▁Si O 2 ▁is ▁not ▁only ▁a ▁good ▁ins ulator ▁( with ▁a ▁band ▁gap ▁of ▁ 8 . 9 ▁e V ), ▁but ▁the ▁Si - Si O 2 ▁interface ▁can ▁be ▁easily ▁engine ered ▁to ▁have ▁excellent ▁elect rical ▁properties , ▁most ▁important ly ▁low ▁density ▁of ▁interface ▁states . ▁Ga As ▁does ▁not ▁have ▁a ▁native ▁ox ide , ▁does ▁not ▁easily ▁support ▁a ▁stable ▁ad her ent ▁ins ulating ▁layer , ▁and ▁does ▁not ▁possess ▁the ▁die lect ric ▁strength ▁or ▁surface ▁pass iv ating ▁qual ities ▁of ▁the ▁Si - Si O 2 . ▁ ▁Al umin um ▁ox ide ▁( Al 2 O 3 ) ▁has ▁been ▁extens ively ▁studied ▁as ▁a ▁possible ▁gate ▁ox ide ▁for ▁Ga As ▁( as ▁well ▁as ▁In G a As ). ▁ ▁The ▁third ▁advantage ▁of ▁sil icon ▁is ▁that ▁it ▁poss esses ▁a ▁higher ▁hole ▁mob ility ▁compared ▁to ▁Ga As ▁( 5 0 0 ▁versus ▁ 4 0 0   cm 2 V − 1 s − 1 ). ▁This ▁high ▁mob ility ▁allows ▁the ▁fabric ation ▁of ▁higher - speed ▁P - channel ▁field ▁effect ▁trans ist ors , ▁which ▁are ▁required ▁for ▁C M OS ▁logic . ▁Because ▁they ▁lack ▁a ▁fast ▁C M OS ▁structure , ▁Ga As ▁circ uits ▁must ▁use ▁logic ▁styles ▁which ▁have ▁much ▁higher ▁power ▁consumption ; ▁this ▁has ▁made ▁Ga As ▁logic ▁circ uits ▁unable ▁to ▁comp ete ▁with ▁sil icon ▁logic ▁circ uits . ▁ ▁For ▁manufact uring ▁solar