Large Grained, Low Defect Density Polycrystalline Silicon on Glass Substrates by Large- area Diode Laser Crystallisation

摘要

A new method to form high quality crystalline silicon thin films on cheap glass substrates is developed using a single pass of a line-focus cw diode laser in air. The laser process results in the formation of large high-quality crystals as they grow laterally in the scan direction - seeded by the previously crystallised region. Grains 10 urn in thickness, up to millimetres in length and hundreds of microns in width have been grown with virtually zero detectable intra-grain defects. Another mode is found which results in much smaller crystals grown by partial melting. The dominant grain boundaries identified are Σ3 <111> 60° twins. Hall mobilities as high as 470 cm~2/Vs have been recorded. A diffused emitter is used to create a p-n junction at the rear of the films which produces open-circuit voltages as high as 539 mV.