a-Si:H-based triple-junction cells prepared at i-layer deposition rates of 10 a/s using a 70 MHz PECVD technique

Using a 70 MHz VHF PECVD technique to prepare all of the i-layers at deposition rates near 10 Å/s, a-Si:H/a-SiGe:H/a-SiGe:H triple-junction cells have been fabricated and initial active area AM1.5 efficiencies of 11% (total area efficiencies of 10-10.3%) have been achieved. After 700 hrs, of light soaking of one sun light soaking, the cell efficiencies degrade to 9.6% with a percentage of degradation of 10-14%, a percentage typical of what is obtained for high efficiency triple-junction cells prepared using i-layer deposition rates near 1 Å/s. A major challenge toward further improving the efficiencies is the fabrication of a-SiGe:H i-layers at 10 a/s with the quality of those made using the standard 13.56 MHz, 1 Å/s method. Deposition conditions that lead to less polyhydride formation during a-SiGe:H growth would likely lead to improved performance for the triple-junction cells