Disclosed is a method for processing a silicon wafer to a bifacial solar cell having a boron-doped silicon layer and an antireflection layer of silicon nitride on the back. To form the back serving as a doping source boron-containing layer is deposited directly on the silicon wafer. In this, an SiO A heat treatment ensures that boron diffuses from the boron-containing layer in the silicon wafer. is further described a manufacturable according to this method bifacial solar cell.

Titanium oxide (TiO2) was a commonly used anti-reflection coating (ARC) in the past, but has been displaced by silicon nitride (SiNx) due to its ability to both passivate n+ emitters and provide the appropriate optical properties required for effective ARCs (refractive index, transparency, stability over time). However, with growing interest in n-type wafers, which feature p+ emitters, and the inability of SiNx to provide effective field-effect passivation for p-type materials, other passivation materials are being actively investigated by the photovoltaics (PV) R&D community. Aluminum oxide (AlOx) is one of such materials due to its ability to provide both low interface defect densities and sufficient negative fixed charge. Although AlOx is transparent and stable, the refractive index isn't ideally matched for a Si/air or Si/encapsulant interface. To circumvent the poor index matching, it has been shown that a multi-layer passivation/ARC stack is possible, allowing for both good passivation and ideal refractive index and sparking a renewed interest in TiO2. The high quality passivation is obtained by using a thin passivation layer (<; 20 nm) like AlOx, followed by a low cost optical material such as TiO2 with a proper refractive index for an ARC. This paper addresses the optical and microstructural properties of TiO2 films deposited at various temperatures using an in-line atmospheric chemical vapor deposition system (APCVD). The TiO2 films are investigated by spectroscopic ellipsometry, reflectance spectroscopy and cross-sectional TEM. Additionally, experimental results for the ARC performance of multi-layer ARC structures featuring AlOx/TiO2 are presented.

One promising path to a reduced cost of crystalline silicon (c-Si) photovoltaics (PV) is to increase silicon usage efficiency by using thinner wafers. Many challenges arise when transitioning to thin wafer cells, including increased surface recombination at the rear side of the cell, increased wafer bowing, and a reduction in optical absorption due to a decreased optical path length within the silicon. Rear side passivation provides great promise in addressing these challenges. This paper addresses rear side dielectric configurations that can optimize back surface reflectance, in addition to providing excellent surface passivation. Optical modeling of various stack configurations is examined to explore the back surface reflectance at the Si-dielectric interface for different film combinations and thicknesses as a function of wavelength and internal angle of incidence. Specifically, configurations using aluminum oxide (AlOx), silicon nitride (SiNx), titanium dioxide (TiO2), and silicon dioxide (SiO2) were investigated with a focus on designing stack configurations that will also allow for high quality passivation and are compatible with a high-volume manufacturing environment.

A process for producing a differently on both sides of the doped semiconductor wafer. The invention relates to a process for producing a differently on both sides of the doped semiconductor wafer. According to the invention a first dielectric layer containing a first dopant at a first side of the semiconductor wafer and a second dielectric layer containing a second different from the first dopant, at a position different from the first second side of the semiconductor wafer by means of a respective APCVD process formed, which is diffused by means of a common heat treatment process, the first dopant into the first side of the semiconductor wafer and the second dopant into the second side of the semiconductor wafer. Using, for example for the production of silicon solar cells with dielectrically passivated back.

This paper focuses on the fast spatially resolved detection of material and / or processing induced shunting using fast illuminated Lock-In Thermography (iLIT). With this technique shunting can be detected spatially resolved within a measurement time of only 1 s and thus the method in principle can be used for inline characterisation. Points addressed are the influence of Lock-In frequency on spatial resolution and the effect of a lowered illumination intensity for a better selectivity between shunting and recombination induced generation of heat. The method is tested for different common sources of shunting in standard industrial-type solar cells (points like shunts, cracks, poor edge isolation, contaminations) and all major types of shunts under investigation can be detected in times relevant for inline characterisation.