層狀系統於外場下的電子性質

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國立成功大學「邁向頂尖大學計畫」

　　延攬優秀人才工作報告表

NCKU’s “Aim for the Top University Project”

Work Report Form for Distinguished Scholars

□續聘continuation of employment ■離職resignation

100 年 7 月 13 日更新

受聘者姓名 Name of the Employee

陳思超 ■男

Male Female

聘期 Period of Employment

from 2011 年(y) 4 月(m) 1 日(d)

to 2012 年(y) 3 月 (m) 31 日 (d)

研究或教學或科技研發與管理計畫名稱 The project title of research,

teaching, technology development and management

層狀系統於外場下的電子性質 ^{計畫主持人}

（申請單位主管）

Project Investigator (Head of Department/Center)

林明發

補助延聘編號

Grant Number HUA 100 - 3 - 2 - 146

一、研究、教學、科技研發與管理工作全程經過概述。（由受聘人填寫）

Please summarize the entire research, teaching, or science and technology R&D and management work process (To be completed by the employee)

過去半年多的時間內(2011.4~2011.12)，研究主題著重於碳相關系統的計算。

主要利用緊束模型精確解出能帶及波函數分佈，再進一步探討其他的物理特性，且透過複雜的數值技巧來計算及分析。具體的研究結果條列式說明如下：

一、國際期刊論文：

(1) Magneto-Optical Properties of Armchair Nanographene Ribbons under Spatially Modulated Electric Field

Szu-Chao Chen, Chih-Wei Chiu, and Ming-Fa Lin,

The spatially modulated electric field is used to tune the magneto-optical properties of an armchair nanographene ribbon. The band structure and optical absorption spectrum under the perpendicular magnetic field and the spatially modulated electric field are calculated through the tight-binding model and the gradient approximation. The

quasi-Landau levels are greatly affected by the periodic potential such as the modulation of the energy dispersion, the creation of the extra band-edge states, and the alteration of the Landau wave functions. The modulation ability of the electric field grows with the increase of the electric field strength or the decrease of the periodic length. The change of the electronic properties is directly reflected in the optical absorption spectra. The number, the shape, the intensity, and the position of the absorption peaks are altered. The selection rule of the optical excitations between the quasi-Landau levels is destroyed under the influence of the modulated electric field. The predicted results can be directly verified by optical measurements.

已發表於Jpn. J. Appl. Phys.50(2011) 01AF14 (ISI)

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(2) Tuning the electronic properties of monolayer graphene by the periodic aligned graphene nanoribbons

C.H. Lee, S.C. Chen, W.S. Su, R.B. Chen*, M.F. Lin**

The 2pz tight-binding model has been used to investigate the electronic properties of ribbon–graphene hybrid systems. This system is constructed by zigzag graphene nanoribbons aligned periodically on monolayer graphene. It was found that for such systems the electronic properties would be strongly influenced by the geometric structure of graphene nanoribbons, such as the width and the period of the ribbons. In addition, the stacking arrangement between graphene nanoribbons and monolayer graphene also plays a dominant role in determining the band structures in the low-energy region. These geometric structure effects can be well understood through the density of state

calculations. Such hybrid structures lead to interesting novel features, dissimilar from those of single layer graphene, and could serve as a platform for the studies of device applications.

已發表於Synthetic Metals 161 (2011) 489–495. (ISI)

(3) Low-energy electronic structures of nanotube–nanoribbon hybrid systems C.H. Lee, S.C. Chen, C.K. Yang, W.S. Su,∗, M.F. Lin,∗

The electronic properties of a nanotube–nanoribbon hybrid system are investigated by the first-principles calculations. This hybrid system is constructed by a zigzag carbon nanotube and an armchair graphene nanoribbon. Its electronic structures strongly depend on the nanotube location and stacking configuration. The interactions between the two subsystems would break the state degeneracy, open subband spacings, and induce more band-edge states. The predicted results could be measured directly by the scanning tunneling spectroscopy.

已發表於Computer Physics Communications 182 68-70 2011. (ISI)

(4) Plasma Excitations in Graphene: Their Spectral Intensity and Temperature Dependence in Magnetic Field

Jhao-Ying Wu, Szu-Chao Chen, Oleksiy Roslyak, Godfrey Gumbs,*, and Ming-Fa Lin*

In this paper, we calculated the dielectric function, the loss function, the

magnetoplasmon dispersion relation and the temperature-induced transitions for

graphene in a uniform perpendicular magnetic field B. The calculations were performed using the Peierls tight-binding model to obtain the energy band structure and the

random-phase approximation to determine the collective plasma excitation spectrum.

