A detailed investigation on the impact of post-growth annealing on the materials and device characteristics of 35-layer In0.50Ga0.50As/GaAs quantum dot infrared photodetector with quaternary In0.21Al0.21Ga0.58As capping

The effect of post-growth rapid thermal annealing on 35-layer In0.50Ga0.50As/GaAs quantum dot infrared photodetector (QDIP) with quaternary In0.21Al0.21Ga0.58As capping has been investigated. Transmission electron microscopy showed some as-grown defects were removed by post growth annealing treatment. An increase in the compressive strain in the heterostructure due to annealing was identified from X-ray diffraction curve. A two-color photoresponse in the long-wave region (8.5 and 10.2 μm) was observed in both as-grown device and those annealed at 650 °C temperature. A three-fold enhancement in peak responsivity was observed in the QDIPs annealed at 650 °C (1.19 A/W) compared to that in the as-grown (0.34 A/W). Detectivity also increased by two fold from as-grown to 650 °C annealed device. The changes are attributed to the removal of as-grown defects and dislocations during epitaxial growth. These removals changed the confinement potential profile, which resulted in an improvement in the detectivity and responsivity of the annealed sample.

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► We investigated the effect of ex situ annealing on InGaAs/GaAs QDIP with InAlGaAs layer.
► As-grown defect was removed by using post-growth annealing treatment.
► Increase in the compressive strain due to annealing is calculated from XRD curve.
► Three-fold enhancement in responsivity is observed in the QDIPs annealed at 650 °C.
► Two-fold enhancement in D* is observed sample annealed at 650 °C compared to as grown.