▁per ▁square " ▁is ▁that ▁a ▁square ▁sheet ▁with ▁sheet ▁resistance ▁ 1 0   oh m / square ▁has ▁an ▁actual ▁resistance ▁of ▁ 1 0   oh m , ▁regardless ▁of ▁the ▁size ▁of ▁the ▁square . ▁( For ▁a ▁square , ▁, ▁so ▁. ) ▁The ▁unit ▁can ▁be ▁thought ▁of ▁as , ▁lo os ely , ▁" oh ms ▁· ▁aspect ▁ratio ". ▁ ▁Example : ▁ ▁A ▁ 3 - unit ▁long ▁by ▁ 1 - unit ▁wide ▁( as pect ▁ratio ▁= ▁ 3 ) ▁sheet ▁made ▁of ▁material ▁having ▁a ▁sheet ▁resistance ▁of ▁ 2 1   Ω / sq ▁would ▁measure ▁ 6 3   Ω ▁( since ▁it ▁is ▁composed ▁of ▁three ▁ 1 - unit ▁by ▁ 1 - unit ▁squares ), ▁if ▁the ▁ 1 - unit ▁edges ▁were ▁attached ▁to ▁an ▁oh mm eter ▁that ▁made ▁contact ▁entirely ▁over ▁each ▁edge . ▁ ▁For ▁sem icon duct ors ▁ ▁For ▁sem icon duct ors ▁do ped ▁through ▁diffusion ▁or ▁surface ▁pe aked ▁ion ▁impl ant ation ▁we ▁define ▁the ▁sheet ▁resistance ▁using ▁the ▁average ▁resist ivity ▁ ▁of ▁the ▁material : ▁ ▁which ▁in ▁materials ▁with ▁majority - car rier ▁properties ▁can ▁be ▁approxim ated ▁by ▁( neg lect ing ▁intr insic ▁charge ▁carri ers ): ▁ ▁where ▁ ▁is ▁the ▁j unction ▁depth , ▁ ▁is ▁the ▁majority - car rier ▁mob ility , ▁ ▁is ▁the ▁car rier ▁charge , ▁and ▁ ▁is ▁the ▁net ▁imp urity ▁concentration ▁in