Impact of alloyed capping layers on the performance of InAs quantum dot solar cells

摘要: Abstract The impact of using thin GaAs(Sb)(N) capping layers (CLs) on InAs/GaAs quantum dots (QDs) is investigated for their application in solar cell devices. We demonstrate the ability to combine strain-balancing techniques with band engineering approaches through such CLs. Extended photoresponse attainable by means an independent tunability electron and hole confinements QD. Moreover, CL acts itself as a well (QW), providing additional photoresponse, so that devices work hybrid QD–QW cells. use GaAsSb particularly beneficial, efficiencies under AM1.5 conditions 20% higher than standard GaAs-capped QDs. This mainly due significant increase photocurrent beyond GaAs bandgap, leading enhanced short-circuit current density ( J sc ). addition N CLs, however, produces strong reduction . found be related carrier collection problems, namely, hindered extraction retrapping Nevertheless, reverse biases induces release trapped carriers assisted sequential tunneling mechanism. In case GaAsN this leads complete reveals even QD–QW-related when CL. stronger quaternary likely faster recombination rates type-I GaAsSbN/GaAs QW structure compared type-II ternary counterparts. alternative approaches, thinner or short-period superlattice CL, lead improvements, demonstrating great potential CLs proper device design.