2007 Fiscal Year Final Research Report Summary
First-principles nonlocal optical response theory of semiconductor surfaces and interfaces with vertical polarization
| Project/Area Number |
17540291
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Condensed matter physics I
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| Research Institution | Chiba University |
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Principal Investigator |
NAKAYAMA Takashi Chiba University, Graduate School of Science, Professor (70189075)
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| Co-Investigator(Kenkyū-buntansha) |
ONO Yuuki Frontier Science Center, 先進科学研究教育センター, Doctor Researcher (50423083)
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| Project Period (FY) |
2005 – 2007
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| Keywords | first-principles calculation / optical response function / nonlocal response / surface and interface / interface polarization / amino acid / dislocation / charge transfer dynamics |
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| Research Abstract |
We have developed the first-principles calculation methods of electronic structures and nonlocal response functions of vertically polarized surfaces and interfaces, and clarified physical properties induced by the vertical polarization as follows. 1. Theory of surface/interface optical response spectra; It was generally shown that, reflecting the localization of surface and interface electronic states, the vertical polarization renormalizes to suppress the absorption spectrum magnitude, by a few ten percents. In addition, the vertical polarization often eliminates the spectral peaks of adsorbed molecules through the anisotropy of molecule alignment. 2.Opto-ionization of bio-amino acids at semiconductor interfaces; Amino acids are classified into two groups from electronic viewpoints and are optically ionized at semiconductor interfaces due to the hybridization of electronic states. Moreover, the acids-substrate junctions are stable even when ionized. 3. Interface and dislocation-induced electron carriers; We have shown that the metal interfaces and dislocations promote N-atom-originated resonance states in the conduction bands of InN films and produce electron carriers, in agreement with the experiments. However, such anion states become deep levels in the band gap, thus never producing carriers in Si, GaAs, and GaN. 4. Generalized theory of interface polarization and charge-transfer dynamics; We have constructed the generalized charge-neutrality theory of hybridization-induced interface polarization, which well explains the observed unusual polarization behavior at metal/high-k interfaces. Moreover, the dynamical behavior of charge transfer, such as relaxation and quantum oscillation, is theoretically clarified by analyzing the transient current at molecule-electrode interfaces and the current-induced quantum friction of molecule vibration.
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Research Products
(66 results)
