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The use of plasma immersion ion implantation (PIII) is a relevant approach for the development of advanced solar cells technologies at lower cost (€/W p ). In this paper, we report on the development of homogeneous boron (B) doping of n-type crystalline silicon (cSi) substrate by the PIII technique. Using diborane (B 2 H 6 ) as gas precursor, various doping profiles were identified fitting the requirements for boron-doped emitters in n-type PERT solar cells. Particularly, saturation current density (J 0e ) of 50 fA/cm 2 were achieved on symmetrical samples for a 94 Ω/sg textured B-emitter passivated with SiO 2 /SiN stack. Bifacial n-type Passivated Emitter Rear Totally-diffused (n-PERT) solar cells were fabricated using the PIII technology and conversion efficiencies up to 19.8% on 239 cm 2 Cz-Si wafers were obtained. As a consequence, these results indicate that PIII can compete with beamline technology but will have lower running cost. It is therefore a promising technology to create high efficiency cSi solar cells. [ABSTRACT FROM AUTHOR]

A simple process for the fabrication of selective emitter structures on n-PERT cells is investigated, using shallow Boron emitters obtained by ion implantation. By tuning the emitter doping process parameters, J 0e values as low as 10 fA.cm -2 have been obtained with highly resistive profiles. Laser overdoping processes from AlO x passivating layers are tested on these profiles to locally increase the emitter conductivity and allow better contact properties. Through this process the emitter sheet resistance and doping profile may be locally controlled with a limited impact on the J 0e values. [ABSTRACT FROM AUTHOR]

In this work, we report on the fabrication and characterization of n-type c-Si solar cells whose p + emitters are based on laser processed aluminum oxide/silicon carbide (Al 2 O 3 /SiC x ) films. The p + emitter is defined at the rear side of the cell and it consists of point-like laser-diffused p + regions with a surface charge induced emitter in between based on the high negative charge located at the Al 2 O 3 /c-Si interface. These emitters are fabricated at low temperature (< 400 °C) and could be directly compared to silicon heterojunction emitters with the advantage that the deposition of a Transparent Conductive Oxide (TCO) film can be avoided, since they are based on p + /n c-Si homojunctions. Additionally, the involved films are transparent to the IR photons ( >1000 nm) that reach the rear surface of the cell resulting in an excellent back reflector. We fabricated solar cells with distance between p + regions or pitch ranging from 200 to 350 μm with a front surface based on silicon heterojunction technology. Best efficiency (18.1%) is obtained for a pitch of 250 μm as a consequence of the trade-off between V oc and FF values. [ABSTRACT FROM AUTHOR]

In this work, we report on the fabrication and characterization of n-type c-Si solar cells whose p+ emitters are based on laser processed aluminum oxide/silicon carbide (Al2O3/SiCx) films. The p+ emitter is defined at the rear side of the cell and it consists of point-like laser-diffused p+ regions with a surface charge induced emitter in between based on the high negative charge located at the Al2O3/c-Si interface. These emitters are fabricated at low temperature (< 400 °C) and could be directly compared to silicon heterojunction emitters with the advantage that the deposition of a Transparent Conductive Oxide (TCO) film can be avoided, since they are based on p+/n c-Si homojunctions. Additionally, the involved films are transparent to the IR photons (◻ >1000 nm) that reach the rear surface of the cell resulting in an excellent back reflector. We fabricated solar cells with distance between p+ regions or pitch ranging from 200 to 350 μm with a front surface based on silicon heterojunction technology. Best efficiency (18.1 %) is obtained for a pitch of 250 μm as a consequence of the trade-off between Voc and FF values. [ABSTRACT FROM AUTHOR]

A simple process for the fabrication of selective emitter structures on n-PERT cells is investigated, using shallow Boron emitters obtained by ion implantation. By tuning the emitter doping process parameters, J0e values as low as 10 fA.cm-2 have been obtained with highly resistive profiles. Laser overdoping processes from AlOx passivating layers are tested on these profiles to locally increase the emitter conductivity and allow better contact properties. Through this process the emitter sheet resistance and doping profile may be locally controlled with a limited impact on the J0e values. [ABSTRACT FROM AUTHOR]

Abstract: This study reports on a new contact scheme for Silicon Heterojunction (Si-HJ) solar cells having Interdigitated Back Contacts (IBC). This new geometry with two metallization levels is used to avoid any electrical shading above the emitter and Back Surface Field (BSF) busbars. IBC Si-HJ solar cells with bi-level metallization are here compared experimentally to standard devices having a single-level contact scheme. Relative increases of 2% in Fill Factor (FF) and 8% in short circuit current density (Jsc) have been obtained with this optimized contact geometry on medium area solar cells (5x5cm2). Moreover, this technology can be used to increase the number of busbars on large area solar cells and therefore reduce series resistance effects. [Copyright &y& Elsevier]

Abstract: This study deals with the introduction of Point Contact technology to enhance the efficiency of Interdigitated Back Contact (IBC) Silicon Heterojunction (Si-HJ) solar cells. For the study of point contacted Emitter and Back Surface Field (BSF), respectively Rear emitter (RE) Si-HJ cells and conventional Si-HJ cells are fabricated with different contact area fractions and different Emitter and BSF layers. It is shown that point contact area fraction should be above 16% to avoid performance losses for the different emitter stack. Emitter stack p-doped amorphous silicon on top of intrinsic amorphous silicon seems to be the most promising layer since it allows very high surface passivation level. Concerning point contacted BSF, further improvement of passivating stack and contact layer is still needed to allow an enhancement of cell efficiency. With an optimized geometry and further improvement of the passivating and contact layers, such structures may be suitable for an application on IBC Si-HJ devices. [Copyright &y& Elsevier]

Abstract: This study deals with the development and optimization of Interdigitated Back Contact (IBC) Silicon Heterojunction (Si-HJ) solar cells based on n-type crystalline silicon (c-Si) substrates. Both one-dimensional (1D) and 2D aspects of IBC Si-HJ cells are explored in this work. Rear Emitter (RE) Si-HJ cells are fabricated to study the influence of the emitter stack on 1D resistive losses. It is shown that the rear emitter stack has to be carefully designed to maintain a high surface passivation level without inducing series resistance (RSeries). On IBC Si-HJ structures, the influence of 2D features such as emitter contact fraction are confirmed both experimentally and by modeling. Using the screen printing technology, 25cm2 IBC Si-HJ structures have been fabricated with an efficiency of 15.7%. [Copyright &y& Elsevier]

Abstract: Previous simulations of interdigitated back contact silicon heterojunction (IBC-SiHJ) solar cells have indicated that front surface passivation is a critical factor in the performance of such cells. This is why we here focus on the effect of a front surface field (FSF) layer by 2D numerical modelling. A FSF layer made of a highly doped thin crystalline silicon top layer makes the cell performance insensitive to the surface recombination velocity up to quite high values (5000 cm/s). It also reduces the lateral resistance losses due to the increased lateral current through the doped layer particularly in IBC-SiHJ solar cells with large pitches. A FSF layer can also be produced by doped hydrogenated amorphous silicon due to the induced accumulation layer at the crystalline silicon surface. The positive effect of such layer strongly depends on the a-Si:H/c-Si interface quality. [ABSTRACT FROM AUTHOR]