High internal quantum efficiency in AlGaN multiple quantum wells grown on bulk AlN substrates Available to Purchase

The internal quantum efficiency (IQE) of Al_0.55Ga_0.45N/AlN and Al_0.55Ga_0.45N/Al_0.85Ga_0.15N UVC MQW structures was analyzed. The use of bulk AlN substrates enabled us to undoubtedly distinguish the effect of growth conditions, such as V/III ratio, on the optical quality of AlGaN based MQWs from the influence of dislocations. At a high V/III ratio, a record high IQE of ∼80% at a carrier density of 10¹⁸cm⁻³ was achieved at ∼258 nm. The high IQE was correlated with the decrease of the non-radiative coefficient $A$ and a reduction of midgap defect luminescence, all suggesting that, in addition to dislocations, point defects are another major factor that strongly influences optical quality of AlGaN MQW structures.