Stark effect, polarizability, and electroabsorption in silicon nanocrystals

Kulakci, Mustafa
Turan, Raşit
Demonstrating the quantum-confined Stark effect (QCSE) in silicon nanocrystals (NCs) embedded in oxide has been rather elusive, unlike the other materials. Here, the recent experimental data from ion-implanted Si NCs is unambiguously explained within the context of QCSE using an atomistic pseudopotential theory. This further reveals that the majority of the Stark shift comes from the valence states which undergo a level crossing that leads to a nonmonotonic radiative recombination behavior with respect to the applied field. The polarizability of embedded Si NCs including the excitonic effects is extracted over a diameter range of 2.5-6.5 nm, which displays a cubic scaling, alpha=cD(NC)(3), with c=2.436x10(-11) C/(V m), where D-NC is the NC diameter. Finally, based on intraband electroabsorption analysis, it is predicted that p-doped Si NCs will show substantial voltage tunability, whereas n-doped samples should be almost insensitive. Given the fact that bulk silicon lacks the linear electro-optic effect as being a centrosymmetric crystal, this may offer a viable alternative for electrical modulation using p-doped Si NCs.


Stability analysis of graphene nanoribbons by molecular dynamics simulations
Dugan, N.; Erkoç, Şakir (Wiley, 2008-04-01)
In this work, stability of graphene nanoribbons are investigated using molecular dynamics. Simulations include heating armchair and zigzag-edged nanoribbons of widths varying between one and nine hexagonal rings until the bonds between carbon atoms start to break. Breaking temperatures and binding energies per atom for different widths are presented for both armchair and zigzag-edged cases. A nontrivial relation between stability and width is observed and discussed.
Forward and reverse bias current-voltage characteristics of Au/n-Si Schottky barrier diodes with and without SnO2 insulator layer
GÖKÇEN, MUHARREM; ALTINDAL, ŞEMSETTİN; Karaman, M.; Aydemir, U. (Elsevier BV, 2011-11-01)
The effects of interfacial insulator layer, interface states (N-ss) and series resistance (R-s) on the electrical characteristics of Au/n-Si structures have been investigated using forward and reverse bias current-voltage (I-V) characteristics at room temperature. Therefore, Au/n-Si Schottky barrier diodes (SBDs) were fabricated as SBDs with and without insulator SnO2 layer to explain the effect of insulator layer on main electrical parameters. The values of ideality factor (n), R-s and barrier height (Phi(...
Erkoç, Şakir (Wiley, 1990-09-01)
The structural stability and energetics of microclusters containing 3 to 7 atoms of f.c.c. metal elements are investigated. A recently developed empirical many‐body potential function (PEF) is used in the calculations, which comprises two‐ and threebody atomic interactions. The PEF satisfies both, bulk cohesive energy and stability condition. It is found that the energetically most stable structures of microclusters are in compact form.
Electronic structure of carbon nanotubes: AM1-RHF calculations
Erkoç, Şakir; Turker, L (Elsevier BV, 1999-07-01)
We have investigated the electronic structure of optimized open-ended single-wall carbon nanotubes with armchair and zigzag geometries. The calculations were performed using AM1-RHF semiempirical molecular orbital method. It has been found that the density of states of the zigzag model is more sensitive to the tube size than that of the armchair model.
Electrical characterization of vacuum-deposited n-CdS/p-CdTe heterojunction devices
Bayhan, H; Ercelebi, C (IOP Publishing, 1997-05-01)
The effects of post-deposition processes such as CdCl2 dip and/or annealing in air on the material and device properties of vacuum-evaporated Au-CdTe/CdS-TO heterojunction solar cells have been investigated. The CdCl2 dip followed by air annealing at 300 degrees C for 5 min improved the device efficiency significantly, resulting in decreased CdTe resistivity and enhanced grain size. The temperature-dependent current-voltage analysis indicated that above 280 K interface recombination dominates the current tr...
Citation Formats
C. BULUTAY, M. Kulakci, and R. Turan, “Stark effect, polarizability, and electroabsorption in silicon nanocrystals,” PHYSICAL REVIEW B, pp. 0–0, 2010, Accessed: 00, 2020. [Online]. Available: