Influence of doping profile of highly doped regions for selective emitter solar cells

Abstract

The influence of the doping profile under the metallization for laser doped selective emitter solar cells is investigated. Laser doping allows profile tailoring to some extent by adapting the pulse energy, resulting in Gaussian doping profiles. Numerical calculations using PC1D show that the doping profile influences the recombination at the metal-semiconductor interface. The value J0e,met is used to characterize this influence on solar cell level employing calculations with the 2-diode-model. Selective emitter solar cells have been fabricated to validate, whether this effect can be observed on cell level. IV measurements show a dependence of the open circuit voltage on the profile. This is determined to be partly due to a different 2nd diode recombination current J02 for different doping profiles underneath the contact. The effect of J0e,met is also ascertainable

2-D Numerical analysis of the impact of the highly-doped profile on selective emitter solar cell performance

“…2. For a given dose, a lower Cpeak and hence a deeper junction is slightly beneficial for the Voc because of the reduction of the total saturation current density due to the following combined effects: i) a lower doping leads to a lower surface recombination velocity in the passivated HDOP illuminated areas and to a reduced impact of the band-gap narrowing in the emitter (therefore lower values of effective intrinsic carrier density); ii) a deeper junction allows the reduction of the emitter saturation current density in the metallized regions, as already demonstrated in [2]. However, this analysis does not reveal a strong dependence of the Voc on the HDOP profile: the maximum variation of the Voc is limited to 3.2 mV (~0.5%).…”

“…In this work we have analyzed the influence of the HDOP profile on the performance of a c-Si SE solar cell. With respect to [2], where this influence was investigated by using a one-dimensional (1-D) analytical modeling, we have performed two-dimensional (2-D) numerical simulations by using a TCAD simulator [3] in order to evaluate the impact of different HDOP profiles on the cell parameters, such as the short-circuit current density (Jsc), the open-circuit voltage (Voc) ,the fill factor (FF) and the efficiency (η). Moreover, by taking into account the large alignment tolerances used in the processing step to create the selective emitter diffusion for the subsequent metallization process, we have estimated the achievable benefit in terms of efficiency by reducing the lateral width of the highly-doped areas in a SE solar cell.…”

Bifacial p-Type PERC Solar Cell with Efficiency over 22% Using Laser Doped Selective Emitter

“…The main methods of forming selective emitters include oxide masking, screen printing silicon ink, ion implantation and laser doping. In order to lower the thermal budget and make the process more compatible with the existing standardized production line, laser-doping (LD) was proposed as an alternative way to form the selective emitter [15][16][17][18][19][20]. For PERC cell production line, selective emitter (SE) based on PERC cell has more advantages than that based on regular p-type cells.…”

Boron laser doping using spin-on dopant for textured crystalline silicon solar cell

“…25) The SE can break the trade-off between Auger recombination and series resistance because of the formation of a heavily doped area underneath metal contacts and a lightly doped area on other areas of the surface. 26,27) However, the fabrication of SEs by the conventional thermal process requires extra heating and photolithography processes that include chemical steps. These processes have high additional costs and a decreased yield rate, especially when using a thin substrate.…”