Doping profile effect of shallow emitter junction in selective emitter c-Si solar cell with reactive ion etching etch back process

The fabrication of a selective emitter solar cell and its theoretical detail has been discussed in this paper. We evaluated the diffusion profiles of lightly doped regions by fixing the sheet resistance as 100 Ω/sq using PC1D. It shows that main factors for high efficiency and high current density solar cells are carrier recombination and mobility. These factors are mostly influenced by emitter junction depth (X_j). When the junction depth was varied from 0.02 μm to 3.45 μm, the current density reduced from 39 mA-cm^-2 to 28 mA-cm^-2 showing better current density with the shallow emitter layer. Fabrication of the etch-back selective emitter was done by reactive ion etching (RIE). Using the etch-back process, we obtained an improved short circuit current density (J_sc) (36.7 mA-cm ^-2), and an improved fill factor (78.4%) at constant open circuit voltage (V_oc) (628.2 mV), as compared to the reference of the homogeneous doping profile. The concentration gradient from the etch-back structure of the selective emitter provides a more effective collection of minority carriers.