▁is ▁independent ▁of ▁defect ▁concentration . ▁In ▁a ▁similar ▁experiment , ▁one ▁can ▁just ▁lower ▁the ▁temperature ▁of ▁the ▁conduct or ▁( Fig ure ▁ 3 ) ▁so ▁that ▁ph on on ▁density ▁decre ases ▁to ▁neg lig ible ▁allowing ▁defect ▁dominant ▁resist ivity . ▁With ▁this ▁case , ▁ σ ▁= ▁ne 2 τ ▁/ m * ▁can ▁be ▁used ▁to ▁directly ▁calculate ▁ τ ▁for ▁defect ▁scatter ing . ▁ ▁Pass iv ation ▁ ▁Sur face ▁defect s ▁can ▁always ▁be ▁" pass iv ated " ▁with ▁atoms ▁to ▁purpose fully ▁occup y ▁the ▁corresponding ▁energy ▁levels ▁so ▁that ▁condu ction ▁electrons ▁cannot ▁scatter ▁into ▁these ▁states ▁( effect ively ▁decre asing ▁n ▁in ▁Eq ▁( 1 0 )). ▁For ▁example , ▁Si ▁pass iv ation ▁at ▁the ▁channel / ox ide ▁interface ▁of ▁a ▁M OS F ET ▁with ▁hydro gen ▁( Fig ure ▁ 4 ) ▁is ▁a ▁typical ▁procedure ▁to ▁help ▁reduce ▁the ▁~ 1 0 1 0 ▁cm − 2 ▁defect ▁density ▁by ▁up ▁to ▁a ▁factor ▁of ▁ 1 2 ▁thereby ▁impro ving ▁mob ility ▁and , ▁hence , ▁switching ▁spe eds . ▁Rem oval ▁of ▁inter medi ary ▁states ▁which ▁would ▁otherwise ▁reduce ▁t unn eling ▁bar riers ▁also ▁decre ases ▁gate ▁leak age ▁current ▁and ▁increases ▁gate ▁capac it ance ▁as ▁well ▁as ▁trans ient ▁response . ▁The ▁effect ▁is ▁that ▁the ▁Si ▁sp 3 ▁bond ing ▁becomes ▁fully ▁satisfied . ▁The ▁obvious ▁requirement ▁here ▁is ▁the ▁ability ▁for ▁the ▁sem icon duct or