Good Quality N (a-Si)-P+(Na-Si)-P (μC-Si) Tunnel Junction for Tandem Solar Cells

Abstract

A new tunnel-recombination junction model was proposed to increase the recombination of n/p junctions in tandem solar cells. According to the model, we fabricated a new tunnel junction with a nanostructured amorphous silicon p+(na-Si p+) layer inserted between the n layer and the p layer. To compare with the conventional method, we fabricated another tunnel junction with an amorphous p+(a-Si p+) insertion layer. Both devices were characterized by their dark current-voltage behavior (I-V), activation energy (Ea) and quantum efficiency (QE). The result shows that the tunnel junction with a na-Si p+insertion layer has higher recombination rates with higher density of defect states of about 2.7×1019cm-3, lower resistance with activation energy of 22meV. The tunnel junction with a na-Si p+insertion layer could be easily integrated into the tandem solar cell deposition process.