Abstract
The electronic properties of zincblende ZnSe/Si core-shell nanowires (NWs) with a diameter of 1.1–2.8 nm are calculated by means of the first principle calculation. Band gaps of both ZnSe-core/Si-shell and Si-core/ZnSe-shell NWs are much smaller than those of pure ZnSe or Si NWs. Band alignment analysis reveals that the small band gaps of ZnSe/Si core-shell NWs are caused by the interface state. Fixing the ZnSe core size and enlarging the Si shell would turn the NWs from intrinsic to p-type, then to metallic. However, Fixing the Si core and enlarging the ZnSe shell would not change the band gap significantly. The partial charge distribution diagram shows that the conduction band maximum (CBM) is confined in Si, while the valence band maximum (VBM) is mainly distributed around the interface. Our findings also show that the band gap and conductivity type of ZnSe/Si core-shell NWs can be tuned by the concentration and diameter of the core-shell material, respectively.
Highlights
Semiconductor nanowires (NWs) have received extensive attention for their unique one-dimensional structure and the progress in the preparation method [1]
In this paper, we present the electronic properties of Zinc selenide (ZnSe) NWs, nanotubes (NTs) and ZnSe/Si core-shell NWs by means of the first principles calculation based on density functional theory (DFT) [24,25]
The results show that ZnSe NTs have larger band gaps than those of ZnSe NWs of the same diameter, due to their stronger quantum confinement effect
Summary
Semiconductor nanowires (NWs) have received extensive attention for their unique one-dimensional structure and the progress in the preparation method [1]. The past decade has witnessed their application in various electronic and photonic devices, such as diodes [2], lasers [3], field effect transistors [4], biological sensors [5] and integrated logical calculators [6,7]. Among all kinds of NWs, core-shell NWs are prominent for their variation of composition in the radial direction [8]. Since NWs are well known for their ability to form heterostructures with large lattice mismatch, while avoiding creating dislocations, core-shell NWs are hoped to be the carrier of heterostructures that cannot be grown epitaxially in planar form [9]. Silicon (Si) is the basic material in the semiconductor industry, and mature methods have been established to fabricate Si-based electronics.
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