Dielectric Bragg back reflecting mirror in a-Si:H / c-Si heterostructure solar cell

In this work we present the design and fabrication of a Bragg reflector, formed on the rear side of an amorphous/crystalline silicon (a-Si/c-Si) n-a-Si/i-a-Si/p-c-Si heterostructure solar cell, in order to obtain an enhancement of the optical confinement of the near-infrared wavelength. The mirror has been grown alternating several couples of amorphous silicon/silicon nitride films whose thicknesses have been optimized, to maximize the reflectance inward the c-Si wafer, using an optical simulator. The cell back contact has been ensured by an Al diffusion into the c-Si wafer promoted by Nd-YAG pulsed laser. The front cell contact has been enhanced by a chromium silicide CrSi formed on top of the n-a-Si layer. A V_oc of 681 mV and 94% of internal quantum efficiency at 1000 nm have been achieved.