Characterization of amorphous materials for solar cell applications

The important climate change humanity is currently facing can partly be limited by producing low-carbon electricity. In that contest, harvesting the solar energy through solar cells is key. The company Maana Electric targets to create solar cells based on the silicon heterojunction design. This design implies the deposition of thin amorphous semiconducting layers. The purpose of this work is to investigate the optoelectronic properties of the hydrogenated amorphous silicon (a-Si:H) and hydrogenated amorphous silicon carbide (a-SiC:H) films deposited by Maana Electric. The fine-tuning of these properties by laser annealing is an interesting tool for the maximization of the solar cell efficiency. This master thesis starts with the analysis of the amorphous coatings deposited and laser annealed by Maana Electric. The layer homogeneity is first discussed using optical microscopy. The carbon, silicon, and oxygen concentration in the films are then retrieved using X-ray photoelectron spectroscopy. The optical bandgap is subsequently derived from spectrophotometry. The microstructure parameter and hydrogen content are finally derived using Raman spectroscopy. Afterwards, the interdependence of the optical bandgap, the microstructure parameter, and the hydrogen content is discussed. In the purpose of comparison with laser annealing, the properties of oven annealed amorphous coatings are investigated for different annealing temperatures. In particular, the optical bandgap, microstructure parameter, and hydrogen content are gathered following the same procedure as for the as-deposited and laser annealed coatings. Their interdependence is finally discussed. However, the low number of experimental points prevents the identification of a reliable trend.