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RISS 인기검색어
- 검색키워드
- 주제어 : Confined phonon (검색결과 5 건)
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Bau Nguyen Quang,Quynh Nguyen Thi Lam,Ba Cao Thi Vi,Hung Le Thai 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.12
Photo-stimulated quantum thermo-magnetoelectric effects in doped two-dimensional semiconductor superlattices, including the photo-stimulated quantum Ettingshausen effect and the photo-stimulated quantum Peltier effect, have been theoretically studied by using the quantum kinetic equation method. In this work, we assume that the electron-confined acoustic phonon scattering is essential. Moreover, the presence of the laser radiation (LR) is also taken into account to determine the influence of confined phonons on the aforementioned effects. We have defined the analytical expressions for the kinetic tensors and the Ettingshausen and the Peltier coefficients, presented the numerically calculated the theoretical results for the GaAs:Si/GaAs:Be doped semiconductor superlattice and compared them with these for the case of an unconfined acoustic phonon. The results obtained indicated that the formulas for the kinetic tensors, the Ettingshausen coefficient (EC) and the Peltier coefficient (PC) contain the quantum number m specifying the confinement of a phonon and approach the results for an unconfined phonon as m goes to zero. We found that the kinetic tensors, the EC and the PC oscillate with changing magnetic field and that the confinement of a phonon causes a shift of the peaks in these oscillations to lower energy. The dependences of both EC and PC on the temperature were found to be nonlinear. Moreover, all the coefficients level off when the temperature was less than 4.5 K or greater than 5.5 K. The EC also depended on the doping concentration in a nonlinear way and reaches a positive constant value when the semiconductor superlattice was doped with a high concentration. Most of the numerical results showed that the magnitude of the tensors, the EC as well as the PC, within a confined acoustic phonon varie significantly in comparison with the unconfined phonon case. This means that the confinement of the phonon affects the thermo-magnetoelectric effect quantitatively and qualitatively. These results contribute to completing the theory of the thermo-magnetoelectric effects in the low-dimensional semiconductor systems.
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Tran Cong Phong,Le Thi Thu Phuong,Huynh Vinh Phuc,Pham Tuan Vinh 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.2
We investigate the influence of phonon confinement on the optically-detected electrophonon resonance (ODEPR) effect and ODEPR linewidth in rectangular quantum wires (RQW). The ODEPR conditions as functions of the wire’s size and the photon energy are also obtained. The splittings of ODEPR peaks caused by the confined phonon are discussed. The numerical result for a specific RQW shows that in the two cases of confined and bulk phonons, the linewidth decreases with increasing wire size and increases with increasing temperature. Furthermore, in the small range of the wire’s size (<i>L</i> ≤ 40 nm), phonon confinement plays an important role and cannot be neglected in reaching the ODEPR linewidth.
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Raman Spectroscopy of Lithographically Patterned Graphene Nanoribbons
Ryu, Sunmin,Maultzsch, Janina,Han, Melinda Y.,Kim, Philip,Brus, Louis E. American Chemical Society 2011 ACS NANO Vol.5 No.5
<P>Nanometer-scale graphene objects are attracting much research interest because of newly emerging properties originating from quantum confinement effects. We present Raman spectroscopy studies of graphene nanoribbons (GNRs), which are known to have nonzero electronic bandgap. GNRs of width ranging from 15 to 100 nm have been prepared by e-beam lithographic patterning of mechanically exfoliated graphene followed by oxygen plasma etching. Raman spectra of narrow GNRs can be characterized by an upshifted G band and a prominent disorder-related D band originating from scattering at the ribbon edges. The D-to-G band intensity ratio generally increases with decreasing ribbon width. However, its decrease in width of <25 nm, partly attributed to amorphization at the edges, provides a valuable experimental estimate on D mode relaxation length of <5 nm. The upshift in the G band of the narrowest GNRs can be attributed to confinement effect or chemical doping by functional groups on the GNR edges. Notably, GNRs are much more susceptible to photothermal effects resulting in reversible hole doping caused by atmospheric oxygen than bulk graphene sheets. Finally we show that the 2D band is still a reliable marker in determining the number of layers of GNRs despite its significant broadening for very narrow GNRs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2011/ancac3.2011.5.issue-5/nn200799y/production/images/medium/nn-2011-00799y_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn200799y'>ACS Electronic Supporting Info</A></P>
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Thickness fluctuation relations in carrier dynamics of CdTe/ZnTe quantum dots
Man, M.T.,Kim, T.W.,Lee, H.S. Elsevier [etc.] 2016 Journal of luminescence Vol.178 No.-
<P>We investigated the influence of thickness fluctuations on the carrier dynamics of CdTe/ZnTe quantum dots (QDs). The temperature dependence of both the red-shift in the band-edge transition energy and broadening of the emission line were evaluated using different models. We showed that the quantum confinement effect and thermal escape of the QDs can be extended to significantly higher temperatures. These results were confirmed by using the discrete recombination model to investigate localized and delocalized states. Taking place into the reducing fluctuations of QDs that the thermally activated transition energies and the carrier scattering via phonons are enhanced. (C) 2016 Elsevier B.V. All rights reserved.</P>
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