DSpace Collection:
http://repository.vnu.edu.vn/handle/VNU_123/353
2018-03-16T16:44:50ZThe Photon-Drag Effect in Cylindrical Quantum Wire with an Infinite Potential for the Case of Electrons – Acoustic Phonon Scattering
http://repository.vnu.edu.vn/handle/VNU_123/61026
Title: The Photon-Drag Effect in Cylindrical Quantum Wire with an Infinite Potential for the Case of Electrons – Acoustic Phonon Scattering
Authors: Hoang, Van Ngoc; Nguyen, Vu Nhan; Dinh, Quoc Vuong
Abstract: The photon - drag effect with electrons – acoustic phonon scattering in cylindrical quantum wire with an infinite potential is studied. With the appearance of the linearly polarized electromagnetic wave, the laser radiation field and the dc electric field, analytic expressions for the density of the direct current are calculated by the quantum kinetic equation. The dependence of the direct current density on the frequency of the laser radiation field, the frequency of the linearly polarized electromagnetic wave and the temperature of the system is obtained. The analytic expressions are numerically evaluated and plotted for a specific quantum wire, GaAs/AlGaAs. The difference of the density of the direct current in quantum wires from quantum well and bulk semiconductor is due to potential barrier and characteristic parameters of system. These results are for every temperature and are new results.
Description: p. 80-862017-01-01T00:00:00ZEpitaxial-like growth of solution-processed PbZr0.4Ti0.6O3 thin film on single-crystal Nb-doped SrTiO3 substrate
http://repository.vnu.edu.vn/handle/VNU_123/61025
Title: Epitaxial-like growth of solution-processed PbZr0.4Ti0.6O3 thin film on single-crystal Nb-doped SrTiO3 substrate
Authors: Hoang, Ha; Bui, Nguyen Quoc Trinh
Abstract: PbZr0.4Ti0.6O3 (PZT) thin films have been conventionally fabricated on traditional silicon substrates with a platinum bottom electrode; however, as a consequence of unit cell mismatch, the films are difficult to form as an epitaxial-like growth. Hence, PZT films deposited on single-crystal niobium doped SrTiO3(111) substrates (Nb:STO) are promising to solve this issue thanks to the similar perovskite structure between PZT and STO. Essentially, Nb:STO material is a conductor, playing a part in both bottom electrode and epitaxial substrate. In this work, 200-nm-thick PZT films were successfully fabricated on Nb:STO substrates by a solution process. One obtained that PZT(111) peak started to appear on the Nb:STO substrate at a low annealing temperature of 450oC. Also, scanning electron microscopy observation shows smooth and homogeneous surface of PZT films on Nb:STO substrate with no grain boundary, which evidences for epitaxial-like growth of PZT thin films. Remnant polarization of 6 ÂµC/cm2 and leakage current of 8Ã—10-8 A were obtained at applied voltage of 5 V.
Description: p. 36-442017-01-01T00:00:00ZCalculation of the Ettingshausen coefficient in a Rectangular quantum wire with an infinite potential in the presence of an Electromagnetic wave (the electron - optical phonon interaction )
http://repository.vnu.edu.vn/handle/VNU_123/61023
Title: Calculation of the Ettingshausen coefficient in a Rectangular quantum wire with an infinite potential in the presence of an Electromagnetic wave (the electron - optical phonon interaction )
Authors: Cao, Thi Vi Ba; Tran, Hai Hung; Doan, Minh Quang; Nguyen, Quang Bau
Abstract: The Ettingshausen coefficient (EC) in a Rectangular quantum wire with an infinite potential (RQWIP)in the presence of an Electromagnetic wave (EMW) is calculated by using a quantum kinetic equation for electrons. Considering the case of the electron - optical phonon interaction, we have found the expressions of the kinetic tensors . From the kinetic tensors, we have also obtained the analytical expression of the EC in the RQWIP in the presence of EMW as function of the frequency and the intensity of the EMW, of the temperature of system, of the magnetic field and of the characteristic parameters of RQWIP. The theoretical results for the EC are numerically evaluated, plotted and discussed for a specific RQWIP GaAs/GaAsAL. We also compared received EC with those for normal bulk semiconductors and quamtum wells to show the difference. The Ettingshausen effect in a RQWIP in the presence of an EMW is newly developed.
Description: p. 17-232017-01-01T00:00:00ZInvestigation of Magneto-phonon Resonance in Graphene Monolayers
http://repository.vnu.edu.vn/handle/VNU_123/61019
Title: Investigation of Magneto-phonon Resonance in Graphene Monolayers
Authors: Le, Thi Thu Phuong; Tran, Thi My Duyen; Vo, Thanh Lam; Bui, Dinh Hoi
Abstract: In this work, utilising the linear response theory we calculate the magneto conductivity (MC) in graphene monolayers, subjected to a static perpendicular magnetic field. The interaction of Dirac fermions with optical phonon via deformation potential is taken into account at high temperature. The dependence of the MC on the magnetic field shows resonant peaks that describe transitions of electrons between Landau levels via the resonant scattering with optical phonons. The effect of temperature on the MC is also obtained and discussed.
Description: p. 45-562017-01-01T00:00:00Z