The single-particle and collective excitations have been precisely identified based on the resonant peaks in the loss function. The critical wave vector at which plasmon damping

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takes place is clearly established. This critical wave vector depends on the magnetic field strength as well as the levels between which the transition takes place. The temperature effects were also investigated. At finite temperature, there are plasma resonances induced by the Fermi distribution function. Whether such plasmons exist is mainly determined by the field strength, temperature, and momentum. The inelastic light scattering

spectroscopies could be used to verify the magnetic field and temperature induced plasmons.

已發表於ACS Nano 5 1026-1032 (2011). (ISI)

(6) Electronic properties of bilayer AA-stacked zigzag nanographene ribbons

S.L. Chang, C.H. Tsai, W.S. Su, S.C. Chen*, M.F. Lin*

First-principles calculations within the generalized gradient approximation are employed to calculate the electronic properties of the bilayer AA-stacked zigzag nanographene ribbon. The AFM–AFM configuration (antiferromagnetic and antiferromagnetic configurations for the intralayer and interlayer spin arrangements, respectively) is

predicted to be the most stable system. The interlayer interactions alter the band structure such as the modulation of energy dispersions, the generation of new band-edge states, and the state degeneracy. The energy gap is inversely proportional to the ribbon width.

As compared with the monolayer zigzag nanographene ribbon, the density of states exhibits more asymmetric peaks, and some peaks at low energy are enhanced due to the state degeneracy. These predicted results can be identified by scanning tunneling

spectroscopy (STS) or the measurements of optical spectra.

已發表於 Diamond & related materials 20 (2011) 505-508

(7) The destruction of Landau levels in graphene nanoribbons by magnetic modulation

Jhao-Ying Wu, Szu-Chao Chen, and Ming-Fa Lin

The destruction of Landau levels of one-dimensional graphene nanoribbons in a

modulated magnetic field is investigated by the Peierls tight-binding model. The partial flat subbands are transformed into oscillating parabolic subbands, and the dispersion is very sensitive to the modulation period and the field phase. The density of states, which reflects the main features of the energy bands, reveals peak spectra that are controllable through adjusting parameters of the modulated magnetic field. These spectra promise possible applications in electronic devices.

已發表於 JAP 110 063718 (2011)

(8) Curvature e_ects on magnetoelectronic properties of nanographene ribbons

C. Y. Lin, S. C. Chen^*, J. Y. Wu^*, M. F. Lin^*

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Magnetoelectronic properties of curved nanographene ribbons are investigated through the Peierls tight-binding model. Those properties are strongly a_ected by an e_ectively non-uniform magnetic _eld and the _nite-size e_ect. The curvature con-verts

quasi-Landau levels into oscillating parabolic energy bands with several band-edge states. Such extra states induce asymmetric prominent peaks in the density of states. The number, height, spacing and frequency of those peaks depend strongly on the _eld

strength and the central angle. Moreover, the spatial symmetry of the Landau wave

function is broken. The simple proportionality relationship between the wave function on the two sublattices A and B disappears, which implies that the essential physical

properties might be drastically changed. Nanographene ribbons are very di_erent from carbon nanotubes in electronic properties, mainly owing to the boundary conditions.

已投稿至 JPSJ (2012)

二、研究或教學或科技研發與管理成效評估（由計畫主持人或單位主管填寫）

Please evaluate the performance of research, teaching or science and technology R&D and management Work: (To be completed by Project Investigator or Head of Department/Center)

(1)是否達到延攬預期目標？

Has the expected goal of recruitment been achieved?

(2)研究或教學或科技研發與管理的方法、專業知識及進度如何？良好

What are the methods, professional knowledge, and progress of the research, teaching, or R&D and management work?

(3)受延攬人之研究或教學或科技研發與管理成果對該計畫(或貴單位)助益如何？良好

How have the research, teaching, or R&D and management results of the employed person given benefit to the project (or your unit)?

(4)受延攬人於補助期間對貴單位或國內相關學術科技領域助益如何？良好

How has the employed person, during his or her term of employment, benefited your unit or the relevant domestic academic field?

(5)具體工作績效或研究或教學或科技研發與管理成果：

Please describe the specific work performance, or the results of research, teaching, or R&D and management work:

陳思超博士於聘任期間主要研究奈米石墨帶在外加場下的電子和光學性質以及單層石墨的磁電子激發。部分研究成果已被發表在國際期刊(如上述著作) 。此外，尚有數篇論文在審查中。陳思超博士也協助指導博士班的學弟研究，已有明確的成果，正在撰寫準備要投稿的論文。陳思超博士工作認真，近一年來研究成果具體、豐碩，可謂超出延攬預期目標。

(6)是否續聘受聘人? Will you continue hiring the employed person? □續聘Yes ■不續聘No

※ 此報告表篇幅以三～四頁為原則。This report form should be limited to 3-4 pages in principle.

※ 此表格可上延攬優秀人才成果報告繳交說明網頁下載。

This report form can be downloaded in http://scholar.lib.ncku.edu.tw/explain/