CEMMNT partner, Taylor Hobson, launches CCI SunStar, leading the world in the next generation of combined thin film dimensional optical profilers. This instrument merges world-leading non-contact dimensional measurement capabilities with advanced thin and thick film technology. The CCI SunStar is able to meet the most demanding application challenges, including 1st and 2nd generation Solar PV, High power LED, Displays and Vacuum Coatings.
The unique features of the CCI SunStar include:
- 4 million pixel camera for high resolution imaging over a large area
- Film thickness measurement from 5 u down to 300 nm or less
- Auto-range and auto-fringe-find for ease of use
- Single mode of operation over all scan ranges for data you can trust
- Strong, stable and robust closed loop Z scanning mechanism
One of the new and exciting application areas is the PV Solar Cells
Recent developments in the design and manufacturing of PV solar cells offer improvements in efficiency and reduction in costs. These advantages are increasing the use of solar cells to replace traditional energy sources.
Solar Cell Design
There are multiple approached to solar cell design and the different approached are often divided into 3 separate categories; first generation, second generation and third generation.
First Generation Solar Cells
These are produced using crystalline silicon. This is the traditional solar cell approach and the majority of current solar cells are produced using this technology. Controlling the depth of scribe lines and the texture of the surface are important parts of solar cell manufacture. The Talysurf CCI is ideal for looking at these parameters in a single measurement. The roughness and trench depth can both be studied at the same time because every measurement has sub nanometre resolution, regardless of the scan range. Typically, the whole measurement and analysis takes less than 1 minute to set up and measure (using auto-fringe-find and auto-range). The average trench depth is the equivalent of over 2,000 stylus measurements and over 4 million data points are collected in each measurement. The large number of data points allows the study of surface roughness at the same time as the trench depth. The benefit of this multi-analysis approach is that it speeds up the metrology involved in process control, making it more cost effective.
Second Generation Solar Cells
These are based on thin film semiconductor materials. This design of solar cell is now becoming more common and it is expected that production of second generation solar cells will increase significantly in the next few years. Measurement of thin films using optical techniques can present some potential problems. The main issue arises from different signals from different layers influencing the final measurement data and producing an incorrect answer. It is possible to measure the thickness of semi-transparent film coating when it is greater than 1 - 2 micrometres and less than 20 micrometres using Thick Film analysis. The high Z resolution of the Coherence Correlation Interferometry (CCI) technique makes it an ideal method for measuring these film thickness because of the sub nanometre resolution over this range. For films thinner than 1 - 2 micrometres a different approach has to be used. Taylor Hobson has released its film thickness software for measuring these thinner films on the CCI SunStar interferometer. The CCI SunStar is capable of measuring film thickness of semi-transparent films from 5 micrometres down to 300 nm or less. The range of thickness that can be measured will vary from material to material depending on the optical properties of the film. The film thickness software is suitable for measuring many types of film including Cadmium Telluride (CdTe), Copper Indium Gallium Diselenide (CIGS), Indium Tin Oxide (ITO), Zinc Oxide and Titanium Dioxide which are often found in the solar cells.
Third Generation Solar Cells
This term is often used to describe new approaches to photovoltaic solar cell design. The flexibility of the CCI SunStar makes it ideal for the study of the new materials and structures often used in these solar cells.