Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7923323 | Materials Chemistry and Physics | 2014 | 5 Pages |
Abstract
Electron and Li-ion transport at the n-ZnO/p-aSi (amorphous Si) heterojunction interface is analyzed for the initial charging conditions of a secondary battery anode. The ohmic and diode-type current-voltage characteristics of the junction are investigated for varying doping levels of aSi and ZnO layers. The interface potential barrier impacts the electrons supply to control the Li + ZnO â Li2O + LixZn reaction. The interface electric field could exceed â¼105 V cmâ1 and draws in Li ions from zinc oxide into the silicon layer. Relatively low-level doping (â¼1018 cmâ3) of the semiconductors is preferred for the optimum draw-in effect. During the initial charging, when the Li content in ZnO (as substitution LiZn acceptors) does not exceed the solubility level (â¼1019 cmâ3), the overall doping maintains the n-type, and the interface electric field continues to draw in Li ions towards silicon. Under further increase of Li content at interstitials, the layer conductivity is converted, and the heterojunction becomes nâ-n-p (or even p-n-p) type. During the subsequent transport of Li ions, the interface potential barrier diminishes and vanishes, and the current-voltage characteristics become ohmic. The importance of doping level control for both the materials is emphasized. The results are applicable for interface engineering in LIB anodes.
Keywords
Related Topics
Physical Sciences and Engineering
Materials Science
Electronic, Optical and Magnetic Materials
Authors
Joong Kee Lee, Aliaksandr A. Khodin,