• Title, Summary, Keyword: Quantum well

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High efficiency multiple quantum well device structure in red phosphorescent OLEDs

  • Park, Tae-Jin;Jeon, Woo-Sik;Jang, Jin;Pode, Ramchandra;Kwon, Jang-Hyuk
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.196-199
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    • 2009
  • We report the multiple quantum well (MQW) structure for highly efficient red phosphorescent OLEDs. Various triplet quantum well devices from a single well to five quantum wells are realized using a wide band-gap hole and electron transporting layers, narrow band-gap host and dopant material, and charge control layers (CCL). The maximum external quantum efficiency of 14.8 % with a two quantum well device structure is obtained, which is the highest value among the red phosphorescent OLEDs using same dopant.

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Optical Properties of a ZnO-MgZnO Quantum-Well

  • Ahn, Do-Yeol;Park, Seoung-Hwan
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.6 no.3
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    • pp.125-130
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    • 2006
  • The optical gain and the luminescence of a ZnO quantum well with MgZnO barriers is studied theoretically. We calculated the non-Markovian optical gain and the luminescence for the strained-layer wurtzite quantum well taking into account of the excitonic effects. It is predicted that both optical gain and luminescence are enhanced for the ZnO quantum well when compared with those of InGaN-AlGaN quantum well structure due to the significant reduction of the piezoelectric effects in the ZnO-MgZnO systems.

Impact ionization rate of the highly-doped AlGaAs/GaAs quantum well (고준위 도핑된 AlGaAs/GaAs 양자 우물의 충돌 이온화율)

  • 윤기정;황성범;송정근;홍창희
    • 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.

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Simulation of Optical Characteristics of 1.3 μm GaAs-Based GaAsSb/InGaAs and GaAsSb/InGaNAs Quantum Well Lasers for Optical Communication (광통신용 GaAs 기반 1.3 μm GaAsSb/InGaAs와 GaAsSb/InGaNAs 양자우물 레이저의 광학적특성 시뮬레이션)

  • Park, Seoung-Hwan
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.24 no.1
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    • pp.1-6
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    • 2011
  • 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.

Photoluminescence study in GaAs/AlGaAs multi-quantum well structure by hydrogen passivation (수소화 처리에 의한 GaAs/AIGaAs 다중양자우물의 PL 연구)

  • Park, Se-Ki;Lee, Cheon;Jung, Min
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.468-472
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    • 1997
  • The effect of the surface state on the quantum efficiency of underlying GaAs/AlGaAs multi-quantum well(MQW) structures consisting of three GaAs quantum wells with different thickness, is studied by low temperature photoluminescence(PL). The structure was grown by molecular beam epitaxy(MBE) on (100) GaAs substrate. The thickness of three GaAs quantum wells was 3, 6 and 9 nm, respectively. The MQWs were placed apart from 50 nm AlGaAs edge-barriers including two inner-barriers with 15 nm in thickness. The samples used in this study were prepared with different growth temperatures. Particularly, the hydrogen passivation effect to the 9 nm quantum well located at near surface appeared much stronger than any others. Transition energy and optical gain related to the hydrogen passivation effects on the multi-quantum well structure was calculated by transfer matrix method.

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Optical Transitions of a InGaP-AlInGaP Semiconductor Single Quantum Well in Magnetic Fields

  • Kim, Yong-Min;Sin, Yong-Ho;Song, Jin-Dong
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.332.1-332.1
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    • 2016
  • Application of magnetic fields is important to characterize the carrier dynamics in semiconductor quantum structures. We performed photoluminescence (PL) measurements from an InGaP-AlInGaP single quantum well under pulsed magnetic fields to 50 T. The zero field interband PL transition energy matches well with the self-consistent Poisson-Schr?dinger equation. We attempted to analyze the dimensionality of the quantum well by using the diamagnetic shift of the magnetoexciton. The real quantum well has finite thickness that causes the quasi-two-dimensional behavior of the exciton diamagnetic shift. The PL intensity diminishes with increasing magnetic field because of the exciton motion in the presence of magnetic field.

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Diamagnetic Shift of a InGaP-AlInGaP Semiconductor Single Quantum Well under Pulsed-magnetic Fields

  • Choi, B.K.;Kim, Yongmin;Song, J.D.
    • Applied Science and Convergence Technology
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    • v.24 no.5
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    • pp.156-161
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    • 2015
  • Application of magnetic fields is important to characterize the carrier dynamics in semiconductor quantum structures. We performed photoluminescence (PL) measurements from an InGaP-AlInGaP single quantum well under pulsed magnetic fields to 50 T. The zero field interband PL transition energy matches well with the self-consistent Poisson-$Schr{\ddot{o}}dinger$ equation. We attempted to analyze the dimensionality of the quantum well by using the diamagnetic shift of the magnetoexciton. The real quantum well has finite thickness that causes the quasi-two-dimensional behavior of the exciton diamagnetic shift. The PL intensity diminishes with increasing magnetic field because of the exciton motion in the presence of magnetic field.

The Effect of Quantum Well Structure on the Characteristics of GaN-based Light-Emitting Diode (양자 우물 구조가 GaN 기반 LED 특성에 미치는 영향)

  • Lee, Jae-Hyun;Yeom, Keesoo
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.251-254
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    • 2012
  • In this paper, the output characteristics of GaN-based LED considering quantum well structure are analyzed. The basic structure of the LED consists of active region of GaN barrier and InGaN quantum well between AlGaN EBL(Electron Blocking Layer) and AlGaN HBL(Hole Blocking Layer) on GaN buffer layer. The output power, internal quantum efficiency characteristics of LED active region considering thickness of quantum well, number of quantum well and doping of barrier are analyzed using ISE-TCAD.

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Magneto-optical Measurements of Semiconductor Quantum Structures in Pulsed-magnetic Fields

  • Kim, Yongmin
    • Applied Science and Convergence Technology
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    • v.23 no.1
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    • pp.1-13
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    • 2014
  • Semiconductor quantum structures are often characterized by their energy gaps which are modified by the quantum size effect. Energy levels in semiconductors can be realized by optical transitions within confined structures. Photoluminescence spectroscopy in magnetic fields at low temperatures has proved to be a powerful technique for investigating the electronic states of quantum semiconductor heterostructures and offers a complimentary tool to electrical transport studies. In this review, we examine comprehensive investigations of magneto-excitonic and Landau transitions in a large variety of undoped and doped quantum-well structures. Strong magnetic fields change the diamagnetic energy shift of free excitons from quadratic to linear in B in undoped single quantum well samples. Two-dimensional electron gas induced by modulation doping shows pronounce quantum oscillations in integer quantum Hall regime and discontinuous transition at ${\nu}=1$. Such discontinuous transition can be explained as the formation of spin waves or Skyrmions.

Optical Properties of an Exciton in Quantum Well Structures

  • Lee, Jong-Chul
    • Journal of Electrical Engineering and information Science
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    • v.3 no.3
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    • pp.385-390
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    • 1998
  • In this paper, the oscillator strengths of both the heavy-hole and the light-hole excitons in GaAs-A\ulcornerGa\ulcornerAs and In\ulcornerGa\ulcornerAs-InP quantum wells with the effect of a magnetic field applied along the growth axis are studied. The calculation is carried out usig a variational approach, based on a simple trial exction wave function. The exciton oscillator strengths are found to decrease with increasing well width and to increase with the applied magnetic fields which lead to additional quantum confinement for moderately wide well sizes. Also, the oscillator strengths for the heavy-hole exciton are found to be large than those of the light-hole exciton in these quantum well structures.

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