The role of volume deficiencies in hydrogenated germanium thin films deposited by PECVD for multijunction solar cell fabrication
Paula Perez-Rodriguez (TU Delft - Electrical Engineering, Mathematics and Computer Science)
Devansh Sharma (Student TU Delft)
Shubham Litke (Student TU Delft)
Arno H.M. Smets (TU Delft - Electrical Engineering, Mathematics and Computer Science)
More Info
expand_more
Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons.
Abstract
Multijunction devices are an effective way to increase the efficiency of solar cell. However, currently only expensive III-V technologies utilize the infrared part of the solar spectrum. To tackle this issue, this work explores the material properties of thin film amorphous hydrogenated germanium deposited by PECVD. It was found that high H2 dilution rates, deposition temperatures of 275 °C, pressures of 3 to 4 mbar and a power density around 0.20 W/m2 can achieve films with bandgaps of around 0.9 eV and activation energies above 450 meV, suggesting dense films with intrinsic behaviour. Regarding the mechanisms governing this behaviour, the results suggest that the performance of a-Ge:H is predominantly determined by mid-gap states, which are related to the high mobility of H during deposition within the a-Ge:H matrix. When small amounts of Si are introduced, the H atoms are fixed to the Si, reducing the defect density in the material.
help_outline