Impact of optical absorption for THz radiation in GaSb/InAs heterostructures

Terahertz radiation characteristics were systematically investigated for InAs/GaSb/InAs heterostructures by varying the thickness of the GaSb hot-electron injection layer between 5 and 50 nm. Monotonic increase in the radiation intensity was observed as the GaSb injection layer thickness was reduced. Enhanced radiation compared to InAs film without the GaSb injection layer occurred only for the GaSb layer thickness of 5 nm. We also studied the impact on the radiation intensity by introducing an In 0.2 Ga 0.8 Sb injection layer, and found that intensified radiation occurred even for the layer thickness of 20 nm implying the effect of increased optical absorption in the InGaSb injection layer.