▁band ▁gap ▁and ▁so ▁is ▁relatively ▁poor ▁at ▁em itting ▁light . ▁ ▁As ▁a ▁wide ▁direct ▁band ▁gap ▁material ▁with ▁resulting ▁resistance ▁to ▁radiation ▁damage , ▁Ga As ▁is ▁an ▁excellent ▁material ▁for ▁outer ▁space ▁electron ics ▁and ▁optical ▁windows ▁in ▁high ▁power ▁applications . ▁ ▁Because ▁of ▁its ▁wide ▁band ▁gap , ▁pure ▁Ga As ▁is ▁highly ▁resist ive . ▁Com b ined ▁with ▁a ▁high ▁die lect ric ▁constant , ▁this ▁property ▁makes ▁ ▁Ga As ▁a ▁very ▁good ▁substr ate ▁for ▁Integr ated ▁circ uits ▁and ▁unlike ▁Si ▁provides ▁natural ▁isol ation ▁between ▁devices ▁and ▁circ uits . ▁ ▁This ▁has ▁made ▁it ▁an ▁ideal ▁material ▁for ▁mon ol ith ic ▁mic row ave ▁integrated ▁circ uits ▁( MM IC s ), ▁where ▁active ▁and ▁essential ▁pass ive ▁components ▁can ▁readily ▁be ▁produced ▁on ▁a ▁single ▁slice ▁of ▁Ga As . ▁ ▁One ▁of ▁the ▁first ▁Ga As ▁micro process ors ▁was ▁developed ▁in ▁the ▁early ▁ 1 9 8 0 s ▁by ▁the ▁R CA ▁corpor ation ▁and ▁was ▁considered ▁for ▁the ▁Star ▁Wars ▁program ▁of ▁the ▁United ▁States ▁Department ▁of ▁Def ense . ▁These ▁process ors ▁were ▁several ▁times ▁faster ▁and ▁several ▁orders ▁of ▁magnitude ▁more ▁radiation ▁resist ant ▁than ▁their ▁sil icon ▁counter parts , ▁but ▁were ▁more ▁expensive . ▁Other ▁Ga As ▁process ors ▁were ▁implemented ▁by ▁the ▁super comput er ▁vend ors ▁C ray ▁Computer ▁Corporation , ▁Con vex , ▁and ▁Al li ant ▁in ▁an ▁attempt ▁to ▁stay ▁ahead ▁of ▁the ▁ever -