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Optical Properties and Carrier Transport in a Biased GaAs/AlAs Asymmetric Quintuple-Quantum-Well Superlattice
摘要： Photoluminescence (PL) properties and carrier transport in a GaAs/AlAs asymmetric quintuple-quantum well superlattice (AQQW-SL) were investigated. Since AQQWs are separated by very thin AlAs barriers, various carrier transport phenomena are expected due to the strong coupling of wave functions between the Γ states in the GaAs QWs and the X states in the AlAs barriers. A 20-period AQQW was embedded in the i-layer of a pin diode. A PL signal between the ground Γ and the heavy hole (hh) states was observed around 740 nm. However, another PL branch was observed at about 665 nm around 6 V. Based on the numerical calculation of the Γ and X wave functions, the electron transport from the X state in the thick AlAs barrier (X11) to the Γ state in the third QW (Γ31) occurs at 6.1 V. Thus, a PL signal at 665 nm can be attributed to the recombination between Γ31 and hh11.
关键词： GaAs/AlAs,photoluminescence,asymmetric quintuple-quantum-well,superlattices
更新于2025-09-23 15:22:29
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Quantum Dots - Theory and Applications || Quantum Dots Prepared by Droplet Epitaxial Method
摘要： In this work, we are dealing with the droplet epitaxially prepared quantum dots. This technology is not only an alternative way of the strain induced technique to prepare quantum dots, but it allows us to make various shaped nano structures from various material. The present paper deals not only with the so called conventional shaped quantum dot but also with the ring shaped dot, with the inverted dot and with dot molecules as well. Their thechnology, opto-electronical and the structural properties are also discussed.
关键词： MBE,QD,AlGaAs,droplet epitaxy,AlAs,GaAs
更新于2025-09-11 14:15:04
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Epitaxial GaAs and pHEMT on aluminum-transformed AlAs nanofilms
摘要： Heterogeneous epitaxial growth between semiconductors and metals boosts novel device development and enables various applications. In this work, we have investigated the epitaxial growth of GaAs layers on top of a nanoscale aluminium-transformed AlAs film. The grown GaAs layers are single-crystalline and of high-quality, that has been evidenced by using various material characterization methods and by fabricating their high-electron mobility transistors. We found that an intriguing process named as “arsenidation” of aluminium film plays a key role in the successful epitaxy. Our work opens a window for growing semiconductor/metal hetero-structures for various device applications in the future.
关键词： epitaxial growth,pHEMT,arsenidation,AlAs,GaAs
更新于2025-09-04 15:30:14
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First-Principles Study of Point Defects in GaAs/AlAs Superlattice: the Phase Stability and the Effects on the Band Structure and Carrier Mobility
摘要： Advanced semiconductor superlattices play important roles in critical future high-tech applications such as aerospace, high-energy physics, gravitational wave detection, astronomy, and nuclear related areas. Under such extreme conditions like high irradiative environments, these semiconductor superlattices tend to generate various defects that ultimately may result in the failure of the devices. However, in the superlattice like GaAs/AlAs, the phase stability and impact on the device performance of point defects are still not clear up to date. The present calculations show that in GaAs/AlAs superlattice, the antisite defects are energetically more favorable than vacancy and interstitial defects. The AsX (X = Al or Ga) and XAs defects always induce metallicity of GaAs/AlAs superlattice, and GaAl and AlGa antisite defects have slight effects on the electronic structure. For GaAs/AlAs superlattice with the interstitial or vacancy defects, significant reduction of band gap or induced metallicity is found. Further calculations show that the interstitial and vacancy defects reduce the electron mobility significantly, while the antisite defects have relatively smaller influences. The results advance the understanding of the radiation damage effects of the GaAs/AlAs superlattice, which thus provide guidance for designing highly stable and durable semiconductor superlattice based electronic and optoelectronics for extreme environment applications.
关键词： Point defect,Electrical properties,GaAs/AlAs superlattice,Hybrid density functional theory
更新于2025-09-04 15:30:14
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Intermixed Superlattices
摘要： The enhancement of stimulated Raman scattering (SRS) with a GaAs/AlAs intermixed superlattice that works as a χ (3)-quasi-phase-matched structure is studied, where such Kerr-induced effects as four-wave mixing (FWM), self-phase-modulation (SPM), cross-phase-modulation (XPM), and two-photon absorption (TPA) are included. In particular, the efficiency of anti-Stokes generation is enhanced here; anti-Stokes generation inherently has an extremely small efficiency due to a phase mismatch in the interaction of the pump, Stokes, and anti-Stokes waves (while the efficiency of Stokes generation is sufficiently large because of no such phase mismatch). The superlattice enhances the anti-Stokes efficiency up to the order of 103 when compared with that without the superlattice, particularly at a small pump intensity. In this enhancement, it is seen that there is an efficiency boost via simultaneous FWM. In this situation, it is shown how much SPM and XPM degrade the efficiency enhancement. Furthermore, an optimal superlattice length is identified that provides the highest efficiency. The degradation of the efficiency at the optimized length due to TPA is also analyzed. Finally, to gain more anti-Stokes efficiency (or control the sizes of the Stokes and anti-Stokes efficiencies), a photonic-band-gap cavity structure is proposed.
关键词： anti-Stokes generation,nonlinear optics,quasi-phase-matching,GaAs/AlAs superlattice,stimulated Raman scattering
更新于2025-09-04 15:30:14