Capacitance study of inversion at the amorphous-crystalline interface of n-type silicon heterojunction solar cells
Abstract
We use capacitance techniques to directly measure the Fermi level at the crystalline/amorphous interface in n-type silicon heterojunction solar cells. The hole density calculated from the Fermi level position and the inferred band-bending picture show strong inversion of (n)crystalline silicon at the interface at equilibrium. Bias dependent experiments show that the Fermi level is not pinned at the interface. Instead, it moves farther from and closer to the crystalline silicon valence band under a reverse and forward bias, respectively. Under a forward bias or illumination, the Fermi level at the interface moves closer to the crystalline silicon valence band thus increases the excess hole density and band bending at the interface. This band bending further removes majority electrons away from the interface leading to lower interface recombination and higher open-circuit voltage.
- Publication:
-
Journal of Applied Physics
- Pub Date:
- December 2011
- DOI:
- 10.1063/1.3663433
- Bibcode:
- 2011JAP...110k4502L
- Keywords:
-
- amorphous semiconductors;
- capacitance;
- electron-hole recombination;
- elemental semiconductors;
- Fermi level;
- hole density;
- semiconductor heterojunctions;
- silicon;
- solar cells;
- valence bands;
- 88.40.jj;
- 88.40.jp