From Localised to Ballistic Excitons in GaAs Quantum Wells

Abstract

A CT A P HY SIC A P O LO N IC A ANo . 3 P r oceedi n gs of t h e XXX I n t ern at io n al Sch oo l o f Sem icond uct i ng Co m p ou n ds, Ja szo wi ec 200 1Fr om L ocali sed to B allis tic E x cito n s in G aAs Q u antu m W ells T h e lateral mot ion of exciton s in Ga A s quantum w ells is stu died by means of spatial ly resol ved photolumi nescence. W e show that at low temp eratures (4. 2 K ) the exciton motion evolves from localised excitons ( zero mobili ty) in thin quantum w ells to extremely hi gh mobili ties in w ide w ells.W e Ùnd that for the w idest quantum well investigated the observed motion cannot be explai ned by simple exciton di˜usi on and must b e explai ned by the propagation of balli sti c exciton p olaritons . PAC S numb ers: 71.35.{y , 71. 36.+ c