Laser optics module with uniform 200 mm laser line for solar cell annealing

The business unit Laser Systems with its company INNOVAVENT GmbH (Goettingen, Germany) presented the generation of a uniform laser line with green laser light. The INNOVAVENT Laser Optics is the key technology for uniform large area illumination which combines laser and optical system to the highest performance.

From Jenoptik (Jena, Germany; www.jenoptik.com) for the crystallization process of 50 nm thick silicon layers a new Volcano Laser Optics is available which creates a homogeneous 200 mm long laser line. This optical system is driven by the Dual Asama laser module which delivers up to 16 mJ at 10 kHz.

Crystallization of 50 nm silicon films is an important application for the manufacturing of thin film transistors for LCD and OLED displays. Particularly outstanding is the extremely uniform crystallization which is required for OLED displays and which can be achieved with the Volcano laser line.

The 200 mm long line allows the manufacture of mobile displays up to 15in size with high throughput and at low costs.

A 5–10 μm wide Volcano laser line for production of thin film silicon solar cells is presently under evaluation. The investigations focus on the creation of crystalline seed layers of 50 nm thickness for the design of highly efficient 2 μm thin film cells.

A specially adapted Volcano optical system allows laser doping of crystalline solar cells. Green laser technology is particularly suited for localized doping of the semiconductor layer below the contact fingers in order to increase cell efficiency.

With the newly achievable pulse duration of 1,200 ns laser backside annealing of power transistors like IGBTs (Insulated Gate Bipolar Transistor) can be obtained up to a depth of 2 μm. This widens the application range of laser backside annealing to IGBTs into the kV range.