Designed active region structure, conduction band profile, squared envelope functions, and carrier densities. a The layer sequence for one period is 1.6/6.2/1.6/3.4/1.0/3.4 nm. Barriers are indicated in italics font. The 6.2 nm-thick well is n-doped with n = 5 × 1017 cm−3. b Conduction band profile and squared envelope functions of the GaN/Al0.15Ga0.85N QCL considered in this study. An electric field of − 84.5 kV/cm is applied. c Carrier densities and conduction band of the QCL calculated in the NEGF model. The electric field applied is − 84.5 kV/cm. Temperature is set at 10 K.