1. Full name: Nguyen Thi Nguyet Anh 2. Sex: female
3. Date of birth: 11/10/1988 4. Place of birth: Nam Dinh
5. Admission decision number: No. 2556/QĐ-ĐHKHTN 26/07/2017 of the principal VNU University of Science.
6. Changes in academic process: Decision no 318/QĐ –ĐHKHTN 01/02/2021 and decision no 231/QĐ- ĐHKHTN 27/01/2022.
7. Official thesis title: The influence of quantization caused by size reduction on the Ettingshausen effect and the Peltier effect in one - dimensional system.
8. Major: Theoretical Physics and Mathematical Physics 9. Code: 9440130.01
10. Supervisors: Assoc. Prof. Luong Van Tung
Prof. Nguyen Quang Bau
11. Summary of the new findings of the thesis
For the first time, the quantum kinetic equation for the electron distribution function in cylindrical quantum wires (CQW) and rectangular quantum wires (RQW) was established in the presence of a strong electromagnetic wave, a direct current (DC) magnetic field, strong magnetic field, and the confinement of electrons and phonons.
Finding the analytical expressions for the kinetic tensors, the Ettingshausen coefficient (EC), and the Peltier coefficient (PC) in one - dimensional semiconductor systems. These quantities all depend on the parameters characteristic of the external field (amplitude, frequency of electromagnetic waves, constant electric and magnetic fields), material structure parameters (wire radius, wire length), the temperatures of the system especially the quantum numbers that characterize the confinement of electrons and phonons.
The obtained analytical results show that the size quantization reduction in CQW and RQW strongly affects EC and PC, and have more different compared to the bulk semiconductors, in the two dimensions (2D) (doped superlattices and quantum well). The reason is the difference between the quantum m1, and m2 which characterize phonon confinement, and the quantum numbers N, n which characterize electron confinement. And the results show that when goes to 0 and the electron form factor returns to the expression as in the unconfined phonon case, the obtained result will return to the case of the unconfined phonons.
The analytical results are estimated, graphed, and discussed for CQW of GaAs/ AlGaAs and GaAs, and RQW of GaAs models. The obtained results are in good agreement with both quantitative and qualitative compared to the experimental and theoretical results of the different authors (calculations in 1D do not consider the confinement of phonon and 2D). The results indicate that the confined phonon has changed significantly the magnitude of the EC and the PC in 1D compared to the unconfined phonons case. Additionally, confined optical phonons make more resonance peaks appear, and as the materials have small sizes, the kinetic effects occur more clearly under the influence of electron and phonon confinement.
The thesis indicated the magneto – phonon resonance (MPR) condition in the 1D system in the presence of a strong magnetic field, a dc electric field, a strong electromagnetic wave and including confined optical phonon. The MPR condition contributes to determine the posistion, the high and the shifts of the resonance peaks, which obtained when examining the dependence of the EC and PC on the external fields. Besides, confined acoustic phonons gives rise to Shubnikov-de Haas (SdH) type oscillations when investigating low - temperature matter systems.
The thesis also contributes to confirming the effectiveness and correctness of the quantum kinetic equation method when investigating the kinetic properties in low - dimensional semiconductor systems. In addition, the thesis’s results are the basis for explaining the properties of the 1D semiconductor system under the influence of an external field when considering two scattering mechanisms: confined electrons - confined acoustic phonons, and confined electrons - confined optical phonons.
12. Practical applicability, if any:
The results of the thesis will contribute to the direction of the technology of manufacturing electronic components on the basis of low - dimensional semiconductors and its application in today's ultra-small, innovative, and versatile electronic devices.
13. Further research directions, if any:
Quantum magnetic – thermal – electrical effects in asymmetric low - dimensional semiconductor systems.
14. Thesis-related publications:
[1]. Hoang Van Ngoc, Nguyen Thi Nguyet Anh*, Tang Thi Dien, Nguyen Quang Bau, Nguyen Vu Nhan (2021), “The Influence of confined acoustic phonon on the quantum Ettingshausen effect in cylindrical quantum wire with an infinite potential in presence of strong electromagnetic wave”, J. Phys: Conf. Ser. 1932, 012008. (Scopus)
[2]. Hoang Van Ngoc, Nguyen Thi Nguyet Anh*, Tang Thi Dien, Nguyen Quang Bau (2022), “Cylindrical quantum wires: the Quantum photo-stimulated Peltier effect under the influence of confined acoustic phonons”, J. Phys: Conf. Ser. 2269, 012007. (Scopus)
[3]. Nguyen Quang Bau*, Tang Thi Dien, Nguyen Thi Nguyet Anh, Nguyen Dinh Nam, Do Tuan Long. (2022), “Influence of confined optical phonons on the Photo -stimulated thermo-magnetoelectric effect in cylindrical quantum wires”, Phys. Rev. B. 644, 414220. (ISI)
[4]. Nguyen Thi Nguyet Anh*, Tang Thi Dien, Cao Thi Vi Ba, Hoang Van Ngoc. (2022), “The Photo-stimulated Peltier Effect in Rectangular Quantum Wires under the Influence of Confined Phonons”, VNU J. Sci.: Math. Phys. 38, pp. 11 - 16.
[5]. Nguyen Thi Nguyet Anh*, Luong Van Tung, Nguyen Quang Bau, Tang Thi Dien. (2023), “Effect of confined optical phonons on photo-stimulated Ettingshausen effect in rectangular quantum wires with a perpendicular magnetic field”, VNU J. Sci.: Math. Phys. 39, pp. 27-33.
[6]. Tang Thi Dien, Cao Thi Vi Ba, Nguyen Quang Bau* and Nguyen Thi Nguyet Anh (2023), “Calculation of parallel Peltier coefficient in rectangular quantum wires under the influence of confined optical phonons and electromagnetic waves by using quantum kinetic equation”, J. Korean Phys. Soc, pp 1-9, https://doi.org/10.1007/s40042-023-00781-2. (ISI)
