Type-II 1.55-µm GaAsSb/InGaNAs/GaAs Trilayer Quantum-Well Structure

김종재,Seoung-Hwan Park 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.4

The effects of modulation doping on the optical properties of a GaAsSb/InGaNAs/GaAs trilayer quantum well (QW) structure are investigated by using a self-consistent method. As modulation doping increases, the potential well near the GaAsSb layer becomes sharper and deeper because the electric screening field is directed toward the center of the well and attracts the electrons toward the GaAsSb well. The interband transition wavelength gradually decreases with increasing modulationdoping density, and the optical gain is shown to be enhanced due to the band-bending effect. The increase in the optical gain can be explained by the fact that the optical matrix element increases with increasing modulation-doping density.

Optical Gain of Type-II 1.55-μm GaAsSb/InGaNAs/GaAs Trilayer Quantum Wells

박승환 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.4

The optical gain characteristics of type-II GaAsSb/InGaNAs/GaAs trilayer quantum well (QW) structures with a wavelength of 1.55 μm were investigated by using the multiband effective-mass theory. The carrier density dependence of the transition wavelength is shown to decrease with decreasing InGaNAs layer width. The GaAsSb/InGaNAs/GaAs trilayer QW structure shows an optical gain that is much larger than that of the GaAsSb/GaAs single QW structure. This can be explained by the fact that the confinement of the electron in the conduction band is enhanced due to the deep potential well of the InGaNAs barrier. Also, the optical gain is observed to increase greatly with decreasing InGaNAs layer width because of the type-I-like emission from a trilayer QW with a thin InGaNAs layer.

Modulation Doping Effect in the Optical Gain of Type-II GaAsSb/GaAs Quantum-Well Structures

박승환 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.4

The effect of modulation doping on the optical gain characteristics of type-II GaAsSb/GaAs quantum-well (QW) lasers was investigated using a self-consistent method. The interband transition energy gradually increased with n-type modulation doping. However, in the case of p-type modulation doping, the rate of increase was found to be smaller than that of n-type modulation doping. The optical gain was found to be largely enhanced by an increasing n-type modulation doping density. This could be explained by the fact that the optical matrix element was greatly increased due to the band-bending effect. On the other hand, in the case of p-type modulation doping, the optical gain was slightly smaller than that for n-type modulation doping because the optical matrix element was reduced by the negative charge from the ionized acceptors near the well. The effect of modulation doping on the optical gain characteristics of type-II GaAsSb/GaAs quantum-well (QW) lasers was investigated using a self-consistent method. The interband transition energy gradually increased with n-type modulation doping. However, in the case of p-type modulation doping, the rate of increase was found to be smaller than that of n-type modulation doping. The optical gain was found to be largely enhanced by an increasing n-type modulation doping density. This could be explained by the fact that the optical matrix element was greatly increased due to the band-bending effect. On the other hand, in the case of p-type modulation doping, the optical gain was slightly smaller than that for n-type modulation doping because the optical matrix element was reduced by the negative charge from the ionized acceptors near the well.

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.

Large Rashba Effect In GaAsSb/InGaAs RTDs at High Temperatures

J. Silvano de Sousa 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.10

A large resonance splitting is seen when an in-plane magnetic field is applied in non-magnetic InGaAs/GaAsSb/InGaAs resonant tunneling diodes (RTDs). The peak splitting can be explained in terms of the Rashba effect, which is enhanced by the in-plane acceleration that the electrons suffer under the action of the magnetic field. The Rashba splitting reaches values up to 30 meV for B = 5 T and stands temperatures above T = 180 K. The resonance peak splitting provides a new method to determine the Rashba parameter (α). The measured Rashba parameter in these RTDs range from = 0.38 eVÅ to α = 0.78 eVÅ.

Modulation-Doping Effect on the Linewidth Enhancement Factor of Type-II GaAsSb/GaAs Quantum-Wel Lasers

김종재,김화민,박승환 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.6

Modulation-doping effects on the linewidth enhancement factor (αe) of type-I GaAsSb/GaAs quantum-wel (QW) lasers are investigated theoreticaly by using a self-consistent method. In the case of p-type modulation doping, the linewidth enhancement factor rapidly increases with the doping density. In the case of n-type modulation doping, on the other hand, the variation of αe shows only a smooth ridge line with increasing doping density. In addition, the linewidth enhancement factor for p-type modulation doping is always shown to be larger than that for n- type modulation doping. This is mainly due to the fact that the absolute value of the incremental refractive index change is greater than that forn-type modulation doping.