Long carrier lifetime in ultrahigh-density InAs quantum-dot sheet of intermediate band solar cells

In-plane ultrahigh-density InAs quantum dots with 3 - 5 × 10
¹¹
cm
^-2
were grown on the GaAsSb/GaAs(001) by MBE. PL properties of the ultrahigh density QDs with small size revealed lateral coupling of electrons in the in-plane QD sheet. Long PL decay time of 4-6 ns was observed for laterally coupled QD sheet, spite of type-1 band alignment. The PL decay time drastically decreased under high electric field. It was explained by change of the electronic states and electron escape. For forward bias voltage, long PL decay time of 10 ns was observed.