Conversion efficiency and process stability improvement of electron beam crystallized thin film silicon solar cells on glass

• Electron beam crystallization was successfully transferred to non-SiCx interlayers with focus on SiO2.
• Significant improvements in terms of process window and uniformity of the crystallization process were achieved using adequate capping layers.
• Silicon absorbers crystallized on SiO2 interlayers exhibit almost 10x higher band-to-band PL signal compared to silicon films crystallized on SiCx.
• Combined with hydrogen passivation a new efficiency record of 7.8% (9% emitter area) was achieved using an adapted single-sided contact system.

Liquid phase crystallization (LPC) using e-beam or CW-laser line sources of amorphous or nanocrystalline silicon films has emerged as new method to form high quality absorbers on cheap substrates. A disadvantage of electron beam crystallization was the necessity to use amorphous SiCxSiCx layers in contact with the silicon to maintain a stable crystallization process, resulting in high surface recombination. In this work we investigate capping layers to enable e-beam induced LPC on alternative interlayer materials especially SiO2SiO2 and characterize the morphological and electrical properties of these layer stacks. Photoluminescence measurements of LPC absorbers on SiO2SiO2 layers exhibit significantly increased radiative recombination compared to SiCxSiCx. Fabricated hetero-junction cells achieved a new emitter area efficiency record for electron beam induced LPC solar cells of 9% using the FrontERA contact system and H passivation.