Plasma‐immersion ion implantation: A path to lower the annealing temperature of implanted boron emitters and simplify PERT solar cell processing

Abstract

Ion implantation is a suitable and promising solution for the massive industrialization of boron doping, which is a crucial process step for most next‐generation solar cells based on crystalline silicon (c‐Si). However, the use of ion implantation for boron doping is limited by the high temperature (in the 1050°C range) of the subsequent activation anneal, which is essential to dissolve the boron clusters and reach a high‐emitter quality. In this work, we propose the use of plasma‐immersion ion implantation (PIII) from B2H6 gas precursor instead of the standard beamline ion implantation (BLII) technique to decrease this temperature down to 950°C. PIII and BLII boron emitters were compared with annealing temperatures ranging from 950°C to 1050°C. Contrary to BLII, no degradation of the emitter quality was observed with PIII implants annealed at 950°C along with a full activation of the dopants in the emitter. At 1000°C, emitter saturation current densities (J0e) below 21 fA/cm2 were obtained using the PIII technique regardless of the tested implantation doses for sheet resistances between 110 and 160 Ω/sq. After metallization steps, the metal/emitter contact resistances were assessed, indicating that these emitters were compatible with a conventional metallization by screen‐printing/firing. The PIII boron emitters' performances were further tested with their integration in n‐type passivated emitter rear totally diffused (PERT) solar cells fully doped by PIII. Promising results already show a conversion efficiency of 20.8% using a lower annealing temperature than with BLII and a reduced production cost.

A comparative study on alternative industrial manufacturing routes for bifacial n‐PERT silicon solar cells

“…2 Considering the manufacturing steps, the current PERC solar cell production lines are seen to be adaptable to the PERT solar cells due to the many similarities in the fabrication techniques, such as surface texturing, diffusion process, removal of the heavily doped rear surface, deposition of dielectric layers (ALD: Al 2 O 3 and PECVD: SiN x ), and metal screen printing. 5 PERT solar cells have already been extensively studied in the literature with various fabrication routes, particularly based on the doping method, such as diffusion furnace, 6,7 ion implantation, [8][9][10][11] atmospheric pressure chemical vapor deposition (APCVD), 12 plasma-enhanced chemical vapor deposition (PECVD), 13 spin-on doping, 14,15 or their use together. One of the challenges for the fabrication of PERT solar cells is the existence of the two doping steps for the rear and front surfaces, which necessitate protecting one side while doping the other at least once in the use of double-side doping methods such as furnace diffusion.…”

Ion-irradiation of catalyst and electrode materials for water electrolysis/photoelectrolysis cells, rechargeable batteries, and supercapacitors

“…10,11 Ion irradiation can introduce nanocrystallization, ordered surface nanostructures, and latent tracks in the target materials. To date, ion-irradiation has been widely applied in a variety of fields such as solar cells, 12 biomedicine, 13 microelectronics 14–16 and renewable energy. 17…”

“…10,11 Ion irradiation can introduce nanocrystallization, ordered surface nanostructures, and latent tracks in the target materials. To date, ion-irradiation has been widely applied in a variety of fields such as solar cells, 12 bioand element doping, morphology control and material synthesis. Particularly, we have emphasized ion-irradiation advantages for boosting the performances of the device.…”

The effects of the fluence of electron irradiation on the structure and hydrogen evolution reaction performance of molybdenum disulfide

“…Ion beam modification techniques serve as an effective tool to provide controlled modification of two-dimensional materials for defect engineering and material functionalization. [24][25][26][27][28] Under controlled radiation conditions, different types of particles can be used to tune the properties of materials and produce desirable defects, while the introduction of irradiation-induced defects can significantly modulate the structural, chemical and physical properties of materials. [29][30][31][32][33][34] Different defect types and concentrations can be accurately obtained by controlling more precise irradiation parameters to achieve optimal modification of catalytic performance.…”