Improving optoelectrical properties of porous silicon by the combination of samarium pore-filling and post-annealing treatment

In this paper, we highlight the beneficial effect of the combination of samarium (Sm) pore-filling and annealing treatment of porous silicon (pSi) microstructure. The Sm(III) thin layer was imaged by scanning electron microscopy. The changes of surface chemical composition and spatial distribution of elements in the Sm/pSi microstructure were inspected using Fourier-transform infrared and X-ray diffraction, respectively. For the optical characterizations, a substantial increase in the photoluminescence intensity was observed after the surface treatment especially at 500 °C. In addition a considerable decrease of the total reflectivity from 15 to 5% was obtained. For the electrical characterizations, the minority carrier lifetime (τ_eff) of pSi was significantly enhanced from 2 to 76 μs due to the formation of a stable Sm(III) passivating layer and the saturation of dangling bands. The electrical parameters of solar cells under elimination extracted from I–V characteristics shows an enhancement in the efficiency (η) from 8.1 to 11%.