▁shall ow ▁defect ▁states ▁close ▁to ▁band ▁edges . ▁Fort un ately , ▁F erm i ' s ▁golden ▁rule ▁itself ▁is ▁quite ▁general ▁and ▁can ▁be ▁used ▁for ▁deep ▁state ▁defect s ▁if ▁the ▁interaction ▁between ▁condu ction ▁electron ▁and ▁defect ▁is ▁understood ▁well ▁enough ▁to ▁model ▁their ▁interaction ▁into ▁an ▁operator ▁that ▁rep laces ▁H '. ▁ ▁Ex perimental ▁measurements ▁ ▁Det erm ination ▁of ▁the ▁extent ▁these ▁d ang ling ▁b onds ▁have ▁on ▁elect rical ▁transport ▁can ▁be ▁experiment ally ▁observed ▁fairly ▁readily . ▁By ▁swe eping ▁the ▁voltage ▁across ▁a ▁conduct or ▁( Fig ure ▁ 3 ), ▁the ▁resistance , ▁and ▁with ▁a ▁defined ▁geometry , ▁the ▁conduct ivity ▁of ▁the ▁sample ▁can ▁be ▁determined . ▁As ▁mentioned ▁before , ▁ σ ▁= ▁ne 2 τ ▁/ m *, ▁where ▁ τ ▁can ▁be ▁determined ▁knowing ▁n ▁and ▁m * ▁from ▁the ▁F erm i ▁level ▁position ▁and ▁material ▁band ▁structure . ▁Unfortunately , ▁this ▁value ▁contains ▁effects ▁from ▁other ▁scatter ing ▁mechan isms ▁such ▁as ▁due ▁to ▁ph on ons . ▁This ▁g ains ▁useful ness ▁when ▁the ▁measurement ▁is ▁used ▁alongside ▁Eq ▁( 1 1 ) ▁where ▁the ▁slope ▁of ▁a ▁plot ▁of ▁ 1 / τ ▁versus ▁n ▁makes ▁E c - E db ▁calcul able ▁and ▁the ▁intercept ▁determ ines ▁ 1 / τ ▁from ▁all ▁but ▁defect ▁scatter ing ▁processes . ▁This ▁requires ▁the ▁assumption ▁that ▁ph on on ▁scatter ing ▁( am ong ▁other , ▁possibly ▁neg lig ible ▁processes )