Laser Sculpting and Processing of Silicon for Photovoltaics

Direct writing of photonic and fluidic devices in Si by means of laser processing is of great importance as it promisses low-cost, rapid fabrication of Si devices. Although Si microfabrication techniques are well-established and technologically mature, the fabrication time and costs are still of importance as clean room environment, repetitive photomasking, mask aligning, thermal processing steps are typical requirements. Advancements in fiber laser technology has reached a stage such that high average power, nano to femtosecond pulsed lasers are reduced in dimension to about a square meter breadboard area and system costs are reduced to a fraction of a mask aligner. When integrated with galvo-, mechano-, acousto- or piezo-scanners, arbitrary 2D and 3D scan patterns of laser focus can easily be achieved. When the beam qualities are carefully selected, compatible materials can be opto-thermally proccesed in 2D and 3D. In this talk I will present sculpting of crystalline Si by 1550 nm wavelength, ns/fs pulsed fiber lasers. I will show some of our results demonstrating direct writing of holographic phase plates, microelectromechanical systems and buried channels which are fabricated by our novel laser assisted Si sculpting technique. Furthermore I will show slicing of crystal Si thin films out of bulk with the potiential for thin crystal Si solar cell fabrication, and also demonstrate direct written photonic interfaces for improved light management in silicon solar cells