Ultra-flat p-n junctions formed by solid source laser doping

Large area p-type PERL cells featuring local p+ BSF formed by laser processing of ALD Al2O3 layers

“…The latter is used to form, by means of pico-second (ps) laser processing, localized p þ Back-Surface-Field (BSF) regions at rear local contacts. Several approaches have been used in the past for laser doping [12][13][14]; however, in this work we focus on the use of a self-aligned process as it is used for the laser doped selective emitter technology [15]. In this way the dielectric ablation and the local-BSF are formed simultaneously by laser processing and the firing step to form the local-BSF via Al-Si alloying is not needed anymore.…”