Research On Preparation And Properties Of Hit Solar Cell Materials

HIT solar cells have become a hot research topic due to its low cost, high efficiency, good stability and suitability for large area production. However, in order to meet the large demand of mass production and to achieve more efficient and cheaper HIT cells, not only a good interface passivation effect is required, but also the surface light reflectivity, optical absorption coefficient of amorphous silicon emitter, resistivity of transparent conductive film and the cost of the substrate material as well are all needed to be improved.In this paper, polycrystalline silicon substrate texturing treatment and the preparation and properties of intrinsic and doped amorphous silicon films and transparent zinc oxide films doped Al2O3(AZO) had been researched to improve these problems above. The following conclusions have been obtained.a) Polycrystalline silicon substrates were textured by new etching processing. The results showed that, as the NH4NO3concentration in the etching solution increased, the number of corrosion pits on the sample increased and then decreased, the surface light reflectivity decreased first and then increased. At the NH4NO3content of4ml, the surface presented the lowest reflectivity. With ultrasound assistance, corrosion rate of polycrystalline silicon surface slowed down significantly, corrosion pits more uniform and surface light reflectivity even lower.b) Intrinsic and doped amorphous thin silicon films were prepared using the ECR-PECVD. Results indicated that, with the elevation of Ar/H2ratio, crystalline volume fraction of a-Si:H thin film decreased, the deposition rate decreased, the optical band gap first increased and then decreased. With the increase of flow rate of SiH4, deposition rate of a-Si:H increased and crystalline volume fraction decreased. At the Ar/H2ratio of15/15and SiH4flow rate of10sccm, the deposited intrinsic amorphous silicon film shows the best properties. As the doping concentration increased. the optical band gap of the as-deposited N-type a-Si:H thin films increased, the dark conductivity first increased and then decreased. At the doping concentration of0.5, the optical band gap and dark conductivity reached maximum at2.02eV and8.24×10-2S/cm. respectively.c) A series of AZO thin films were prepared under different deposition conditions using the double-target sputtering method. The results demonstrated that, at the substrate temperature of250℃. sputtering power of100W and work pressure of0.3Pa. the as-deposited AZO thin films showed better compositive performance and crystalline quality with the resistivity of2.5×10-3Ω·cm, the visible light transmittance of about90%. and the optical band gap of3.52eV. Compared with single-target magnetron sputtering, AZO thin films prepared by the double-target sputtering method possessed better orientation, crystallinity, and optical and electrical properties.