Heterogeneously coupled InAs Stranski-Krastanov and submonolayer quantum dot infrared photodetector for next-generation IR imaging

摘要

In the present work we are introducing heterogeneously coupled InAs stranski-krastanov and submonolayer quantum dot as an active material for quantum dot based infrared photodetector. Initially, we have optimized the basic SK on SML heterostructure. The thickness of the GaAs barrier layer is varied from 2.5 to 7.5 nm to tune the vertical coupling between seed SML and top SK QDs. PL and PLE response confirms the carrier tunneling between these heterogeneous QDs. The vertical alignment of SML and SK QDs is shown in Cross sectional TEM images. The sample with 7.5 nm barrier layer is incorporated into a N-I-N based quantum dot infrared photodetector, which shows broader spectral response than standard SK QD based IR detectors.