Electrical conduction of Si/indium tin oxide/Si junctions fabricated by surface activated bonding

The electrical properties of n+-Si//indium tin oxide (ITO)/n+-Si, n+-Si//ITO/p+-Si, and p+-Si//ITO/n+-Si junctions fabricated by surface activated bonding (SAB) were investigated. The current–voltage (I–V) characteristics of n+-Si//ITO/n+-Si, n+-Si//ITO/p+-Si, and p+-Si//ITO/n+-Si junctions showed excellent linear properties. The interface resistances of n+-Si//ITO/n+-Si, n+-Si//ITO/p+-Si, and p+-Si//ITO/n+-Si junctions were found to be 0.030, 0.025, and 0.029 Ω·cm2, respectively, which are lower than required for concentrator photovoltaics. The interface resistances of all the junctions increased with increasing annealing temperature. The degradation of the interface resistance is lower in n+-Si//ITO/n+-Si junctions than in n+-Si//ITO/p+-Si and p+-Si//ITO/n+-Si junctions, when the annealing temperature is higher than 100 °C. These results demonstrate that the ITO thin film as an intermediate layer has high potential application for the connection of subcells in the fabrication of tandem solar cells.