Poly Silicon on Oxide Contact Silicon Solar Cells
Name:
Jingxuan Kang - Thesis - Final Draft.pdf
Size:
3.613Mb
Format:
PDF
Description:
Jingxuan Kang - Thesis - Final Draft
Type
ThesisAuthors
Kang, Jingxuan
Advisors
De Wolf, Stefaan
Committee members
Laquai, FrédéricOoi, Boon S.
Program
Material Science and EngineeringKAUST Department
Physical Science and Engineering (PSE) DivisionDate
2019-04-17Permanent link to this record
http://hdl.handle.net/10754/652926Metadata
Show full item recordAccess Restrictions
At the time of archiving, the student author of this thesis opted to temporarily restrict access to it. The full text of this thesis became available to the public after the expiration of the embargo on 2020-05-16.Abstract
Silicon photovoltaic (PV) is a promising solution for energy shortage and environmental pollution. We are experiencing an era when PV is exponentially increasing. Global cumulative installation had reached 380 GW in 2017. Among which, silicon-based PV productions share more than 90% market. Performance of the first two-generation commercial popular silicon solar cells - Al-BSF and PERC - are limited by metal/Si contacts, where interface defects significantly reduce the open-circuit voltage. In this context, full-area passivation concepts are proposed for c-Si solar cells, with expectation to enhance the efficiency via reducing carrier recombination loss at the contact regions. In this thesis, poly silicon on oxide (POLO) passivating contact is developed for high efficiency c-Si solar cells. We unveiled the working mechanisms of POLO cells and then optimized the device performance based on our conclusion. We use boiling nitric acid to oxidize c-Si surface, which is of significance to determine the POLO working mechanisms. Phosphorus and boron doped silicon films are deposited by plasma enhanced vapor deposition (PECVD) or low-pressure vapor deposition (LPCVD) followed by high temperature (>800°C) annealing. SiOx structural evolution process under different annealing temperature was observed and the corresponding effects on passivation have been elucidated. The carrier transport mechanisms in the POLO contact annealed at high temperature, e.g. 800°C 900°C, were explored. We unveil that carrier transport in POLO structure is a combination of tunneling and pinhole transport, but dominant at varied temperature regions. Phosphorus-doped n-type POLO contact is optimized by several parameters, such as doping concentration, film thickness, annealing temperature, film deposition temperature, film relaxation time during annealing process, etc. We successfully obtained minority carrier lifetime over 10ms and contact resistivity lower than 30 mΩ·cm2. Boron-doped p-type POLO contact is also optimized by changing the doping concentration and annealing temperature. Finally, further hydrogen passivation is applied to enhance p-type POLO contact passivation, achieving an iVoc>690 mV, J0 <5 fA/cm2 and contact resistivity 1.3 mΩ·cm2. With the optimized n-type and p-type POLO contacts, an efficiency over 18% is achieved on n-type c-Si solar cells with a flat front surface.Citation
Kang, J. (2019). Poly Silicon on Oxide Contact Silicon Solar Cells. KAUST Research Repository. https://doi.org/10.25781/KAUST-9J932Scopus Count
Related items
Showing items related by title, author, creator and subject.
-
Colloidal Photoluminescent Amorphous Porous Silicon, Methods Of Making Colloidal Photoluminescent Amorphous Porous Silicon, And Methods Of Using Colloidal Photoluminescent Amorphous Porous Silicon(2015-04-09) [Patent]Embodiments of the present disclosure provide for a colloidal photoluminescent amorphous porous silicon particle suspension, methods of making a colloidal photoluminescent amorphous porous silicon particle suspension, methods of using a colloidal photoluminescent amorphous porous silicon particle suspension, and the like.
-
Synthesis of Silicon and Silicon Carbide Nanoparticles by Pulsed Electrical Discharges in Dielectric Liquids(Plasma Chemistry and Plasma Processing, Springer Science and Business Media LLC, 2021-09-07) [Article]Silicon carbide (SiC) has been widely used in many applications, which require high mechanical endurance or high electrical resistance. It also serves as a basic material for light emitting diodes. Here, we present an in-liquid plasma method to produce SiC nanoparticles. A sustained spark-discharge in a dielectric liquid, which is energized by a nanosecond pulsed power supply, is established for the synthesis. To provide Si and C, we employed graphite and silicon as electrodes and cyclohexane (CHX) and tetramethylsilane (TMS) as dielectric liquids. For a reasonable comparison, we tested various combinations of electrode and liquid, namely Si-to-C in CHX, Si-to-Si in CHX, and C-to-C in TMS. We found that discharges in CHX produce Si particles encapsulated in C-shell and Si nanoparticles in C-matrix. Meanwhile, discharges in TMS consistently produce SiC nanoparticles with an average size of ~ 10 nm, regardless of the electrode material.
-
Nanocrystalline Silicon Carrier Collectors for Silicon Heterojunction Solar Cells and Impact on Low-Temperature Device Characteristics(IEEE Journal of Photovoltaics, Institute of Electrical and Electronics Engineers (IEEE), 2016-09-26) [Article]Silicon heterojunction solar cells typically use stacks of hydrogenated intrinsic/doped amorphous silicon layers as carrier selective contacts. However, the use of these layers may cause parasitic optical absorption losses and moderate fill factor (FF) values due to a high contact resistivity. In this study, we show that the replacement of doped amorphous silicon with nanocrystalline silicon is beneficial for device performance. Optically, we observe an improved short-circuit current density when these layers are applied to the front side of the device. Electrically, we observe a lower contact resistivity, as well as higher FF. Importantly, our cell parameter analysis, performed in a temperature range from -100 to +80 °C, reveals that the use of hole-collecting p-type nanocrystalline layer suppresses the carrier transport barrier, maintaining FF s in the range of 70% at -100 °C, whereas it drops to 40% for standard amorphous doped layers. The same analysis also reveals a saturation onset of the open-circuit voltage at -100 °C using doped nanocrystalline layers, compared with saturation onset at -60 °C for doped amorphous layers. These findings hint at a reduced importance of the parasitic Schottky barrier at the interface between the transparent electrodes and the selective contact in the case of nanocrystalline layer implementation. © 2011-2012 IEEE.
