Four-Junction Wafer-Bonded Concentrator Solar Cells Dimroth, Frank; Tibbits, Thomas N. D.; Niemeyer, Markus ...
IEEE journal of photovoltaics,
2016-Jan., 2016-1-00, 20160101, Volume:
6, Issue:
1
Journal Article
Peer reviewed
Open access
The highest solar cell conversion efficiencies are achieved with four-junction devices under concentrated sunlight illumination. Different cell architectures are under development, all targeting an ...ideal bandgap combination close to 1.9, 1.4, 1.0, and 0.7 eV. Wafer bonding is used in this work to combine materials with a significant lattice mismatch. Three cell architectures are presented using the same two top junctions of GaInP/GaAs but different infrared absorbers based on Germanium, GaSb, or GaInAs on InP. The modeled efficiency potential at 500 suns is in the range of 49-54% for all three devices, but the highest efficiency is expected for the InP-based cell. An efficiency of 46% at 508 suns was already measured by AIST in Japan for a GaInP/GaAs//GaInAsP/GaInAs solar cell and represents the highest independently confirmed efficiency today. Solar cells on Ge and GaSb are in the development phase at Fraunhofer ISE, and the first demonstration of functional devices is presented in this paper.
The aim of the study was to develop a very simple process for the fabrication of large area n-type PERT cells by means of ion implantation. We showed an improvement of the implanted boron activation ...rate with the annealing temperature by comparing boron SIMS and ECV concentration profiles. A direct positive impact on the boron emitter saturation current density (J0e) was measured. We also investigated the effect of varying the oxidation conditions during the annealing on the implanted boron emitter and the phosphorus BSF quality. Low emitter saturation current density (J0e) of 131 fA/cm2 was measured on textured surfaces, close to the value obtained with diffused B-emitters.
A process flow was developed leading to an average efficiency of 19% on 239 cm2 bifacial solar cells, using only eight processing steps with two implantations and one activation annealing.
Si exfoliation by MeV proton implantation Braley, Carole; Mazen, Frédéric; Tauzin, Aurélie ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
04/2012, Volume:
277
Journal Article
Peer reviewed
Proton implantation in silicon and subsequent annealing are widely used in the Smart Cut™ technology to transfer thin layers from a substrate to another. The low implantation energy range involved in ...this process is usually from a few ten to a few hundred of keV, which enables the separation of up to 2μm thick layers. New applications in the fields of 3D integration and photovoltaic wafer manufacturing raise the demand for extending this technology to higher energy in order to separate thicker layer from a substrate. In this work, we propose to investigate the effect of proton implantation in single crystalline silicon in the 1–3MeV range which corresponds to a 15–100μm range for the hydrogen maximum concentration depth. We show that despites a considerably lower hydrogen concentration at Rp, the layer separation is obtained with fluence close to the minimum fluence required for low energy implantation. It appears that the fracture propagation in Si and the resulting surface morphology is affected by the substrate orientation. Defects evolution is investigated with Fourier Transform Infrared Spectroscopy. The two orientations reveal similar type of defects but their evolution under annealing appears to be different.
We developed a high efficiency N-type PERT (Passivated Rear Totally Diffused) bifacial structure based on B and P ion implantation doping, SiO2 passivation and conventional screen-printing ...metallization. Two process flows were compared: a “co-anneal” process and a process using separated anneals for B and P activation. We highlight the impact of the variations of the B- emitter and P- BSF profiles on the solar cells performance. The impact of the boron implantation dose was studied allowing to optimize this parameter. Concerning the BSF, two temperature ranges were studied for the P activation leading to very different BSF profiles. A shallower profile enables to reach high implied Voc while keeping low contact resistivity. The overall optimization was integrated into a simplified and industrial process flow on large area Cz-Si solar cells (239cm2). An average efficiency of 19.7% was reached using the “co-annealing” process. The efficiency in this case was limited by a low PFF. This limitation was solved using the “separated anneal” process where an average efficiency of 20.2% was obtained on a 15 cells batch with a 20.5% champion cell.
PDF
