▁has ▁been ▁conducted ▁by ▁independently ▁fund ed ▁labor ator ies . ▁However , ▁H eli ov olt ▁claimed ▁a ▁top ▁cell ▁efficiency ▁of ▁ 1 2 . 2 %. ▁ ▁Co ev ap oration ▁▁ ▁Co ev ap oration , ▁or ▁code position , ▁is ▁the ▁most ▁pre val ent ▁C IG S ▁fabric ation ▁technique . ▁Bo eing ' s ▁co ev ap oration ▁process ▁depos its ▁bil ay ers ▁of ▁C IG S ▁with ▁different ▁sto ichi omet ries ▁onto ▁a ▁he ated ▁substr ate ▁and ▁allows ▁them ▁to ▁inter mix . ▁ ▁N RE L ▁developed ▁another ▁process ▁that ▁involves ▁three ▁de position ▁steps ▁and ▁produced ▁the ▁current ▁C IG S ▁efficiency ▁record ▁holder ▁at ▁ 2 0 . 3 %. ▁The ▁first ▁step ▁in ▁N RE L ' s ▁method ▁is ▁code position ▁of ▁In , ▁Ga , ▁and ▁Se . ▁This ▁is ▁followed ▁by ▁Cu ▁and ▁Se ▁depos ited ▁at ▁a ▁higher ▁temperature ▁to ▁allow ▁for ▁diffusion ▁and ▁inter mix ing ▁of ▁the ▁elements . ▁In ▁the ▁final ▁stage ▁In , ▁Ga , ▁and ▁Se ▁are ▁again ▁depos ited ▁to ▁make ▁the ▁overall ▁composition ▁Cu ▁def ic ient . ▁ <0x09> ▁Wür th ▁Sol ar ▁began ▁producing ▁C IG S ▁cells ▁using ▁an ▁inline ▁co ev ap oration ▁system ▁in ▁ 2 0 0 5 ▁with ▁module ▁effic ien cies ▁between ▁ 1 1 % ▁and ▁ 1 2 %. ▁They ▁opened ▁another ▁production ▁facility ▁and ▁continued ▁to ▁improve ▁efficiency ▁and ▁yield . ▁Other ▁companies ▁scaling ▁up ▁co