Minority Carrier Lifetimes in InSb/InAsSb Quantum Dot and InAsSb nBn Photodetectors

The energy level scheme and the minority carrier lifetime in a type-II midwave InSb/InAs
_0.92
Sb
_0.08
quantum dot structure were compared with bulk InAs
_0.915
Sb
_0.085
using photoluminescence, absorption, and optical modulation response. Two hole energy levels separated by ~65 meV were identified in the quantum dots, and a decrease of the hole energy barrier with increasing temperatures was observed. The quantum dot minority carrier lifetime increased from 700 ns at 77 K to 1230 ns at 175 K, and is significantly longer than the bulk InAs
_0.915
Sb
_0.085
lifetime of 300 ns. By insertion of quantum dots in the bulk material, the dominating recombination mechanism changed from the Shockley-Read-Hall to radiative recombination.