Thermal Activation of Boron- and Phosphorus-Doped Amorphous Silicon and the Contribution to Improved Efficiency in Hydrogenated Amorphous Silicon Solar Cells

Hydrogenated amorphous silicon (a-Si:H) is an interesting candidate as an absorber material for solar cells. Despite the wealth of research to improve the efficiency of a-Si:H solar cells by improving either the material quality of the absorber layer or by means of light trapping approaches, efforts to improve the efficiency by means of doped layer manipulation are relatively rare. In this work, single-junction a-Si:H solar cells with improved efficiency due to thermal activation of doped layers via thermal annealing will be presented. Temperature-dependent dark conductivity measurements revealed that p- and n-type doped a-Si:H materials show different equilibrium temperatures. External quantum efficiency at different annealing temperatures revealed that front surface collection probability was improved with the activation of a p layer, after which the collection probability of the back surface was improved with the activation of an n layer.