NXT GmbH specializes in optical measurement systems for inline and offline process control in solar cell production
The Helios product family covers critical characterization needs across PERC, TOPCon, HJT, IBC, and tandem cells, measuring parameters such as layer thickness
Helios-rc, Helios-tn, and Helios-r8 enable application-specific monitoring, including textured surfaces, functional dielectric stacks, and poly-Si layers in TOPCon structures
NXT GmbH, a Germany-based characterization tool builder, specializes in high-precision spectrometric measurement systems for industrial and laboratory applications. The company has a 34-year history in optical metrology and offers both inline and offline measurement systems. These tools enable non-destructive analysis of thin-film properties such as layer thickness, refractive index, and reflectance/transmittance or both.
Specific to solar cell manufacturing, the company provides characterization solutions for critical process steps of production lines for all cell architectures – PERC, TOPCon, HJT, IBC, and tandem. Its Helios product family offers a wide range of systems for various stages of the cell production process. They are available in both inline and offline versions, where the offline systems have either manually operated for lab applications or can also be motorized for x-y mapping – a scan configuration. These tools are compatible with a range of materials, including dielectrics, semiconductors, and transparent conductive oxides (TCOs), on substrates such as glass, silicon wafers, and films (see NXT Measuring Technology’s PV Cell Inline Process Quality Control Tool).
The company has 3 major inline process control measurement tools – NXT Helios-rc, NXT Helios-tn, and NXT Helios-r8. The company promotes its NXT Helios-rc tool for measuring the total reflectance of the textured front side and the spatial angle reflectance of the rear side of the wafer. It supports a spectral acquisition speed of less than 100 ms. It can also measure the color and thickness of thin film layers, such as anti-reflective coatings.
NXT Helios-tn is promoted for the characterization of functional layers such as SiNx, AlOx, SiOx, SiOxNy, TCO, ITO, and AZO used in various cell architectures. It is configured to measure layer thickness, optical constants (n&k), and the ellipsometric parameter (Psi) across single and multiple layers – SiNx, AlOx, SiOx, SiOxNy, TCO, ITO, AZO, et cetera. It also features the ability to measure 2-3 parameters simultaneously.
NXT has also developed a particular tool for TOPCon, called NXT Helios-r8. This tool is designed to measure the thickness and optical constants (n&k) of the poly-Si layers deposited on top of a thin tunneling oxide layer in a TOPCon cell structure. Its 8-channel multi-optics design enables it to remain stable and accurate even with fluctuations in wafer rotation, distance, or tilt. The company emphasizes that this is an important advantage over ellipsometers, adding that over 700 of these systems have already been installed worldwide.
The text is an edited excerpt from TaiyangNews’ latest Market Survey on Solar Cell Production Equipment 2025, which can be downloaded for free here.
