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ZnSe / Si heterojunction Nanowires

Author: ZhangHuiZuo
Tutor: XingHuaiZhong
School: Donghua University
Course: Plasma Physics
Keywords: First Principle ZnSe / Si Heterojunction Nanowires Electronic structure
CLC: TB383.1
Type: Master's thesis
Year: 2012
Downloads: 48
Quote: 0
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Abstract

Semiconductor heterojunction nanowire morphology due to its unique structure and excellent properties of different materials, nano-materials science has become one of the hotspots. In this paper, based on first-principles density functional theory plane-wave pseudopotential method, using CASTEP software research with different doping concentrations of ZnSe / Si heterostructure nanowires, at the theoretical level nanowires on structural stability and electronic properties research and exploration for the future development and application of nano-devices provides a good theoretical basis. First, the article constructed (110) direction ZnSe / Si heterojunction nanowire model surface dangling bond and containing hydrogen atoms with dangling bonds of the surface passivation doping concentration gradients in both cases the stability of nano-heterostructures sexual conduct research. Study found that after optimization heterojunction nanowire for all atoms in a surface reconstruction, especially with Si-doped ZnSe / Si nanowires lattice distortion is large, the outer surface of the hetero atoms junction outward relaxation by a big margin, while the inward relaxation atom at the center of a small range. Then, the nano heterojunctions were measured lattice constant, between the ZnSe and Si nearly 4% of the lattice constant mismatch, so to some extent, but deviated from Vegard's law as shown in a linear relationship is nonlinear. However, with the Si component content increases, the lattice constant heterojunction nanowire decreases the overall trend has not changed. Secondly, the binding energy is a measure of the stability of nanowires another important parameter. This comparative analysis of different doping concentrations of unsaturated and saturated surface dangling bond hydrogen atom in both cases the binding energy of nanowires, found that with the increase of the content of silicon component, nano heterogeneous system increases linearly with energy, material structure more stable. And, the use of a hydrogen atom a saturated surface dangling bonds ZnSe / Si heterojunction nanowire more easily synthesized. Then, the paper studies the effect of surface dangling bonds for ZnSe / Si heterojunction nanowire electronic characteristics found to contain nano-heterostructures dangling bonds exhibit metallic, while using hydrogen saturated surface dangling bonds can effectively eliminate suspension The surface state of the key characteristics of the electronic structure, the semiconductor material into nanowires. On the other hand, we have the impurity-doped silicon nanowires content changes on energy band structure of a detailed analysis, we found doped nanowire heterostructures for band structure has played an effective role in the modulation, in which pure silicon nanowires exhibit characteristics different from bulk silicon, into a direct band gap semiconductor, and the band broadband increased significantly. In particular, the impurity level of the band edge of the ZnSe / Si nanowire heterostructure in the N-type semiconductor and a P-type semiconductor conversion between. When the doping concentration is relatively low, the nanowires showing N-type semiconductor characteristics, and when the doping concentration is high, the nanowire is converted to P-type semiconductor. Conclusion For this groundbreaking nano-heterogeneous materials in the field of optical and electrical applications, providing an important basis. Finally, after completion of the work, based on the Ga, N-doped InSb sphalerite structure of the electronic structure of the system, the results show that incorporation of N or Ga alone, the band gap can not be opened, and found that with the N content The increase can be formed zero bandgap semiconductor InSbN, which for zero bandgap semiconductor materials research project to provide a certain reference value. The co-doped Ga and N, its band gap changed significantly.

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