Laser processing of crystalline silicon solar cells

Influence of laser power on the properties of laser doped solar cells

“…Saturation occurs when the process becomes source limited: under these conditions the number of dopant atoms and not the melting time limits the diffusion process. Increased SHR for increasing diode current (above some threshold current) was observed by others [31] and could be explained by evaporation of silicon with dopants during ablation or a decrease of doping homogeneity. Fig.…”

“…High efficiencies using different substrates and SODs have been obtained using this method [30][31][32]. It is worth noting that the laser doping process can be employed for a variety of applications, including formation of a large area emitter [31,33], selective emitter [8,30,[34][35] and Back Surface Field (BSF) [17,36].…”

Laser induced defects in laser doped solar cells

“…They speculated that the formation of stacking faults results from a single mistake in the stacking of atoms during the crystal growth 6. Defect‐free recrystallised zones were also achieved using different types of lasers 7, 8.…”

“…Rapid cooling was found to create such defects, which severely limit the carrier lifetime in the recrystallised area 9, 10. In solar cells these point defects lower the minority carrier lifetime and hence the open circuit voltage 11, 15, 16. The critical recrystallisation velocity was determined to be 1–1.5 m/s; velocities above this value produce high levels of defects 17, 18.…”

“…In recent years, increased attention has been directed to the use of laser doping in the fabrication of solar cells. Different approaches have been used by different research groups, such as the ‘line beam’ of the University of Stuttgart 7, 31 or the laser chemical processing (LCP) of the Fraunhofer Institute for Solar Energy 32, 33. At the University of New South Wales (UNSW), a new laser doping method has been developed for creating selective emitters 34.…”