This work shows the importance of interface consideration at the barrier sides for quantum well (QW)-based semiconductor structures, on the example of the InAs/AlSb heterostructure. Various interface combinations of AlAs and InSb type have been included in an LnAs/AlSb double-barrier resonant-tunneling-diode structure, and the resulting transmission functions have been calculated. A systematic comparison of the resulting structures with each other and also with the traditional case without interface consideration have been made. Clear tendencies and relationships observed in the transmission characteristics of the different structures let the interface tuning emerge as a quality tool for QW-device tayloring.