Evidence of carrier localization in photoluminescence spectroscopy studies of mid-wavelength infrared InAs/InAs1−xSbx type-II superlattices

摘要: Abstract The temperature-dependent and excitation-dependent photoluminescence (PL) spectroscopy characterization of mid-wavelength infrared InAs/InAs1−xSbx type-II superlattices reveals evidence carrier localization. Carrier localization is apparent in the 8 meV PL peak position blue shift from 4 K to 60 K while full-width-at-half-maximum non-monotonic, peaking at 25 K before increasing above 60 K. In addition, competition between two recombination processes evident behavior integrated intensity under low excitation conditions: decreases 80 K, increases 80 K 160 K, 160 K. Excitation-dependent studies reveal dominant mechanism changes free-to-bound or donor–acceptor-like excitonic band-to-band ~60 K. These findings suggest that occurring below 60 K, confined carriers are holes as these unintentionally doped n-type superlattices. potentials due variations InAs1−xSbx composition, interfaces, InAs layer widths. width a Gaussian distribution used describe density states band tails ranges 2 meV–4 meV. larger energy corresponds smaller period superlattices, indicating interface compositional variation more prominent creates than longer